What is canine ehrlichiosis?
Ehrlichiosis is an infectious
disease of dogs. It first gained attention as a significant disease
when military dogs returning from Vietnam during the 1970’s were
found to be infected. The disease seems to be particularly severe
in German shepherds and Doberman pinchers.
The organism responsible for this
disease is a rickettsial organism. Rickettsiae are similar to
bacteria. Ehrlichia canis is the most common rickettsial
species involved in ehrlichiosis in dogs, but occasionally, other
strains of the organism will be found, i.e., Ehrlichia platys.
Because of its origin in military dogs in Vietnam, it has also been
called “tracker dog disease” and “tropical canine pancytopenia.”
How does a dog get infected with
Ehrlichiosis is transmitted to dogs
through the bite of infected ticks; the brown dog tick,
Rhipicephalus sanguineus, is the main reservoir of the organism
What are the signs of Ehrlichiosis?
Signs of Ehrlichiosis can be divided
into three stages: acute (early disease), subclinical (no outward
signs of disease), and chronic (long-standing infection). In areas
where Ehrlichiosis is common, many dogs are seen during the acute
phase. Infected dogs may have fever, swollen lymph nodes,
respiratory distress, weight loss, bleeding disorders, and,
occasionally, neurological disturbances. This stage may last two to
The subclinical phase represents the
stage of infection in which the organism is present but not causing
any sign of disease. Sometimes a dog will pass through the acute
phase without its owner being aware of the infection. These dogs
may become subclinical and develop laboratory changes yet have no
apparent signs of illness. During this stage, the dog may eliminate
the organism, or it may progress to the next stage.
Clinical ehrlichiosis occurs because
the immune system is not effective in eliminating or controlling the
organism. Dogs are likely to develop a host of problems: anemia,
thrombocytopenia (decreased platelets, the blood clotting cells),
bleeding episodes, lameness, eye problems (including hemorrhage into
the eyes), neurological problems, and swollen limbs. If the bone
marrow (site of blood cell production) fails, the dog becomes unable
to manufacture any of the blood cells necessary to sustain life (red
blood cells, white blood cells, and platelets).
is Ehrlichiosis diagnosed?
It may be difficult to diagnose
infected dogs during the very early stages of infection. The immune
system usually takes two to three weeks to respond to the presence
of the organism and develop antibodies. Since the presence of
antibodies to Ehrlichia canis is the basis of the most common
diagnostic test, such dogs may be infected yet test negative.
Testing performed a few weeks later will reveal the presence of
antibodies and make confirmation of the diagnosis possible.
Rarely, the organism itself may be
seen in blood smears or in aspirates of cells from lymph nodes,
spleen, and lungs. This is a very uncommon finding. Therefore,
detection of antibodies, coupled with appropriate clinical signs, is
the primary diagnostic criteria.
How is Ehrlichiosis treated?
Dogs experiencing severe anemia or
bleeding problems may require a blood transfusion. However, this
does nothing to treat the underlying disease.
Certain antibiotics are quite
effective, but a long course of treatment may be needed. Your
veterinarian will discuss treatment options with you.
Can anything be done to prevent
Ridding the dog’s environment of
ticks is the most effective means of prevention. When this is not
possible, low doses of one of the tetracyclines can be given during
Can I get Ehrlichiosis from my dog?
No. However, humans can get canine ehrlichiosis. The disease is
only transmitted to humans through the bites of ticks. Thus,
although the disease is not transmitted directly from dogs to
humans, infected dogs serve as sentinels to indicate the presence of
infected ticks in the area and may be a source of the organism for
infections in humans or other dogs.
This client information sheet is
based on material written by Ernest E. Ward Jr., DVM
2002 Lifelearn Inc. Used with permission under license.
June 29, 2004.