The first I
heard of this disease was when I took a Babe into my vet for a health check
just a couple days after I got her. I had been waiting for her for a
long time and she had been ill prior to my getting her. Even though I
was told she had been tested heart worm negative I had my vet recheck her
just for my piece of mind. She had come from an area in the country
with very little heart worms and had not even been tested for it until I
asked about it. This time my paranoia paid off because in addition to
testing for heart worms my vet also tested for C.E. And she was absolutely,
no doubt about it, positive!
We had spent
quite a while talking and working with Babe before this test was done.
There had been so many things which had not been thought out well before I
got her and she had been treated incorrectly for months with a variety of
drugs. Treating the symptoms of the problem instead of considering
that they were symptoms of a bigger problem. I understand that this is
the single most common problem with healing with C.E. There is a
tendency to not put the problems together in one package, all caused by one
is carried by the brown dog tick and is more common in areas with a larger
tick population/infestation. Keeping and maintaining tick free kennels
will help but doesn't assure an animal will not be infected, but it
helps. There are 2 phases of the disease, acute and chronic. The
acute variety usually shows within the first 3 weeks or so of being
bitten. Some symptoms are fever, runny eyes/nose, swollen lymph nodes
among others. This variety responds well to treatment in a short
amount of time...usually going into remission and a return to health.
however usually can wait several months before signs start to show.
Prolonged high temp, dehydration, no appetite, inability to keep food down,
weight loss and lots of others as well. This phase of the disease, with
proper medication, may have a good life. Both varieties require
antibiotics in the form of tetracycline. Up until recently this has been the
only drug available in the US for treatment but just recently another one
which has been used abroad has come here...I am unclear at this point if it
is simply for research or wither we can actually get it for our babies. I
will keep you all posted as L learn more about that aspect. Unfortunately
the chronic form of the disease can kill.
disease affects the immune system you really need to be careful about
booster vaccinations. I have had to make the decision to not give her
a 6 month Parvo booster at this time until she is stronger and we can learn
more about what the consequences might be. Right now my little Babette has
good days and bad days. She gets her medication 3 times a day and is
also taking antibiotics in an olive oil based eye drops in both eyes for
ulcers she has on both corneas... We have 2 weeks to go on that and
then will go in for testing.
is out there. It has been reported in every state and worldwide as
well. You cannot get it from an infected dog but you can from an
infected tick. If you have a dog with the problem, would like to share
your story or have more links I would be delighted to have the info to add
An Overview of Canine
Lauren Bockino, B.S.;
Paula M. Krimer, DVM, DVSc; Kenneth S. Latimer, DVM, PhD; and Perry J.
Bain, DVM, PhD
Class of 2003, Ross
University, School of Veterinary Medicine, St. Kitts, West Indies (Bockino)
and Department of Pathology (Krimer, Latimer, Bain), College of
Veterinary Medicine, University of Georgia, Athens, GA 30602-7388
The Ehrlichiae are a
group of small, gram-negative, pleiomorphic, obligate intracellular cocci
that infect different blood cells in various animal species and in
humans. There has recently been a reclassification of the family Anaplasmataceae
to which the Ehrlichiae belong.8 According to this new
classification there are two leukotrophic diseases in dogs that are
caused by bacteria in the genus Ehrlichia, namely, Canine Monocytic
Ehrlichiosis (caused mainly by Ehrlichia canis) and Canine
Granulocytic Ehrlichiosis (caused by Ehrlichia ewingii). It should
be noted that cross-reactivity and co-infection is common among the
ehrlichiae.7 Classically, canine ehrlichiosis presents as a
rather non-specific multisystemic disorder with the primary complaints
being depression, lethargy, mild weight loss, vomiting, diarrhea, and
anorexia, with or without hemorrhagic tendencies. Furthermore, patients
may present with uveitis and/or retinal petechiae, polymyositis,
polyarthritis, and central nervous system signs.2 Hematologic
abnormalities most commonly associated with canine ehrlichiosis include
nonregenerative anemia and thrombocytopenia. Serum chemistry commonly
reveals hyperglobulinemia (monoclonal or polyclonal gammopathy),
hypoalbuminemia, and low albumin-globulin ratio.5
Monocytic Ehrlichiosis (Ehrlichia canis)
Canine Monocytic Ehrlichiosis
(CME), caused by E. canis, is an acute to chronic disease of
monocytes, and is the ehrlichial disease most extensively studied. This
organism is primarily transmitted by Rhipicephalus sanguineus, the
brown dog tick. It is seen mostly in the southeastern and southwestern
United States, although it is recognized in all states and worldwide. Amblyomma
and Dermacentor ticks have also been implicated in transmission of
this disease.3 Dogs may present with variable clinical signs,
but thrombocytopenia with bleeding tendencies is the most consistent
presenting complaint in dogs in both the acute and chronic stages of the
disease.1 During the acute stage, splenomegaly and
lymphadenomegaly are common. In the chronic stage, widespread hemorrhage
and increased mononuclear cell infiltration of organs may also be
evident. Hematologic changes include nonregenerative anemia,
thrombocytopenia, and leukopenia. Pancytopenia may occur as a result of
hypoplasia of all bone marrow precursor cells, more commonly in the
severe chronic phase.4 Some dogs may develop a secondary
immune-mediated hemolytic anemia (IMHA) and have an acute hemolytic
crisis, and, thus, a positive direct antiglobulin (Coombs') test.1
Granulocytic Ehrlichiosis (Ehrlichia ewingii)
Ehrlichiosis (CGE) caused by Ehrlichia ewingii, is a disease of
neutrophils and, rarely, eosinophils. CGE classically presents with mild
signs including fever, lethargy, anorexia, weight loss, vomiting,
diarrhea, severe but transient thrombocytopenia, and transient mild
nonregenerative anemia with ineffective erythropoeisis. Commonly, the
major presenting clinical signs associated with E. ewingii include
lameness and joint swelling due to polyarthritis. This form of
ehrlichiosis is generally seen in the southern and mideastern United
States.1,4 Ticks including Ixodes pacificus, Dermacentor
variabilis, Rhipicephalus sanguineus, Amblyomma americanum (especially
in North Carolina), and Ixodes scapularis (damminni) have
been implicated as vectors.3,6
The pathogenesis of
infection with E. canis is the most extensively studied; therefore
this discussion will focus on this particular species.
Infection occurs through
salivary secretions of the tick at the attachment site during ingestion
of a blood meal or through blood transfusions. If the adult Rhipicephalus
sanguineus engorges on the dog during the acute stage, it can
transmit the disease to other dogs for at least 155 days following
detachment.1 Transmission by Rhipicephalus sanguineus is
transstadial: the tick acquires the bacteria by feeding on an infected
dog in either the larvae or nymph form and the tick transmits the disease
to another dog as either the nymph or adult form. The life cycle of
Ehrlichia is not yet completely understood but it is thought that it
occurs in three intracellular forms. The initial bodies are small
spherical structures (1-2 micrometers in diameter) which are believed to
develop into larger multiple membrane-bound units known as morulae. The
morulae are inclusions within the cytoplasm of the leukocyte as seen in
Figure 1. This morula is thought to then dissociate into small granules
called elementary bodies.
canis seen in a membrane-bound inclusions (morulae) within
the cytoplasm of a monocyte (buffy coat smear, Wright stain).
After an incubation
period of 8-20 days, the acute phase of infection occurs which lasts 2-4
weeks. At this time, the organism multiplies within circulating
mononuclear cells and the mononuclear phagocytes within the liver,
spleen, and lymph nodes. The infected cells are then transported in
circulation to the rest of the body, with a predilection for the
lungs, kidneys and meninges. Cells infected with ehrlichia adhere to the
vascular endothelium and induce a vasculitis and subendothelial tissue
infection. This subsequently leads to platelet consumption,
sequestration, and destruction that results in the thrombocytopenia seen
during this acute phase. Variable leukocyte counts and anemia may also
develop progressively during this stage.1 After 6-9 weeks,
dogs will either eliminate the parasite (if immunocompetent) or develop a
parasitemia in which clinical signs absent to mild to severe. This stage
is also characterized by variable persistence of thrombocytopenia,
leukopenia, and anemia. Dogs that cannot mount an effective immune
response will become chronically infected.1
Definitive diagnosis of
CME requires visualization of morula within monocytes on cytology,
detection of E. canis serum antibodies with the indirect
immunofluorescence antibody test (IFA), polymerase chain reaction (PCR)
amplification, and/or gel blotting (Western immunoblotting).
On cytology, ehrlichiae
stain dark blue to purple with Romanowsky stain. The morulae are
well-defined, round to oval, eosinophilic to basophilic bodies found in
host membrane-lined vacuoles within the cytoplasm of the mononuclear
In dogs experimentally
infected with E. canis, the IFA test has detected serum antibodies
as early as 7 days after initial infection, although some dogs do not
become seropositive until 28 days post-infection. If ehrlichiosis is
highly suspected clinically in a seronegative dog, serology should be
repeated in 2-3 weeks. In the past, titers of IgG antibodies of >1:80
have been considered diagnostic,1 but the most recent research
has indicated that titers <1:80 should be deemed suspect and serology
should be repeated in 2-3 weeks or a PCR or Western immunoblotting should
be considered. A diagnosis should be made and treatment instituted when
clinical signs and clinicopathological abnormalities consistent with
canine ehrlichiosis are found.2
There are a few
potential downfalls of using the IFA test for the diagnosis of E.
canis infection. One major concern exists in endemic areas with dogs
that are chronically infected and have a positive titer, but are
otherwise healthy or show non-specific clinical signs. In these dogs, a
positive antibody titer does indicate past exposure to E. canis,
does not prove that ehrlichiosis is necessarily an active infection or
the cause of the presenting clinical signs. In dogs with non-specific
clinical signs, a repeat IFA test after 1 or 2 weeks may be beneficial to
differentiate between primary E. canis infection and another
secondary disease. Antibody titers to E. canis should increase
with active infection. Furthermore, one must consider co-infection with
multiple tick-borne diseases caused by agents such as other Ehrlichiae, Rickettsia species,
Bartonella species, and Babesia
canis. Disease caused by any of these agents may be clinically,
hematologically, and serologically indistinguishable from each other. In
addition, the immunodominant proteins of E. canis have been shown
to serologically cross-react with those of E. chaffeensis (the
agent that causes Human Monocytic Ehrlichiosis). Studies have shown that
serologic testing by IFA could not consistently distinguish between
infections of these two species. Interpretation of E. canis
serology should include the consideration of the disease process, cross-reactivities
with other ehrlichial species, the possibility of multiple tick-borne
infections, and persistent IFA antibody titers post-treatment. Antibody
titers be used to gauge the success or failure of treatment of CME.
Treatment success should be based on remission of clinical signs, a
decline in E. canis antibody titers and a concurrent decrease in
PCR amplification is
also a sensitive method for the detection of acute E. canis
although there are currently several potential limitations. It is
recommended that this method be used in addition to serology for the
initial diagnosis of ehrlichiosis, not instead of it.2
The diagnosis of CGE
differs from that of CME as E. ewingii has not yet been cultivated
in an in vitro system, therefore antigens have not been available
for comparative serological testing. Diagnosis of CGE requires
visualization of morula within neutrophils in peripheral blood (Figure
2), joint effusions, and PCR or Western immunoblot.3 In a
study using Western immunoblots, sera from dogs that were experimentally
infected with E. ewingii were tested on E. canis antigens.
Although there were no reactions with the dominant E. canis
antigens, the sera produced binding patterns similar to those of anti-E.
canis sera with high molecular proteins. This also may help with the
diagnosis of CGE.7
segmented neutrophil from a dog that contains morula of a
granulocytic species of Ehrlichia, most commonly Ehrlichia
ewingii (blood smear, Wright stain).
The mainstay of
prevention of canine ehrlichiosis is tick control. The drug of choice for
treatment for all forms of ehrlichiosis is doxycycline for at least one
month. There should be dramatic clinical improvement within 24-48 hours
following initiation of treatment in dogs with acute-phase or mild
chronic-phase disease. During this time, platelet counts begin to
increase and should be normal within 14 days after initiation of
treatment.1,2 Polyarthritis associated with E. ewingii
may be self-limiting.3 Previous infection does not confer
lifelong immunity, and dogs can become reinfected with the same or other
ehrlichial species after re-exposure to infective ticks.
1. Ettinger SJ, Feldman
EC: Textbook of Veterinary Internal Medicine: Diseases of the Dog and
Cat, vol. 1, 5th ed. W.B. Saunders Co., Philadelphia,
2000, pp. 402-406.
2. Neer TM,
Breitschwerdt EB, Greene RT, Lappin, MR: Consensus statement on
ehrlichial disease of small animals from the Infectious Disease Study
Group of the ACVIM. J Vet Intern Med 16:309-315, 2002.
3. Goldman EE,
Breitschwerdt EB, Grindem CB, Hegarty BC, Walls JJ, Dumler JS:
Granulocytic ehrlichiosis in dogs from North Carolina and Virginia. J
Vet Intern Med 12:61-70, 1998.
4. Neer TM: Canine
monocytic and granulocytic ehrlichiosis. In: Greene CE (ed): Infectious
Diseases of the Dog and Cat, 2nd ed. W.B. Saunders Co.,
Philadelphia, 1998, pp.139-147.
5. Varela F, Font X,
Valladares JE, Alberola J: Thrombocytopenia and light-chain proteinuria
in a dog naturally infected with Ehrlichia canis. J Vet Intern
Med 11:309-311, 1997.
6. Wolf L, McPherson T,
Harrison B, Engber B, Anderson A, Whitt P: Prevalence of Ehrlichia
ewingii in Amblyomma americanum in North Carolina. J Clin
Microbiol 38:2795, 2000.
7. Waner T, Harrus S,
Jongejan F, Bark H, Keysary A, Cornelissen A: Significance of serological
testing for ehrlichial diseases in dogs with special emphasis on the
diagnosis of canine monocytic ehrlichiosis caused by Ehrlichia canis.
Vet Parasitol 95:1-15, 2001.
Research Laboratory, College of Veterinary Medicine, The Ohio State
University, Columbus, OH
"Barbara's Dogs" by Tom Martin, New
Moon Illuminations, is used with permission of the artist.
Clinical Name: Ehrlichiosis, Ehrlichia
Dogs get ehrlichiosis from the brown dog tick,
which passes an Ehrlichia organism into the bloodstream when it
bites. There are three stages of ehrlichiosis, each varying in severity. The
acute stage, occurring several weeks after infection and lasting for up to a
month, can lead to fever and disorders of the blood. The second stage,
called the sub clinical phase, has no outward signs and can last for up to
five years. If the infected dog’s immune system is unable to eliminate the
Ehrlichia organism, the third and most serious stage of infection,
the chronic phase, will commence. Lameness, neurological and ophthalmic
disorders, kidney disease, and anemia and other blood disorders can result.
Chronic ehrlichiosis can be fatal.
Antibiotics, administered for an
extended period of time, are effective at eliminating the infection. Dogs
with severe cases of chronic ehrlichiosis cannot be cured, but supportive
care and treatment of diseases secondary to the infection, such as anemia,
can help stabilize the dog.
Clinical Signs and Symptoms
The acute stage of the disease, occurring most
often in the spring and summer, begins one to three weeks after infection
and lasts for two to four weeks. Clinical signs include a fever, petechiae,
bleeding disorders, and vasculitis. There are no outward signs of the
sub clinical phase, which can last for up to five years. Clinical signs of
the chronic phase include pale gums due to anemia, thrombocytopenia,
vasculitis, lymphadenopathy, respiratory dyspnea, coughing, polyuria,
polydipsia, lameness, ophthalmic diseases such as retinal hemorrhage and
anterior uveitis, and neurological disease.
Diagnosis is achieved most commonly by serologic
testing of the blood for the presence of antibodies against the Ehrlichia
organism. During the acute phase of infection, however, the test can be
falsely negative because the body will not have had time to make antibodies
to the infection. Thus, the test will need to be repeated if the first
result is negative. In addition, blood tests will show abnormalities in the
numbers of red cells, white cells, and platelets. Uncommonly, a diagnosis
can be made by looking under a microscope at a blood smear for the presence
of the Ehrlichia organism, which sometimes can be seen within a white
Ehrlichiosis is a tick-borne disease of dogs that
is caused by an organism called Ehrlichia. There are several species
of Ehrlichia, but the one that most commonly affects dogs and causes
the most severe clinical signs is Ehrlichia canis. The brown dog
tick, or Rhipicephalus sanguineous, that passes the Ehrlichia
to the dog is prevalent throughout most of the United States, but most cases
tend to occur in the Southwest and Gulf Coast regions where there is a high
concentration of the tick.
There are three stages of the Ehrlichia canis
infection: acute, sub clinical, and chronic. Approximately one to three weeks
following the infection, clinical signs of the acute phase begin and
typically last for two to four weeks. The sub clinical phase, which does not
produce outward clinical signs, lasts for up to five years. If the dog’s
immune system is unable to eliminate the organism during this stage, the
chronic phase will occur and may last for years, depending on the severity
of the infection. Dogs that are severely affected can die from this disease.
Although people can get ehrlichiosis, dogs do not
transmit the bacteria to humans; rather, ticks pass on the Ehrlichia
organism. Clinical signs of human ehrlichiosis include fever, headache, eye
pain, and gastrointestinal upset.
Transmission or Cause
The Ehrlichia organism is passed to the dog
through the saliva of a tick called Rhipicephalus sanguineous. These
ticks are prevalent throughout most of the United States, but most cases of
infection tend to occur in the Southwest and Gulf Coast regions.
Supportive care must be provided to animals that
have clinical signs. Subcutaneous or intravenous fluids are given to
dehydrated animals, and severely anemic dogs may require a blood
transfusion. Treatment for ehrlichiosis involves the use of antibiotics such
as doxycycline for a period of at least six to eight weeks; response to the
drugs may take one month. In addition, steroids may be indicated in severe
cases in which the level of platelets is so low that the condition is life
The prognosis is good for dogs with acute
ehrlichiosis. For dogs that have reached the chronic stage of the disease,
the prognosis is guarded. When bone marrow suppression occurs and there are
low levels of blood cells, the animal may not respond to treatment.
Prevent tick infestation by avoiding tick-infested
areas. In addition, there are many methods for controlling fleas, including
medicated shampoos, dips, sprays, the Preventic® collar, or Frontline®. If
tick control is not feasible, tetracycline at a lower dose can be given
daily for 200 days during the tick season in endemic regions.
republished here with permission from VetCentric.com
Copyright(c) 2000 by VetCentric.com
Drs. Foster & Smith, Inc.
Veterinary Services Department
Canine ehrlichiosis is a disease of dogs and wild
canids (e.g., wolves) and is found worldwide. Canine ehrlichiosis is also
known by other names such as "tracker dog disease", "tropical
canine pancytopenia", "canine hemorrhagic fever", and
"canine typhus". It affected a large number of military dogs in
the war in Vietnam.
Ehrlichiosis can be caused by several organisms
including Ehrlichia canis, E. equip, E. platys, E.
ewingii, and possibly others. The Ehrlichia organisms are what we
call rickettsia which on the evolutionary scale are between bacteria and
How is Ehrlichia transmitted?
transmitted by the brown dog tick, Rhipicephalus sanguineus. The
immature form of the tick feeds on an animal infected with Ehrlichia.
When these immature forms or a mature form of the tick feeds on another
animal, the Ehrlichia is passed on to that animal. The Ehrlichia
can remain alive in the developing tick for up to 5 months. This means a
tick could become infected in the fall, and infect a dog the following
Because the disease is transmitted by the brown dog
tick, it can occur wherever brown dog ticks are found. Almost every state in
the United States has reported a case of ehrlichiosis.
What are the symptoms of
Ehrlichiosis can have three phases. Signs of the
phase of the disease usually develop 1-3 weeks after the bite of the
infected tick. The acute phase of the disease generally lasts 2-4 weeks. The
Ehrlichia enter certain cells of the body and reproduce inside of
them. These cells are found in the lymph nodes, spleen, liver,
blood, and bone marrow. As a result of the infection the lymph nodes, liver
and spleen are often enlarged. Anemia,
fever, depression, lethargy, loss of appetite, shortness of breath, joint
pain and stiffness, and bruises are often seen.
In the sub clinical phase the animal may show only
slight anemia. During this phase the dog either eliminates the Ehrlichia
from the body or the infection may progress to the chronic
The chronic phase generally develops 1-4 months
after the tick bite and can be either mild or severe. Weight loss, anemia,
neurological signs, bleeding, inflammation
of the eye, edema (fluid accumulation) in the hind legs and fever may be
seen. Blood tests show that one or all of the different blood cell types are
decreased. One cell type, the lymphocyte may increase and be abnormal in
appearance. This can sometimes be confused with certain types of leukemia.
If a dog becomes chronically infected, the disease can keep coming back,
especially during periods of stress.
A decrease in the number of platelets (platelets
help the blood clot) in the blood is the most common laboratory finding in
all phases of the disease. Changes in the protein levels in the blood are
common. The most common protein, albumin, is decreased and other types of
protein called "globulins" are increased.
Since one tick could be infected with and transmit
more than one disease (e.g., haemobartonellosis
it is not all that uncommon to see a dog infected with more than one of
these diseases at a time which generally causes more severe symptoms.
How is ehrlichiosis diagnosed?
A highly accurate blood test which tests for the
dog's antibodies (proteins produced to fight off the infection) to Ehrlichia
is available. It is called the indirect immunofluorescent antibody (IFA)
test. The antibodies may not be detected in the early phase of the disease
since it takes some time for the body to make them. As the disease
progresses, the antibody level will rise significantly. Often two tests will
be done 2 weeks apart and the results compared. Dogs with an active
infection will show a significant rise in the amount of antibody present.
A newer test called the ELISA test is becoming more
available and the test can be run in your veterinarian's laboratory. This
test also determines the amount of antibodies present.
The antibodies can last for one or more years after
the infection, but they do not make the dog immune to ehrlichiosis - the dog
could get reinfected.
Sometimes the organism can be seen inside cells on
a blood smear. To find them, a small drop of blood is spread over a
microscope slide, stained and examined under the microscope. The organism
can only be found in the blood stream for about 3 days during the acute
phase of the disease. So this method of diagnosis could miss some cases of
How is ehrlichiosis treated?
The antibiotics tetracycline or doxycycline are
used. Treatment is for 2-3 weeks. Some dogs will need blood transfusions or
fluids depending on the severity of the disease. Generally the prognosis
during the acute phase is good if the animal is properly treated. Dogs who
go on to the chronic phase have a poorer prognosis. German shepherds and
Doberman pinschers tend to have a more severe chronic form of the disease.
The drug imidocarb dipropionate is sometimes used
in conjunction with the antibiotics. It is given as an injection, but may
not be available in all areas.
Some of the damage caused by Ehrlichia may
be due to the dog's own immune response to the organism. For this reason,
high doses of corticosteroids
(e.g., prednisolone) are often given during the early phase of the disease.
How can I prevent ehrlichiosis in my pet?
Tick control is the main way to prevent
ehrlichiosis. Products which repel and kill ticks such as Biospot for Dogs
are excellent choices. Tick collars containing the active ingredient amitraz
(Preventic collars) are also used, sometimes in conjunction with Biospot in
those areas with high tick infestations.
If a large number of cases of ehrlichiosis are diagnosed in an area, some
veterinarians recommend placing dogs on low doses of tetracycline or
doxycycline during the tick season.
There is no vaccine for
Can people get
Yes. The common symptoms in people include fever,
chills, headache, and muscle aches. Other less common symptoms include
nausea, loss of appetite, weight loss, abdominal pain, cough, diarrhea and
change in mental status.
People do NOT get infected directly from a dog, but
through a tick bite. Human ehrlichiosis may be spread by a different tick
than the brown dog tick. Research suggests the Lone Star tick may be
involved. Also, the Ehrlichia species most often implicated in human
infections is E. chaffeensis.
Couto, DG. Rickettsial Diseases. In Birchard, SJ;
Sherding, RG (eds): Saunders Manual of Small Animal Practice. WB Saunders
Co., Philadelphia PA; 1994;124-5..
Harrus, S; Bark, H; Waner, T. Canine monocytic
ehrlichiosis: An update. Compendium of Continuing Education for the
Veterinary Practitioner 1997;19 (4) :431-444.
Olson, JG. Ehrlichiosis. In: Zoonoses updates from
the Journal of the American Veterinary Medical Association. American
Veterinary Medical Association, Schaumburg IL; 1995:74-75.
Ibulaimu Kakoma DVM PhD
First I want to thank Jan and Bob for giving me the
opportunity to make some remarks and to congratulate them for undertaking
such heavy and well executed responsibility to address this important issue.
Their basic premise was to reach the owner/breeder and also to establish
dialogue with the veterinary clinicians and scientists outside the vet's
office. I think they have achieved both. The owners and breeders will gather
tremendous information from this article in a language they will understand
since there is a minimum of technical jargon to cloud their reading
enthusiasm. The veterinarian and scientist will get the challenging message
that the 21st century clients have modern tools to watch everything we do
and publish and they are looking for a practical product for their pet....
at times regardless of how much it will cost. The clients are also prepared
to work with us to the extent possible and when they question our training
they are not vet bashing but trying to develop a dialogue.
The authors are right in indicating that diseases
have no borders. Today the definition of a tropical disease could not have
been more nebulous and blurred! That is why we have task forces in USA and
Europe to deal with "Emerging diseases" which show up suddenly and
unexpectedly. In some ways ehrlichiosis meets that definition.
This raises the issue of training in tropical
medicine. The authors' point is well taken that veterinary curricula are
facing the challenge to accommodate the problems of newly emerging diseases,
such as ehrlichiosis.
Extra attention needs to be paid to this segment if
future veterinarians are going to be prepared for diseases that just emerge
here or encountered in missions overseas. It is gratifying to know that
there is a Society of Tropical Veterinary Medicine and "Intervet"
which expose our veterinary community to so- called foreign diseases. The
USDA at Plum Island along with the CDC are examples of establishments that
have enormous resources to educate all of us on these issues.
Bob and Jan bring up the issue of the complexity of
ehrlichiosis. In fact the disease is more of a syndrome. Readers will
appreciate this from articles such as that written by David Huxsoll who has
so neatly categorized the stages of the disease. The spectrum of syndromes
and disease entities imitated by ehrlichiosis are incredible, emphasizing
the need to carefully rule out ehrlichiosis for common infectious diseases.
The warning signs may certainly be subtle. Can one
rule out ehrlichiosis by the IFA test and should we treat all animals which
are IFA positive? First, a positive IFA test simply means "current or
previous exposure" ........treatment or recovery does not guarantee a
Any patient positive in the IFA and presenting with
signs consistent with ehrlichiosis should definitely be treated. Indeed
empirical treatment is reasonable if in the clinician's assessment waiting
for the IFA results could endanger the patient. IFA could certainly be
negative during the very early phase of the disease even when severe signs
Therefore, in the writer's opinion a clinical
assessment may supercede the IFA status. A positive IFA test excludes a dog
from being a blood donor and membership of a breeding stock for the fear of
transmitting the disease and every effort should be made to research into
methods of terminating the carrier state.
Provided the treatment is prescribed and monitored
by a veterinarian, it seems less risky to treat IFA positive animals
resident in a non-endemic area than to risk a severe disease. In an endemic
area, however, treatment on the basis of the IFA test per se cannot be
justified since the patient will again be exposed and the synergistic
advantage between antibodies and the cellular immune system may be of value
in fighting the new infection. In other words, in areas where the diseases
are common practically every dog has been exposed and treatment can only be
justified on the basis of the clinical disease.
The relatively low endemicity in many parts of
North America means that supervised treatment of early diagnosed( by IFA or
PCR) cases is worthwhile to prevent costly potential worsening of the
patient's condition or even death, as mentioned by Bob and Jan. They have
shared with us their private experiences in which intervention helped some
cases and when the problem was recognized too late the patient could not be
saved. It must be emphasized, however that empirical treatment with
antibiotics must be carefully evaluated and monitored to avoid abuse of
these important compounds.
The other issue raised is "early
diagnosis". The PCR test is showing promise and perhaps in future it
will be available routinely. Because the test is DNA-based, it offers the
most specific and sensitive detection method which confirms that the patient
is definitely infected and treatment would be indicated without any doubt.
Finally, we must join the authors in a crusade to find alternative drugs to
doxcyline and tetracyline in case we encounter resistance to these drugs or
we are treating mixed infections ( e.g. ehrlichiosis and babesiosis). A case
in point is Imizol® a well tested drug used in may parts of the world but
not legally available for dog treatment in USA. (Since the article was
written in 1996 , unfortunately, little has changed. However, one important
change is the fact that Imizol is now available and your vet should be able
to easily obtain it. This drug is given by injection in a series, normally,
of two shots two weeks apart. - Bob Wilson 1/14/2000). Compassionate
users of Imizol® have reported impressive results in cats and dogs
suffering from ehrlichiosis and we should continue research to facilitate
approval by the FDA. The ultimate goal should however be the development of
a vaccine for this disease complex and for that we need to work with the
breeder, the owner, industry and academia. This mission is noble according
to the wishes of friends such as Pajti, Jake, Bear, Saucy and many others
born in the Hendricks and Mair families.
For those searching for additional reading please
search under the following scientists: Ewing, S; Huxsoll, D; Breschwerdt, E;
Dawson, J; Lewis, G E; Holland, C J; Ristic, M R; Dutta; Rikihisa, Y;
Madigan, J; Dumler; Bakken; Nyindo; Roult; Long, M; Goetz; Palmer, G;
Walker, D; and many other scientists.
Ibulaimu Kakoma,DVM PHD
The purpose of this document is to help dog owners as
well as their veterinarians become aware and learn more about a dreaded and
deadly killer that is claiming the lives of dogs in all 50 states.
We also encourage you to reproduce the document
should you wish to pass it on to others. We only ask that it be the complete
document so that nothing is taken out of context and to give credit to those
who labored so diligently in its preparation.
While a lot of detail is contained in this
document, it is thought and hoped that it will be shared with the dog
owners' veterinarian. Many vets are not familiar with ehrlichiosis, do not
appreciate the magnitude of the problem or have treated it as something else
failing to treat the underlying cause. This is in no way meant to condemn
the veterinary community. As you will see, they are reacting to what they
perceive as signs of diseases they are more familiar with, which is a very
logical approach but not one that will work with ehrlichiosis. The nature of
this disease is such that it mimics a great many other diseases, and this
tends to confuse and complicate treatment.
There are many forms of the disease attributed to
the organisms in the genus ehrlichia that are genetically related, including
one of the species recently found in humans which causes the disease HGE
(Human Granulocytic Ehrlichiosis). Another is E. equip
species which causes illness in horses. This is a different species than E.
risticii which causes Potomac Horse Fever and is also found in dogs.
Other identified species are E. sennetsu, human pathogen, E.
ewingii and E. platys, both canine pathogens. The species E.
ewingii has been reported in dogs in Minnesota, and likely occurs in
other states as well.
The two keys to success are early recognition and
Treatment with proper antibiotics can be quite
dramatic in these cases, whereas treating an ehrlichiosis patient with
steroids or drugs other than the tetracycline family will almost certainly
lead to tragedy.
THE TRIP TO THE VET
This section is for the clinician. Please form a
picture in your mind of the following: A client comes into your clinic with
her dog. She is a good client, her dog gets his vaccinations regularly, is
on heartworm preventive, and is obviously well cared for.
But today it is apparent she is very worried about
her pet. You glance at the dog - a middle-aged pleasant animal who looks a
bit tired. "Doctor", the owner begins, "He just isn't himself
lately - he doesn't want to play anymore, and he always enjoyed retrieving
his ball. His coat isn't as nice as usual - he seems to be turning gray
early - he's only 5 years old! We've noticed his breath is really bad, and
sometimes he doesn't want to eat. Then he will eat fine for a few days, but
he will throw up yellow stuff. His eyes are really red too - and sometimes
they have a glassy reflective look like they do at night in a headlight. He
used to love to sleep with us, but now he seems to have trouble getting up
on the bed. And he's always drinking water - I don't remember him ever
drinking so much water. And I've never known him to have so many accidents;
he always used to be so clean - now sometimes he doesn't even ask to go out
- he just goes on the floor like he doesn't care. What could be wrong with
him Doctor? I'm really worried...."
O.K. Doctor, what do you think? Impossible for one
dog to have so many problems? Neurotic owner? Better take a look.....with
the dog up on the table, you take his temp - normal. Eyes are pretty red -
allergies? Coat does look a bit dull, but you've seen worse. You ask about
the food he is eating - how much exercise he is getting - has his routine
Chances are good that this dog may be sent home
with different food, vitamins or a coat additive, advice to cut back on the
evening water so there won't be so many accidents. Maybe he is just bored
and needs more attention. Still, it wouldn't be a bad idea to do a CBC. What
about his difficulty in getting up on the bed - could he be developing
arthritis? Seems kind of young - but maybe he's just getting old before his
time. Then the CBC comes back within normal limits - white count is a little
depressed, but not that bad. He seemed to have a slight cough - could be a
mild case of kennel cough that he just can't shake. Amoxicillin for a couple
of weeks should take care of that.
Sound familiar? This is beginning to happen in
veterinary clinics all over America every day. Because the signs are
run-of-the-mill, it is not the sort of case that even the most detailed
veterinarian is going to get too excited about. We would like to change
that, because there is a very good chance that the dog just described is
suffering from a type of infection often considered as rare - ehrlichiosis.
The fact is, ehrlichiosis is not rare at all, and through this paper, we
hope to dispel that myth - because that myth is resulting in countless
deaths of pet dogs and even cats - and each and every one of these pets was
someone's special friend. It doesn't have to be that way.
Perhaps the most critical thing for the clinician
to remember is to look at the big picture. Does a client's pet really have
several ailments affecting different systems, or could it be suffering from
ehrlichiosis which in essence, affects all systems?
What about the purebred show dog with autoimmune
disease? It is easy to assume this is a genetic problem inherent in the
breed but why not give the dog the benefit of the doubt and consider
ehrlichiosis as a possible cause. Response to treatment with proper
antibiotics can be quite dramatic in these cases, whereas treating an
ehrlichiosis patient with steroids is almost certainly signing its death
Today's veterinarian will also acknowledge that
today's pets travel far and wide with their owners. As a result, the
diseases and vectors are no longer limited to specific regions. Ticks thrive
in cold as well as warm climates and where the tick goes, so goes the
EHRLICHIA - WHAT IS IT?
Surprisingly, Ehrlichia has been around for a lot
longer than most people realize. It was first described in 1935 in Algerian
dogs. However, in 1962 , a number of military dogs (German Shepherds) that
had been stationed in Vietnam died from complications of Hemorrhagic Fever.
It was later determined to have been caused by the ehrlichia species E.
Even more surprising is that the rapid spread and
reports of the disease have only occurred in the last few years. Today it
has been and continues to be reported in all 50 states, Canada, Europe,
Asia, South America and Africa.
Ehrlichiosis is related to
Mountain Spotted Fever and shares similar signs, though rarely does a victim
of ehrlichiosis display the rash that is associated with RMSF. Lyme disease
also shares some of the same signs, but technically is in a separate
category. Lyme disease is caused by a spirochete (a spiral shaped bacteria)
and although it is transmitted by ticks, as are most of the rocketries, Lyme
disease is sensitive to a wider range of antibiotics, and Lyme disease has
never been linked to fatalities as are many of the rickettsias. The
rickettsial group is unique in that it's members share some traits of a
virus, and some traits of a bacteria, but they are classified with bacteria.
While doxycycline is frequently used to treat Lyme
disease other drugs have been used. Amoxicillin is a recent trend in the
treatment of Lyme disease but has no effect whatsoever on ehrlichiosis. As
both Lyme disease and ehrlichiosis share some signs a misdiagnosis of
ehrlichia as Lyme disease could prove fatal to both dogs and humans if not
treated with the proper drug.
Rickettsias actually parasitize the white blood
cells, which is why they are so devastating to their victims. Essentially,
they cripple the immune system by inhibiting the basic function of the bone
marrow - that of making new cells to replace old and dying cells.
Once a human or animal is stricken with
ehrlichiosis, white cells die off faster than the bone marrow can replace
them. These dead cells migrate primarily to the spleen which enlarges as a
result. Frantically, the bone marrow works to form new, healthy cells. In
its haste, it sends out immature cells which do not work efficiently. Quite
often these immature cells are almost indistinguishable from those seen in
leukemic patients. Advanced Ehrlichiosis is, in fact, often misdiagnosed as
leukemia or lymphosarcoma.
To complicate things further, ongoing research
suggests that chronic ehrlichiosis may lead to various cancers, especially
leukemia and lymphosarcoma. There is speculation that it may predispose
animals to other forms of cancer as well. Because of its effect on the
nervous system, ehrlichiosis is also sometimes misdiagnosed as brain cancer.
It does, in fact, affect many dogs neurologically and can cause seizures,
problems with coordination, changes in temperament, or obsessive-compulsive
behavior (such as repeated licking or other repetitive behaviors.)
Causes of death by ehrlichia are usually due to
internal hemorrhage including hemorrhage into the brain, severe autoimmune
disease, multiple secondary infections due to a compromised immune system or
complete failure of one or more internal organs such as heart, liver,
HOW IS IT TRANSMITTED?
With the exception of E. risticii, most
rickettsias are believed to be spread through contact with ticks. E.
risticii is particularly difficult as no vector (the insect agent of
transmission) has been clearly identified. Ongoing research indicates that a
tick could be implicated but a variety of possible vectors exist. Flies,
mosquitoes, chiggers, and fleas, are all being considered as possible insect
Carriers (reservoirs) of the disease may include
mice, rats and other mammals who have constant exposure to various insects
(but are themselves unaffected by the disease). It was once thought that
cats and even dogs could act as reservoirs for E. risticiiand not
develop signs of disease. In the last few years this has not proven to be
consistent as more and more domestic dogs and cats have developed serious
illness after natural infection with E. risticii.
Newly infected domestic animals (who may ultimately
succumb to the disease) may serve as carriers for insect vectors, who then
pass the infection to another animal. At least one of the species, E.
risticii, can be passed through the placenta to puppies. It can also be
passed from infected donor animals used in veterinary clinics. None of the
species are thought to be passed through breeding, but we have been unable
to locate any current research in this area.
The two species that have, to date, been most
commonly reported in dogs are E. canis and E. risticii. It
is possible to be infected with both species which presents a particularly
nasty challenge. It is fortunate that both respond to the same method of
There is no breed that has shown either a greater
or lesser immunity to the disease and there are a great variety of breeds,
including mixed breeds, that have contracted
While it was initially found primarily in the
Southwestern States, today it is found throughout the US. The human form has
had the highest number of reported cases in Wisconsin and Minnesota but it
too is found in many other locations in the US.
It should also be noted that it has been fatal in
humans whereas Lyme disease has yet to
claim its first victim.
THE STAGES OF EHRLICHIOSIS
The disease typically courses through three stages.
The first is the early or acute stage (which usually mimics a mild viral
infection.) The signs in this stage may be very subtle and could go
unnoticed. Without proper treatment the animal will go on to a
sub clinical (second) stage or may advance to the chronic (final) stage. During the acute
stage most, if not all, damage is reversible and a full recovery is
possible. It is during this stage that treatment is most effective, which
emphasizes the need for early detection.
Once the chronic stage is reached, the rickettsial
organism has taken up residence within the bone marrow. At this point the
damage done is often irreversible. It is not unusual for dogs in this final
stage to suffer massive internal hemorrhage, or succumb to sudden stroke,
heart attack, renal failure, splenic rupture or liver failure, resulting in
death. A peculiarity about the disease is - these dogs often do not look or
act as though they are in a terminal stage of disease until their final
DETECTION OF EHRLICHIA
If there is any one element of this disease that makes
it especially deadly, it is the ability it possesses to mimic other
diseases. Perhaps the best description of ehrlichiosis is "the AIDS of
the canine world". The detection of
the disease has, so far, only been successfully accomplished through IFA
(indirect fluorescent antibody test) which detects the presence of
antibodies. This test is, however, not infallible; dogs sometimes test
negative in the acute phase due to their immune system's delay in forming
antibodies. They may also test negative, or with a low titer, when in the
chronic stage (the immune system at this point may be giving up the battle.)
Regardless of the what the titer is, any positive
should be considered indicative of infection and treated quickly and
aggressively. A dog with a negative titer who has signs should still be
treated, then re-tested at a later date.
Although E. canis and E. risticii
appear to be the most common species to infect dogs, other species are out
there which won't be detected if the laboratory is testing strictly for E.
canis or E. risticii. (Another reason to treat the signs even
if the titer test is negative.) CBC panels have been used but they are too
non specific to be reliable. There are many cases where a dog's CBC has been
"within normal limits" yet the dog died of
CBC Panel abnormalities are often so borderline,
they may be overlooked by the vet as inconsequential. An example could be a
dog who appears to have sufficient platelets, yet is showing signs of
internal hemorrhage (blood in urine, bruising on mucosal surfaces, coughing,
bloodshot eyes etc.) This can happen because the platelets have lost their
ability to function normally - they can actually lose their adhesiveness
which hinders their ability to form a normal blood clot.
When abnormalities are seen in a CBC Panel, they
may include a reduction in platelets, mild anemia, high WBC (usually in new
infections), low WBC (usually in chronic cases), high sedimentation rate
(due to dead cells outnumbering healthy cells), high alkaline/phosphatase
ratio, and other slight abnormalities. Kidney function tests may show high
BUN and creatinine. In these cases, the diet should be altered to lessen the
strain on the kidneys.
The following laboratories are experienced in
running the IFA test for various species of ehrlichia, including E.
risticii. In some laboratories discounts may be available, either when
testing for several species of ehrlichial infection in the same dog (a
"rickettsial panel") or if multiple dogs (such as in a breeding
kennel) are tested at the same time ("bulk testing"). Be sure to
inquire about any discounts before blood is sent.
Blood must be spun down to separate the serum
component which is then shipped via overnight mail in a cold pack. Direct
any questions about this procedure to the laboratory where you are sending
Colorado State University's Veterinary
University of Illinois
Laboratory of Veterinary Diagnostic Medicine
ATTN: Dr. Kakoma
P.O. Box "U", 2001 S. Lincoln
Urbana, IL 61801
PH: 217/333-1620 or 217/333-1859
Protatek Reference Laboratories
ATTN: Dr. Cynthia Holland
574 E. Alamo Street
Chandler, AZ 85225
Dr. T. McElwain
Washington State University
Vet Diagnostic Lab
Pullman, WA 99164
Dr. E.B. Brietschwerdt
Dr. M.G. Levy
North Carolina State University
College of Vet Medicine
4700 Hillsborough Rd.
Raleigh, NC 27606
Dr. D. Huxsoll
Louisiana State University
School of Vet Medicine
Baton Rouge, LA 70803
SIGNS OF THE DISEASE
Perhaps the greatest challenge in battling
ehrlichiosis is in detecting and accurately assessing the signs. This has
been one of the major reasons for the disease being under-reported and
misdiagnosed. In most cases the early signs are very subtle. In all cases
the signs mimic those caused by other diseases.
In the acute phase of infection, ehrlichiosis
appears much the same as any viral infection. The animal often runs a fever,
may lose his appetite and/or act depressed, the eyes may have a glassy
appearance, etc. These signs may even disappear of their own accord in a few
days time. Animals who are especially stoic may pass through this phase
without anyone even noticing. This stage of the disease almost always clears
up without treatment. It is, however, during this stage that treatment can
be most effective in eliminating the disease.
Virtually any unusual sign is worthy of note as
there are generally more than one. The animal may act depressed or tired
with a diminished interest in playing. Acute infections of E. risticiiwill
sometimes involve diarrhea and/or vomiting (often this is vomiting of bile
only). The animal usually refuses food for a few days, may lose weight, and
will probably want to be left alone. E. risticii is often
misdiagnosed as parvo or corona infection, and occasionally the signs of E.
risticiiare very similar to those of kennel cough.
It is when ehrlichiosis is not treated in this
first stage with the proper antibiotics that it goes on to wreak havoc in
the system of its canine victim. The following list of signs should be
carefully reviewed as recognition of the signs will more than likely be the
first indication of the disease. Remember that while few dogs display all of
the signs, most will show several. Again, stoic dogs are the most difficult
to diagnose; trust your instincts and remember that you are the best judge
of what is normal in your own dog and what isn't. In one case of a Border
Terrier who had both E. canis and E. risticii, the only
sign noticed by the owner was the dog lost interest in play - something he
had always enjoyed to the utmost. As we have indicated, any change in
behavior is enough to warrant precautionary measures.
Breeders may observe unique signs due to their
experience with pregnant and nursing bitches as well as puppies. A female
dog with signs previously too subtle to be noticed, may develop serious
illness during pregnancy, or she may deliver dead or ailing puppies. In
these cases, breeder and veterinarian must work in cooperation with one
another in order to make the correct diagnosis.
We would like to thank and are eternally grateful
to Susan Netboy for the excellent job she has done in compiling the
following list. Susan is very active in greyhound rescue and was one of the
first to realize the scope of ehrlichiosis as well as babesiosis in rescued
greyhounds. It should be of concern to all that greyhounds make up a very
large percentage of the blood donor dogs, both at university veterinary
school hospitals, and at many veterinary clinics. Rickettsias are readily
spread through blood transfusion.
Information gathered by Susan
EHRLICHIOSIS is an infectious blood disease. A
reduction in cellular blood elements is the primary characteristic of the
disease. Although the organism lives and reproduces in the white blood cells
(leukocytes); it has a particularly devastating effect on the lymphatic
system and will ultimately affect multiple organs, systems, and cells:
respiratory, circulatory, central nervous system, kidney, brain, liver,
Additionally, the severe depression of the immune
system created by the disease opens the door to secondary bacterial
infections and other complications. Because the onset of visible signs is
likely to be gradual in the chronic phase and subtle in appearance,
alertness to the following conditions is imperative in order to catch the
disease while it is still treatable:
- labored breathing
- intermittent fever
- muscle wasting
- discharge from nose or eye
- weight loss
- increased thirst and urination
- sensitivity of the skin
- head tremors
- neck or back pain
- bleeding tendencies
- pallor due to anemia
- retinal hemorrhages
- bleeding into the skin
- nose bleeds
- spontaneous bleeding
- abdominal tenderness
- swelling of the legs
- swollen lymph nodes
Certain features of ehrlichiosis may mimic the
- systemic lupus erythematosus
- immune mediated diseases
- cancer of the spleen or liver
- Valley Fever
- plasma cell myeloma
It is recommended that ehrlichiosis be ruled out
before accepting these diagnoses as a definitive cause of the illness or
condition. Ehrlichiosis is known to be prevalent in racing greyhounds; there
is no question amongst veterinarians who have dealt with the disease that it
must be taken seriously and aggressively treated. Testing is simple and
definitive; a positive titer at any level needs to be treated. Very good
results can be obtained with readily available, inexpensive treatment of a 7
to 8 week course of tetracycline or doxycycline at the correct dosage. (For
further information contact: Susan Netboy at (800) 446-8637) Contents
Copyright (c) 1995, Greyhound Friends For Life. Last Modified: August 15,
TREATMENT OF EHRLICHIOSIS
Due to the rapid spread and inadequate publicity the
single biggest failure has been the failure to recognize and test for the
disease. Perhaps the strongest recommendation that can be made is to
eliminate ehrlichiosis first as a possible cause by treating with
appropriate antibiotics to see if the animal responds. If an animal has any
of the above signs an excellent path would be to take blood for a Indirect
Fluorescent Antibody (IFA) test and start the animal on doxycycline
If the titers return as negative, but the animal is
responding to treatment, he should be kept on the antibiotic and re-tested
in a couple of weeks. The IFA test looks for the presence of antibodies
produced by the dog's immune system and it may take as long as 30 - 45 days
for the immune system to respond with the production of enough antibodies to
detect. As doxycycline does not affect the production of antibodies it will
not interfere with the test results.
We strongly advise against waiting for a
positive result before treating with doxycycline. Vets should also be
cautioned about the use of steroids in a dog who may have ehrlichiosis. If
disease is the suspect then treat with doxycycline. Although some
chronically-infected dogs may need steroid treatment, this should always be
done in conjunction with doxycycline treatment and only as a last resort
measure. In cases where the vet feels more than one disease may be involved,
ehrlichiosis should be given the first priority.
In acute cases there is usually a dramatic response
to treatment. A case in point involved a Border Terrier owned by one of the
authors. He presented with signs consistent with renal failure, and renal
failure is not usually treated with doxycycline. However, the owner was
aware that the dog had been exposed, and the signs had come on quite
suddenly. There was also apparent (though slight) enlargement of the spleen
and liver. The vet then reluctantly agreed to treat with doxycycline along
with other supportive therapy.
When the test results came back 48 hours later, the
vet was alarmed at the apparent indication of chronic renal failure.
However, re-examination and testing of the patient showed dramatic
improvement - 2 days on doxycycline had brought kidney function back within
the normal range, the heart rate had returned to normal, and dehydration was
no longer evident. Subsequent IFA titer tests showed the dog was indeed
positive for both E. canisand E. risticii. Due to the
decision to treat immediately, this dog is still alive, enjoys excellent
health, and has normal kidney function at age 7 1/2 years. This also makes
the drug a diagnostic tool as well as treatment. If the signs disappear with
treatment it is almost a virtual certainty that the dog has been infected
and blood tests should be run to make the confirmation.
Most cases have shown a good response to treatment
with the tetracycline family of antibiotics. Doxycycline is the preferred
drug as it has less potential side effects and better penetration of certain
bacteria (Merck). Inoculations as well as injectable antibiotics should not
be administered to a dog suspect for ehrlichial infection, as reactions have
been reported, some of which proved fatal to the patient (the immune system
is already taxed due to the action of the disease.)
Another drug, Imizol®, has also proven very
effective, but unfortunately it is not readily available in the US and is
still considered experimental. (Since the article was written in 1996 ,
unfortunately, little has changed. However, one important change is the fact
that Imizol is now available and your vet should be able to easily obtain
it. This drug is given by injection in a series, normally, of two shots two
weeks apart. - Bob Wilson 1/14/2000).
The suggested treatment with doxycycline has been 5
to 10mg per day per Kg. (according to the Merck Manual.) Some dogs have been
treated at a rate of 20 mg per kg body weight per day (or 200 mg for the
typical 22 pound dog, divided into two daily doses given 12 hours apart)
with excellent results. Most cases have shown that the higher dosage is more
effective, but its use will be dictated by the animals tolerance. It should
be administered for at least a 6 week period. Due to the high dosage Merck
also suggests vitamin supplementation with vitamins B and K due to the
reduction in the animals ability to synthesize those vitamins in the large
intestine. In some cases wrapping the tablet in a piece of bread or adding
to rice will facilitate administering the drug as well as helping to prevent
nausea which may occur in some animals on the high dosage.
We hope that this will be a help in spotting the signs
and treating ehrlichiosis early and effectively. More importantly, we hope
that it will create an awareness in owners, breeders and veterinarians to
watch for the subtle signs of this disease. If caught early it is curable.
For those who read this and can influence
pharmaceutical companies to develop a vaccine as has been done for
disease, we will consider our mission complete.
the many veterinarians, veterinary
technicians, breeders and owners who have shown genuine concern for the
animals suffering from ehrlichiosis, and share our determination to push for
more widespread testing, treatment, and hopefully a vaccine. We would also
like to make a special mention and thanks to Michelle Tjaden who, in
addition to providing a great deal of reseach information, had the first dog
(Border Terrier) from which the first culture of E. risticii was
grown by Dr. Kakoma. We would also like to thank Barbara Mair who has
researched this disease with a vengeance and was instrumental in getting DNA
testing underway; and to Dr. Jutta Hammermuller, who, working closely with
Mrs. Mair and Dr. Kakoma, gave generously of her time and expertise to
figure out how to conduct PCR/DNA tests on dogs.
A very special thanks has to go to Dr. Ibulaimu
Kakoma who is an Associate Professor of Microbiology/Immunology at the
College of Veterinary Medicine at the University of Illinois Champaign. Dr.
Kakoma is a Doctor of Veterinary Medicne as well as a microbiologist and is
an expert on the subject of tick borne diseases. He has written many
articles on the subject of ehrlichiosis and continues his research today. He
took many hours out of his busy schedule to discuss various issues and
agreed to write the Foreword at the beginning of this article. Dr. Kakoma is
fully dedicated to the eradication of ehrlichiosis and has been instrumental
in providing technical assistance, not only for this document, but to our
mutual attempts to attract and convince drug manufacturers to develop a
WE DEDICATE this paper to our memories of
Saucy, Jake, Bonnie, Clancey, Duke, Keeley, Pajti, Emma, Penny and the many
many other beloved pets who lost their battle with ehrlichiosis, and left an
empty spot in the hearts of their owners that can never be filled. All of
these dogs succumbed to an insidious killer we now know as ehrlichiosis
because, at the time, there was not enough widespread knowledge to prevent
it. We created this paper to provide that knowledge to help prevent others
from the same fate and dedicate this paper to those stoic little animals so
they will not have died in vain.
Bob Wilson - Border Terrier Owner
In the process of putting this document together I
was asked by several people around me as to why I seemed so focused on the
subject. Many who have experienced this type of tragedy would prefer to move
on and try to forget the incident. My answer was that I guess that I
preferred to learn from history rather than be doomed to repeat it.
There is no question that it is a valid answer but
the real reason was that you had to know Jake. She came into my life at a
time when turmoil was the norm and I was finding myself emotionally drained.
While Jake's arrival five and a half years ago didn't solve the problem it
made my life bearable and gave it a purpose. I found myself changing my
lifestyle to adapt to hers. We were constant companions and virtually
inseparable. Jake went to the office with me, spent countless hours in the
car with me and slept with me. It was almost a joke amongst many of my
friends as they knew that if they invited me somewhere where there was any
possibility of bringing Jake that she had to have an invitation or I might
not show. She gave me more love than I knew existed and in return I gave her
more love than I knew I had. She read me like a book and knew when I needed
a friend and when I needed to go play ball with her. She was my best buddy.
On October 30, 1995 that relationship came to an
abrupt and sad end with her death from what we now know as ehrlichiosis. It
was only 30 days prior to her death that I learned about this insidious
killer and by then it was too late. If life was 36" in diameter I had
just had a 34" hole blown in mine. There has never been the death of
any living thing that has so profoundly affected me. It is a loss that still
haunts me to the depth of my soul.
Because there seemed to be no clear-cut reason for
the disease I went on a quest to learn all I could about it. Unquestionably
Jan Hendricks, a co-author of this document, was my major source of both
information and consolation. Jan is a Border Terrier breeder and was where
Jake came from. Her dedication to the breed and maintaining its' high
standards is nothing short of awesome. It was through our discussions that
we decided to try to put all of the known information in one place. This
document very simply would not be if it were not for her dedication.
There are many others who provided information to
this document that space does not allow us to mention. Several, however,
simply have to be recognized. Susan Netboy who is involved with Greyhound
Friends for Life which is a rescue organization has done a great deal
of work in "spreading the word". A significant part of her work on
ehrlichiosis is contained in this article. A very special thanks to
Adame who runs the "Tick Net" on the Internet. That group now has
over 55 members who regularly share information on ehrlichiosis and
babeiosis and it's treatment.
We hope that this document will help you avoid the
pain , sorrow and problems that we have all experienced with this silent and
What it is
Ehrlichiosis, often called tick
fever or tropical canine pancytopenia, is a tick-transmitted disease
affecting dogs. The brown dog tick carries the organism causing Ehrlichiosis
and transmits the disease while feeding on the dog’s blood.
The disease has two phases,
acute and chronic. The acute phase occurs 1-3 weeks following tick exposure.
Clinical signs of illness are rather nonspecific and may include
listlessness, swollen lymph nodes, anorexia, fever, and discharge from the
nose and eyes. The signs of the chronic phase may include those mentioned
for the acute phase plus nosebleeds or other abnormal bleeding and weight
loss. The chronic phase may occur several months following the acute phase.
In both phases, the damage done
to the body relates to destruction and decreased production of all blood
cells (red blood cells, white blood cells, and platelets). This leads to
anemia, decreased resistance to disease, infection and abnormal bleeding.
German Shepherds seem especially susceptible to the disease.
Although clinical signs and a
history of prior tick infestation are helpful, accurate diagnosis depends
upon blood testing.
The acute phase of the disease
usually responds to treatment within a short period of time. The chronic
phase is difficult to treat and may require several months of therapy.
Treatment for both phases usually involves specific antibiotics, but may
include other supportive care.
Unfortunately, the chronic form
of the disease can be fatal.
The best prevention of the
disease is to keep your dog free of ticks. This should include checking the
skin daily for ticks, treating the dog with tick products (tick dips,
powders/sprays, or baths), and having your home and yard sprayed for ticks.
About The Brown Dog Tick….
- It is the most widely
distributed of all ticks in the United States.
- The preferred host is the dog
and it seldom attacks man or other animals.
- It feeds on the blood of dogs.
- It infests dog kennels, runs,
backyards, and will readily infest the home. Usual hiding places in the
home include baseboards, window casing, furniture, curtains, and carpet.
- The tick life cycle has three
stages, with each stage requiring a blood meal before maturing to the
next stage. The complete life cycle may be as short as two months, or as
long as two years.
- Controlling the brown dog tick
requires treatment of infested premises by the homeowner or a pest
control operator, as well as treatment of the dog. Your veterinarian can
advise you as to proper treatment methods for your dog.
This information is supplied by
the Arizona Veterinary Medical Association in cooperation with your
Antibiotics (Monodex, Vibramycin, Terramycin)
Veterinary Services Department, Drs. Foster
& Smith, Inc.
Tetracyclines are antibiotics
which is available in multiple forms. Does not kill bacteria, but slows their
growth. Not for use in pregnant or nursing dogs or puppies.
Doxycycline, Oxytetracycline, Tetracycline
Monodex, Vibramycin, Terramycin, Achromycin (for eyes), Panmycin Aquadrops
Albaplex contains tetracycline and novobiocin
Delta Albaplex contains tetracycline, novobiocin and prednisolone
Tablet, capsule, oral suspension, powder for injection, and as an eye drop
Unless otherwise stated by the manufacturer, the products should be stored
in tight, light-resistant containers at room temperature. Once the powder is
reconstituted (mixed with sterile water) it should be stored at room
temperature and used within 12 hours for intravenous
(IV) injection or 24 hours for intramuscularly (IM)
Treatment of spirochetes (like the Lyme disease
organism), Chlamydia, Rickettsia (like Ehrlichiosis and
Rocky Mountain Spotted Fever), and gram positive
and gram negative bacteria. Some bacteria are
developing resistance to tetracyclines. Tetracyline
has been used with variable results to decrease facial staining from tears,
although it is not approved for this use.
Tetracycline is FDA approved for use in dogs and
cats. Oxytetracycline is approved for use in large animals. Doxycycline is
not approved for use in veterinary medicine, however, it is a common and
accepted practice to use oxytetracycline and doxycycline in dogs and cats.
Available by prescription. Tetracycline antibiotics are bacteriostatic which
means they work by interfering with the growth cycle of the bacteria
allowing the body time to fight the infection.
Dose and Administration
Dogs: Oxytetracycline 9 mg/pound by mouth (capsules) every 8-12 hours.
Tetracycline 10 mg/pound by mouth (liquid, tablets, oral suspension) every 8
hours by mouth. For facial tearing in dogs use 2-4 mg/pound daily or 50 mg/dog
per day. Results vary. Doxycycline 2-5 mg/pound every 12-24 hours by mouth
(tablets, capsules, oral liquid).
Cats: Oxytetracycline and tetracycline 9 mg/pound every 8-12 hours by mouth.
Doxycyline 2 mg/pound every 12 hours by mouth (tablets, capsules, oral
suspension). Type used and the duration of treatment depends on the disease
being treated and the response to treatment.
May see vomiting, diarrhea, or lack of appetite. Cats have more difficulty
tolerating tetracycline and may also show signs of stomach pain, fever, hair
loss, and depression. Rarely seen are photosensitivity,
damage, and blood disorders.
Not for use in animals hypersensitive (allergic) to
Not for use in pregnant,
nursing animals, or growing animals as it may slow bone growth and discolor
teeth (turn teeth yellow, brown, or gray) in young animals.
Use with caution in animals
with liver or kidney disease and if using other medications that affect the
liver or kidney.
Delta Albaplex has the
maximum benefit if used in the first 48 hours of treatment then Albaplex
should be used for the rest of the treatment.
or Food Interactions
Products given by mouth such as antacids, vitamins, minerals, Pepto-Bismol,
or Kaopectate may decrease the absorption of the tetracycline antibiotic. It
is recommended to give these products at least 3 hours before or 2 hours
after the tetracyclines.
In humans, tetracycline has
caused an increase in serum (blood) levels of digoxin (a heart medication)
that may last several months after discontinuing the tetracycline.
tetracycline are better absorbed on an empty stomach. Doxycycline is
absorbed even with food in the stomach.
Side effects may be reduced
if given with food.
Unlikely after oral (by mouth) overdoses. May see vomiting, lack of
appetite, or diarrhea.
Holly Frisby, DVM
Veterinary Services Department, Drs. Foster
& Smith, Inc
Haemobartonellosis is a tick transmitted (and
sometimes flea transmitted) disease that affects both cats and dogs.
Haemobartonellosis targets the red blood cells which are responsible for
carrying oxygen. In cats, it is called feline infectious anemia.
What causes haemobartonellosis
Haemobartonellosis is caused by Haemobartonella
canis and H. felis. H. canis and H. felis are
not typical bacteria. They belong to a group of microorganisms called mycoplasma,
which are the smallest free-living type of 'germs'.
How are H. canis and H.
Fleas and ticks become infected with Haemobartonella
by feeding on an infected animal. When the flea or tick then feeds on another
animal, the Haemobartonella are passed on. Because Haemobartonella
live in the blood cells, they could be spread via a blood transfusion from an
infected animal to a noninfected one. In the cat, Haemobartonella can
also be spread from the queen (mother cat) to her kittens. There is evidence
bitches can also pass Haemobartonella to their puppies, but is has not
What are the symptoms of
haemobartonellosis in dogs?
In the dog, the disease is generally not apparent
unless the dog has previously had its spleen removed (splenectomy),
has a suppressed immune system (e.g., from taking
cancer chemotherapy), or is infected with other organisms such as Ehrlichia.
The spleen is responsible for filtering the blood and its job is to remove and
destroy damaged red blood cells, like those seen in haemobartonellosis. That is
why a dog without a spleen is more susceptible - there is nothing to remove the
infected cells (and the Haemobartonella) from the blood stream.
Since one tick could be infected with and transmit
more than one disease (e.g., haemobartonellosis, ehrlichiosis, babesiosis), it
is not all that uncommon to see a dog infected with more than one of these
diseases at a time.
How is haemobartonellosis
Sometimes the organism can be seen inside cells on a
blood smear. To find them, a small drop of blood is spread over a microscope
slide, stained and examined under the microscope. The number of organisms in
the blood stream can fluctuate dramatically. There can be many observed in one
sample, and a sample taken two hours later may reveal none. .
How is haemobartonellosis
Antibiotics such as tetracycline, oxytetracycline or
doxycycline are given for three weeks. In some animals it is necessary to give
one or multiple transfusions.
How is haemobartonellosis
As with other diseases transmitted by fleas or ticks,
flea control and tick control are the foundations of prevention. Products which
repel and kill ticks and fleas such as Bio Spot for Dogs are good choices. For
dogs, tick collars containing the active ingredient amitraz are also used,
sometimes in conjunction with Bio Spot in those areas with high tick infestation.
Can people get
There have been no reported cases of
haemobartonellosis in people.
Holly Frisby, DVM
Veterinary Services Department, Drs. Foster
& Smith, Inc.
is a one-celled parasite that is transmitted by ticks, usually the Brown Dog
Tick, Rhipicephalus sanguineus. Because of the long time interval
between becoming infected and developing illness, this disease is not just
seen during the tick season, but all year round. It is not a very common
disease in the United States, but when it does occur it’s usually in Texas
and the surrounding states. This parasite infects dogs, coyotes, and fox.
What are the signs of disease
caused by H. canis?
Most infections with H. canis do not cause
illness. It can cause serious disease, however, in animals with concurrent
disease such as ehrlichiosis and babesiosis, or in animals with suppressed immune
systems. Signs of disease include fever, loss of weight, loss of
appetite, nasal discharge and weakness of the rear limbs. A mild anemia
and bloody diarrhea may also be seen. As the disease progresses, lameness,
severe muscle pain, and an inability to rise are often observed. These signs
may occur on and off for years. To better understand how H. canis
causes these signs, let’s look at the life cycle.
What is the life cycle of this
When an infected tick is eaten by a dog, H.
canis is freed and migrates through the dog’s intestine to the liver,
spleen, lymph nodes, heart
and muscles. Inside the cells of these organs, the parasite reproduces by
dividing and eventually ruptures the cell. The parasite then moves into
different cells to continue the process of maturing and rupturing cells. The
damage caused by the rupturing of these cells causes the severe muscle pain.
Eventually the more mature forms enter particular white
When a tick bites the dog, the tick takes in the
white blood cells. H. canis reproduces in the tick, and when eaten,
the tick will infect another dog. H. canis does not move to the
salivary glands of the tick, so it is NOT transmitted by a tick bite –
only by eating the tick.
How is infection with H.
A diagnosis of H. canis infection is made
by microscopically examining the blood and finding the parasite in
particular white blood cells called neutrophils. A great increase in the
number of this certain type of white blood cell is a characteristic sign of
this disease. Finding the parasite in a muscle biopsy
is a very reliable method of diagnosing this disease.
In some severely affected dogs, the point at which
the muscles attach to the bones may become inflamed. These bony changes may
be seen on radiographs (x-rays).
How can infection with H.
canis be treated and prevented?
There is no effective treatment or vaccine for this
disease. Certain drugs such as imidocarb in combination with other drugs
have sometimes been successful in lowering the number of organisms in an
animal. Using supportive care, such as aspirin, some cases will respond but
they will not be cured.
Tick control will be helpful in preventing the
spread of this parasite. Using a tick preventative such as Bio Spot on your
dog would be helpful since the ticks most commonly eaten by a dog are the
ones it finds while grooming.
Georgi, JR; Georgi, ME.
Canine Clinical Parasitology. Lea & Febiger. Philadelphia, PA; 1992;90-94.
Sherding, RG. Toxoplasmosis, Neosporosis, and Other
Multisystemic Protozoal Infections. In Birchard, SJ; Sherding, RG (eds):
Saunders Manual of Small Animal Practice. WB Saunders Co. Philadelphia, PA;
Sousby, EJL. Helminths, arthropods and protozoa of
domesticated animals. Lea & Febiger. Philadelphia, PA; 1982;689-690.
J. S. Mathew, BVSc, MS
& S. A. Ewing, DVM, Ph D
Department of Infectious Diseases and Physiology, College of Veterinary
Medicine, Oklahoma State University, Stillwater, OK 74078-2006
Ehrlichiosis is a disease
that affects a variety of animals including human beings; caused by
obligatorily intracellular bacteria belonging to the genus Ehrlichia
. There are several species assigned to this genus and those for which
the vectors are known are transmitted by ixodid ticks. Ehrlichial organisms
infect predominantly white blood cells of their vertebrate hosts; one
exception isEhrlichia platys which infects dog platelets. The organisms
appear in clusters known as morulae in the cytoplasm of infected cells.
Ehrlichial organisms are classified as agranulocytic
or granulocytic based on the cells they infect and one that infect platelets.
The species currently assigned to the genus Ehrlichia are as follows:
Ehrlichia canis (Donatien
and Lestoquard 1935), Moshkovski 1945
Ehrlichia canis was the
first ehrlichial organism to be discovered and is the type species of the
genus E. canis has worldwide distribution and is the cause of canine
agranulocytic ehrlichiosis. This organism is known to be transmitted
transstadially by the brown dog tick, Rhipicephalus sanguineus under natural
conditions. Dogs are likely to be long term carriers but can be cleared if
treated properly with tetracyclines. E. canis can be cultured in vitro in
mammalian-derived cell line (DH82) and in an invertebrate cell line (IDE8).
Clinical signs of E. canis
Pyrexia (103-1060F), lethargy, anorexia, weight loss, bronchial sounds,
dyspnea, cyanosis and often death if not treated. Hematological findings
include severe thrombocytopenia (<25000/ul), mild anemia, and leukopenia.
Depression, abdominal tenderness, scrotal and limb edema, petechial
hemorrhages of mucus membranes, epistaxis, melena, retinitis leading to
blindness, uveitis, corneal edema, and miosis; neurological abnormalities
include hyperesthesia, anisocoria, and seizures. Hematological findings
include hyperproteinemia, hyperglobulinemia, and hypoalbuminemia.
Anderson, Greene, Jones, and Dawson 1992
E. ewingii is the causative
agent of canine granulocytic ehrlichiosis first identified in 1969 at
Oklahoma State University, Oklahoma, USA and recognized as a distinct
species in 1992. This organism infects neutrophils and eosinophils and
produces a milder disease than that produced by E. canis infections.
Experimental transmission studies suggest that this agent can be
transstadially transmitted by lone star tick, Amblyomma americanum
. This agent has not been cultured in vitro.
Most often asymptomatic and there may be mild fever (102-1030F), anorexia
and lethargy. Hematological findings include mild thrombocytopenia,
leukopenia and mild normocytic normochromic anemia.
Chronic cases are thought to be characterized by arthritis but the
relationship has not been proved experimentally and synovial fluid often
contains granulocytes infected with ehrlichial organisms.
Ehrlichia platys, French
and Harvey 1982
Ehrlichia platys which
infects dog platelets is the only Ehrlichia spp that infect cells other than
leukocytes. It causes infectious cyclic thrombocytopenia (ICT). The disease
is characterized by severe thrombocytopenia(<15000/ul) occurring at
regular intervals. The disease is often asymptomatic but thrombocytopenic
animals may hemorrhage after accidents or during surgery. The vector for
this agent is not known, though R. sanguineus is suspected.
Holland, Ristic, Cole, Johnson, Baker, and Guetz 1985
Ehrlichia risticii is the
causative agent of Potomac horse fever or equine monocytic ehrlichiosis.
Natural infections were also reported in dogs with symptoms resembling E.
canis infection. This organism is very closely related to Ehrlichia sennetsu
(see below). Potomac horse fever is prevalent in midwestern and northeastern
United States and also reported from Europe and India. The mode of
transmission of this agent is unknown, but recent reports suggest oral
transmission. Trans-placental transmission of this agent also has been
reported. Infections are more prevalent during summer months and have about
5-30% mortality rate.
enteritis, watery diarrhea, colic and laminitis. Hematological findings
include thrombocytopenia and leukopenia.
Ehrlichia equi, Lewis,
Huxsoll, Ristic and Johnson 1975
Ehrlichia equi causes
equine granulocytic ehrlichiosis originally reported from the Sacramento
Valley in California, USA. This organism is closely related to or possibly
identical with Ehrlichia phagocytophila and the human granulocytic
ehrlichial (HGE) agent (see below).The mode of transmission of this agent is
unknown, but Ixodes spp. are suspected as vectors. E. equi infections
normally occur during fall, winter and spring. The laminitis commonly
observed with E. risticii infection is absent in equine granulocytic
Fever, anorexia, petechial
hemorrhages and edema of legs
Ehrlichia bovis (Donatien
and Lestoquard 1936), Moshkovski 1945
Ehrlichia bovis is the
cause of bovine mononuclear or agranulocytic ehrlichiosis in cattle. The
disease is reported from Africa, Middle East, India and Srilanka, but not
reported from USA. This agent was originally isolated from circulating
monocytes of Moroccan cattle to which Hyalomma spp. ticks were transferred
from cattle imported from Iran. The disease is known as "Nopi" or
"Nofel" in West Africa.
Clinical signs include
fever, anorexia, incoordination and enlarged lymph nodes
Ehrlichia phagocytophila (Foggie
1952), Philip 1962
Ehrlichia phagocytophila is
the bovine/ovine granulocytic ehrlichial agent reported from Great Britain.
This agent is now thought to be similar or nearly identical to E. equi or
HGE. Cross-immunity between the bovine and ovine strains is incomplete.
About 6-50% of granulocytes show the parasite during the acute phase of
infection. The organism is transmitted by the sheep tick, Ixodes ricinus.
Signs include fever,
reduced milk production, weight loss, and perhaps abortion. Hematologic
findings include leukopenia and thrombocytopenia
Ehrlichia sennetsu, Missao
and Kobayashi 1956
The disease caused by this
agranulocytic ehrlichial agent has been known to exist in southwest Japan
since the 19th century. The disease has been variously known as Hyuganetsu
disease, sennetsu ehrlichiosis, glandular fever, and infectious
mononucleosis. Mice are highly susceptible to this agent and are routinely
used for laboratory cultivation of the parasite. This agent is serologically
related to E. risticii. The vector is unknown, though eating of a particular
fish has been suspected to be a source of infection.
Acute febrile illness,
lethargy, weakness, diarrhea and generalized lymphadenopathy. Hematological
findings include lymphocytosis as the most consistent finding.
Anderson, Dawson, and Wilson 1991
Ehrlichia chaffeensis is
the causative agent of human (predominantly agranulocytic) ehrlichiosis. The
first case was reported from Michigan, USA, in 1986. This agent infects
predominantly agranulocytes but is thought to infect granulocytic series of
cells occasionally. Disease can be fatal in immuno-compromised patients.
Dogs can be experimentally infected with this agent. White-tailed deer are
likely reservoir hosts and experimental transmission of this agent between
white-tailed deer by the lone star tick, Amblyomma americanum, has been
demonstrated. E. chaffeensis is serologically closely related to E. canis
and E. ewingii. This agent has been successfully cultured in vitro in DH82
Fever, headache, malaise,
myalgia, inappetence, nausea, vomition, renal failure, and encephalopathy.
Hematological findings include thrombocytopenia and leukopenia; serum
chemistry shows elevated hepatic aminotransferase levels.
ehrlichial agent specifically infects human granulocytes and was first
reported from Upper Midwest, USA in 1990. The agent is found by 16S rDNA
analysis to be very closely related to E. equi and E. phagocytophila. HGE
can be experimentally transmitted by the black-legged tick, Ixodes
6). The disease caused by HGE can be fatal if not diagnosed and treated
Fever, anorexia, headache,
confusion and neurological abnormalities in advanced stages.
Clinical signs with
hematological findings are very useful in the diagnosis of ehrlichiosis.
Confirmed diagnosis is by demonstration of morulae in a peripheral blood
smear, which is often difficult. Serology using IFA or FIAX can be used for
the diagnosis of agents for which antigens are available; they include all
the agranulocytic ehrlichial agents (except E. bovis), E. platys, E. ewingii
and E. equi. Modern techniques like polymerase chain reaction (PCR) are very
useful for the accurate diagnosis of ehrlichial infections of all types.
are the drug of choice for treating infections caused by all species of
Ehrlichia. They are very effective and can completely eliminate the
organisms if treated properly and to date no drug resistance has been
reported. Other antibiotics, like chloramphenicol and rifampin, are also
effective against ehrlichial agents.
Effective vaccines are
Since ticks are the major
vectors in most cases, tick control is essential in the prevention of
ehrlichiosis. Prompt treatment of vertebrate hosts with correct dosage of
antibiotics will eliminate infection and prevent carrier status.
What Makes Them Tick?
Drs. Foster & Smith, Inc.
The word tick means different things to different
people. Many individuals actually have an 'acarophobia' or fear of ticks.
To us at Drs. Foster and Smith, Inc. who live among the great woods of
Northern Wisconsin, ticks have other meanings. The first emergence of
ticks is a sure sign of spring. They are the one indication that we can
always count on. The World Championship Tick Races are held in the nearby
town of Park Falls, Wisconsin. Literally, hundreds of participants enter
this annual event. Their prized ticks are placed at the center of the
arena and the first tick to exit the ring is declared the winner!
What are ticks?
Ticks are not insects like fleas, flies and
lice, but are arachnids like mites and spiders. There are approximately
850 species of ticks worldwide. Scientists have classified ticks into two
families based upon their structure. The family Argasidae contains the
argasid ticks, which are soft-shelled. Their body lacks a hard shell (scutum)
which is the protective outer covering found on some ticks. Argasids also
have a ventral (on the underside) head and when viewed from above, their
head cannot be seen.
The other tick family is named Ixodidae and
these ticks possess the hard outer covering and therefore are termed
The following is a listing of the common
hard-shelled (Ixodid) ticks and their habitats:
americanum is the Lone Star Tick and is found throughout the
South, east of the Rocky Mountains.
maculatum is the Gulf Coast Tick, and that is where it
albipictus is also called the 'Winter tick' , 'Moose Tick' or
'Elk Tick' and is found in the northern and western United States as well
andersoni is the Rocky Mountain Spotted Fever Tick and
transmits the deadly disease for which it is named.
variabilis is one of the most famous of all. Its name is also
the American dog tick and lives in the entire eastern 2/3 of the United
sanguineus is the king of ticks. It is called the Brown Dog
Tick and is a serious threat to kennels anywhere in the United States.
is a tiny little tick with a huge threat. It is also known as the deer or
black-legged tick. It has one claim to fame and that is it transmits Lyme
All of the above are 'hard-shelled' ticks. There
are more, but these are the most frequently encountered.
The soft-shelled ticks or Argasids are fewer in
number. The one most known is Otobius megnini also known as the spinose
ear tick. It is most common in the southwest and as one might guess,
loves to attach itself and feed on ears.
All ticks have three pairs of legs during the
immature stage and four pairs as an adult. They crawl but cannot fly.
Wings are absent. In addition, ticks possess a sensory apparatus called
Haller’s organ. This structure senses odor, heat, humidity, and you.
This is how the ticks locate their food source. They climb upon tall
grass and when they sense an animal is close by, they crawl on.
What do ticks eat?
A tick's diet consists of blood and only blood.
Your blood, dogs’ blood, cats’ blood, and most blood. The tick imbeds
its mouthparts into the animal's (or human's) skin and sucks the blood.
Except for the eggs, ticks require a blood meal to progress to each
successive stage in their life cycle.
What is the life cycle of
Most ticks are what we call three host
ticks, that is, during their development which takes two years, they feed
on three different hosts. All ticks have four stages to their life cycle:
(seed tick), nymph, and adult. Let's look at the life cycle of the deer
tick, as an example.
Adult female deer ticks lay eggs on the ground
in spring. Later in the summer (depending on moisture and temperature),
the eggs hatch into larvae. The larvae, which are smaller than the period
at the end of this sentence, find an animal (the first host, which is
usually a bird or rodent), live off its blood for several days, then
detach and fall back onto the ground. For deer ticks, this most commonly
occurs in the month of August. In the ground, the well-fed larvae now
molt into the next stage and are called nymphs.
|Each female tick lays
approximately 3,000 eggs.
The nymphs remain inactive during the winter
months and in spring become active. The nymph now finds an animal (the
second host - a rodent, pet or human) and feeds again. Once well fed, the
nymph detaches and falls back to the ground. Here it molts and changes
into an adult. Throughout the fall, both adult male and female ticks now
find another animal (the third host - a rodent, deer, pet or human) and
feed on blood and mate. Once well fed, both males and females fall back
to the ground. The male now dies and the female lives through the winter
and lays eggs in the spring, completing the cycle. If the adults cannot
find a host animal to feed on in the fall, they will survive in the leaf
litter until the next spring when they will feed, mate and produce eggs.
Other species of ticks may be at peak activity
for each life stage at different times of the year than the deer tick we
described. Your local university or health department may have
information on peak tick activity in your area.
What diseases do ticks
Ticks can transmit:
Mountain Spotted Fever
|07 August 2001
Alex Morrow MVB BA PhD MRCVS of the Royal (Dick)
School of Veterinary Studies, Edinburgh, addresses a topical issue with
information from Vetstream’s CANIS
The Pet Travel Scheme has not only opened up
international borders to pets, some diseases never before seen by most UK vets
have made the journey back to our shores. Among the most important exotic
diseases likely to be seen in animals that have returned from abroad are those
transmitted by ticks. Tick activity tends to be greater in summer months, the
time when most dogs are likely to be taken to endemic areas. Several cases of
Babesiosis have been seen in dogs that were taken abroad by their owners –
unfortunately some of them were fatal. Canine ehrlichiosis is another important
tick-borne disease that can also have fatal consequences. The challenge facing
the UK veterinary profession is how to recognize and treat these novel diseases
or to advise owners on their prevention.
This is a serious tick-transmitted protozoal disease
caused by Babesia spp. Dogs imported into areas where the disease is endemic
are particularly at risk and can die within a day of the clinical signs
appearing. Concurrent infection with the tick transmitted rickettsial parasite
Ehrlichia canis is likely.
The geographic distribution of the disease is almost
worldwide in tropical, subtropical and warm temperate climates: Africa, Asia,
Southern Europe, Russia, Central Asia, Central and South America and parts of
the USA. In endemic areas, the prevalence of infection in dogs can be high but
the clinical disease tends to occur primarily in puppies and young adults.
Usually these dogs gradually develop a level of immunity to the disease, but
remain carriers thus providing a reservoir of infection.
Two species of Babesia are involved: Babesia canis and
B. gibsoni. There are three strains/subtypes of B. canis with the most
predominant in Europe being B. canis canis, which is transmitted by the tick
Dermacentor reticulatus. B. canis vogeli, transmitted by Rhipicephalus
sanguineus is found in northern Africa and North America and B. canis rossi,
transmitted by Haemaphysalis leachi occurs in Southern Africa. B. gibsoni is
transmitted by R. sanguineus and H. bispinosa and causes a more chronic form of
the disease. It occurs in North America, North and East Africa and Asia
including India, Japan and parts of China.
The ticks acquire the piroplasms of Babesia spp when
they ingest blood from an infected dog. Sporozoites, the infective stage, form
in the salivary glands of the tick and are transmitted to the dog when the tick
feeds. The parasites invade the dog’s erythrocytes, which then either rupture
or are removed by phagocytosis. Intravascular and extravascular haemolysis and
erythrocyte phagocytosis leads to haemoglobinuria, bilirubinuria and jaundice,
while the inflammatory response contributes to endothelial damage. The
incubation period is 10-20 days. The haemolytic crisis seen in acute infections
results in anaemia, hypoxia and metabolic acidosis. The pathology is that of
anaemia varying from a marked rapidly developing type in highly susceptible
dogs to a more chronic manifestation, with jaundice, in dogs reared in endemic
areas. The inflammatory response probably accounts for the associated
complications. In complicated cases single organ failure tends to predominate,
although multiple organs are often affected. Neurological signs can occur from
the sludging of parasitised erythrocytes in small blood vessels, or from
metabolic changes. Other complications include renal failure and acute
respiratory distress syndrome.
The disease may occur in a hyper-acute, acute or
chronic form. The hyper-acute form is characterised by sudden onset, shock and
rapid death. In the chronic form there is intermittent fever and decreased
appetite with or without jaundice.
Diagnosis of this condition in the UK is obtained from
the history, clinical signs and also haematology.
- Dog has visited endemic area and been exposed to
- May be history of lethargy, exercise intolerance
- Anorexia and weight loss.v
- Neurological signs.
- Signs of haemolytic anaemia, eg depression, ‘water-hammer’
pulse, pale mucous membranes, haemoglobinuria.
- Complications may also be seen including
stomatitis, gastritis and enteritis, respiratory distress, congested
mucous membranes, neurological signs including incoordination, collapse,
nystagmus and seizures, keratitis and iritis, and (rarely) rhabdomyolysis.
Haematological abnormalities include a regenerative anaemia,
thrombocytopaenia and leukocytosis. The definitive diagnosis of
babesiosis is obtained from Giemsa (or Wrights) stained blood smears that
demonstrate the parasite in the erythrocytes. As few organisms are
present in the blood, it is preferable for the sample to be taken from
peripheral capillaries such as in the ear tip or nail bed. Centrifugation
on Percol density gradients enhances the chance of detection. B. canis is
pear-shaped (4-5 um long) and usually occurs in pairs, with up to eight
or more present, whereas B. gibsoni appears singly as smaller (3 um)
round or oval bodies (1 x 3.2 um) but occasionally larger elongate forms
half the width of the cell are present. Serology may be useful in chronic
Therapy is targeted at eliminating or reducing the
parasite load and reversing the anaemia, if severe. In uncomplicated cases
diminazene aceturate (3.5 mg/kg IM) is the drug of choice, but this should not
be used in severe cases. It is effective against B. canis, but less so against
B. gibsoni. It has a low therapeutic index and overdosage results in nervous
signs. Imidocarb dipropionate (5 mg/kg IM) is also effective against B. canis
but not against B. gibsoni (NB a sterile abscess may form at the inoculation
site). Phenamidine isethionate (1.5 mg/kg SC on two consecutive days) is also
used in the treatment of B. canis and B. gibsoni infections.
It should be noted that high doses of diminazene and
phenamide can sometimes induce fatal toxicity in dogs.
Trypan blue (10 mg/kg as a 1% solution given IV)
suppresses parasitaemias and alleviates the clinical signs but it does not
eliminate infection and recurrence of clinical signs can occur.
Blood transfusion is indicated in the severely anaemic
patient (haematocrit value of <0.1 l/l). Fluid therapy may also be required
in severely affected patients to counteract haemoconcentration, acidosis and
shock. It is important to monitor the respiratory rate and pulmonary sounds of
patients receiving fluid therapy – especially if they were already showing
signs of respiratory distress.
Recovery in mild-moderate cases can be apparent within
24 hours of treatment. In dogs with icterus, recovery may be prolonged, but the
prognosis is generally good when treatment has been initiated early and there
are no complications. Dogs may become carriers and recurrence of clinical signs
can occur due to stress. Recurrent infection is possible if the animal has not
been exposed to the parasite for a prolonged period.
Prevention of infection can be achieved by the use of
acaricides and the daily removal of ticks. Prophylactic treatment should be
considered when dogs are taken to endemic areas. Imidocarb dipropionate, 6
mg/kg can prevent the occurrence of clinical disease for 4-6 weeks while
allowing a degree of immunity to develop in exposed dogs. Doxycycline, 5–20
mg/kg daily has been claimed to prevent symptoms developing, especially when
used at the higher dose rate. Vaccines are available in some countries but
strain variation can limit their protective activity.
Ehrlichiosis is a tick-transmitted rickettsial disease
in which, depending on the Ehrlichia spp involved, mononuclear cells,
granulocytes or platelets are parasitised. In dogs raised in endemic areas
infection is common but this rarely develops into clinical disease. However,
disease is very common in dogs imported into endemic areas.
The distribution of Ehrlichia spp is determined by the
distribution of the vector ticks and this includes most of the tropics,
subtropics, warm temperate climates and Finland. E. canis, transmitted by
Rhipicephalus sanguineus, is endemic in Africa, the Middle East, Asia, the
Caribbean, USA, Central America, parts of South America and Southern Europe. E.
ewingii is present in the USA and Northern Europe and E. platys is present in
the USA, Israel, Taiwan and Southern Europe. Although the vector tick species
of E. ewingii and E. platys are not known for certain in the former case it
probably includes Amblyomma and Dermacentor species. R. sanguineus, often
referred to as the kennel tick, can survive over 500 days as unfed adults,
remaining infective for at least 150 days, allowing them to over-winter and
pass on the infection the following spring. The preferred feeding sites of the
adult tick on the dog are the ears, along the back of the neck and between the
toes but in heavy infestations they may be found almost anywhere.
Canine monocytic ehrlichiosis caused by E. canis, is
the most important form of canine ehrlichiosis. It can present in an acute or
chronic form, the latter when severe being referred to as tropical canine
pancytopaenia. The clinical manifestations of canine granulocytic ehrlichiosis,
caused by E. ewingii, are similar to but much milder than the acute form of
canine monocytic ehrlichiosis while canine cyclical thrombocytopaenia, caused
by E. platys, is not usually accompanied by clinical signs.
Infection occurs via salivary secretions when an
infested tick ingests a blood meal. The incubation period of E. canis infection
varies between eight and 20 days followed by acute, subclinical and in some
cases chronic phases. It is an obligatory intracellular parasite multiplying
inside cytoplasmic vacuoles in mononuclear phagocytic cells. Spread
haematogenously, the parasite causes splenomegaly, hepatomegaly and
lymphadenopathy. Vasculitis can develop affecting various organs including the
lungs, kidneys and possibly the meninges. Immune mechanisms play a major role
in the pathogenesis of the disease. Thrombocytopenia, anaemia and leukopenia
are often seen during the acute phase due to bone marrow suppression and may
persist during the subsequent subclinical phase. The disruption of platelets
can result in haemorrhages, especially epistaxis. Severely affected animals are
susceptible to secondary infections.
A lymphoproliferative syndrome can be seen with
persistent latent infection, resulting in the accumulation of large numbers of
plasma cells in various organs including lymphopoietic tissues, the kidneys and
meninges. This chronic form can develop several weeks or even years after the
primary clinical episode and is known as tropical canine pancytopenia. Not all
dogs develop the chronic form of the disease but German Shepherd dogs appear to
be more susceptible.
E. platys causes a cyclical riskettsiaemia of
approximately ten day intervals with thrombocytopenia of diminishing severity
as immunity develops.
Diagnosis of ehrlichiosis from the clinical signs is
difficult as there are a number of presentations of the disease and clinical
signs during the acute phase tend to be non-specific. History and haematology
provide essential guidance.
- Dog has visited endemic area and been exposed to
- Depression, lethargy, stiffness/lameness.
- Anorexia, weight loss, vomiting
- Increased bleeding tendency.
- Ocular disease or blindness.
- Seizures and other neurological signs.
Clinical signs of Canine monocytic ehrlichiosis
- Sudden onset.
- Fluctuating temperature.
- Splenomegaly and
- Limb and scrotal oedema.
- Respiratory signs.
- Petechiae and ecchymoses of the skin and mucous
membranes. Many dogs appear to recover from the acute phase without
treatment and pass into the subclinical phase.
- Ventral oedema.
- Petechial and ecchymotic haemorrhages on hairless
skin or mucous membranes and prolonged bleeding time on
- Hypotension and shock secondary to blood loss.
- Neurological signs, eg signs of
meningoencephalitis (arched back, severe neck and back pain), paraparesis
or tetraparesis, ataxia, hyperaesthesia and convulsions can occur during
the acute or chronic phases.
- Ocular changes, eg conjunctivitis, corneal oedema,
anterior uveitis, hypaema, subretinal haemorrhage, retinal detachment and
- Skin lesions, eg alopecia and crusting.
Haematological changes in canine monocytic
ehrlichiosis include thrombocytopaenia (consistently seen in all stages),
non-regenerative anaemia and leukopenia with severe pancytopaenia developing in
the chronic form. A hypergammaglobulinaemia is seen in all phases although it
is somewhat lower during the pancytopaenia phase. Definitive diagnosis of E.
canis infection is obtained by demonstration of the organism in mononuclear
cells in Giemsa-stained peripheral blood smears or smears from the buffy-coat
layer of untreated animals in the acute phase. The organisms can be seen in
small groups or tightly packed clusters, known as morulae, up to 4 um in
diameter in the vacuoles in the cytoplasm of these cells. The overnight
incubation of buffy-coat and plasma in culture vessels containing flying
coverslips greatly enhances the detection rate of infected mononuclear cells.
However, demonstration of the organism in stained smears is often not possible,
even in the acute phase. Cell culture reisolation of the parasite is the most
sensitive and definitive for early diagnosis – but, due to the length of time
required to obtain a result, it is really only suitable for research purposes.
Serological tests are useful as demonstration of the organism in blood smears
is difficult. Needle aspirates of spleen, lymph nodes and bone marrow should be
checked for the presence of a plasmacytosis in tropical canine pancytopenia.
E. ewingii is seen as morulae in neutrophils and
eosinophils, with E. platys detected as basophilic inclusions in platelets. v
The treatment of choice for canine monocytic ehrlichiosis is doxycycline (10-20
mg/kg/day for a minimum of 3 weeks), on its own or preferably along with
Imidocarb diproprionate (5 mg/kg IM or SC in a single dose repeated after 14
days). The combination is believed to be more effective in preventing the
development of chronic infection and is particularly useful where mixed
infections with Babesia canis are suspected.
Tetracyclines (22-25 mg/kg TID for at least 3 weeks)
could be given as an alternative to doxycycline, except in uraemic cases when
doxycycline is preferred. Chloramphenicol (50 mg/kg PO or IV TID for 14 days)
can be used instead of tetracyclines when discolouration of tooth enamel is a
Supportive therapy including fluid therapy, blood
transfusion and vitamin supplementation may also be required. Glucocorticoids (prednisolone
1-2 mg/kg BID) should be considered until immune-mediated thrombocytopenia and
anaemia resolve. However, the use of immunosuppressive drugs in dogs with
rickettsial disease should be undertaken with caution, especially as these
animals could also be infected with other tick-borne infections.
The prognosis is good for animals that undergo
appropriate treatment during the acute phase. Chronic infections occur in those
that don’t receive proper treatment, eg treated for too short a time period,
and this can lead to the development of tropical canine pancytopenia, which is
refractory to treatment. Recovered animals are usually immune to further
infection but they become carriers and may experience relapses when stressed.
Control can be achieved by the use of acaricides,
including acaricide impregnated collars Prophylactic treatment, using low doses
of tetracyclines, 6.6 mg/kg orally, should be considered for dogs on relatively
short visits to endemic areas or during periods of maximum tick activity.
Further sources: 1. Lobetti R G (1998) Canine
babesiosis. Comp Cont Educ Pract Vet 20, 418-431.
2. Harrus S & Hylton B (1997) Canine monocytic ehrlichiosis – an update.
Comp Cont Educ Pract Vet 19, 431-444.
3. Waner T, Keysary A, Bark H, Sharabani E & Harrus S (2000) Canine
Monocytic Ehrlichiosis – an overview. Israeli J Vet Med 54, 103–107.
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