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Name
Ehrlichiosis, Canine
Short Description
Ehrlichiosis, Ehrlichia
Affected Animals: Dogs, cats, and in rare instances, humans. German shepherds and
Doberman pinschers tend to be affected more severely by the disease.
Overview:
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 subclinical 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: 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 subclinical 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.
Symptoms: Symptoms of the acute stage of disease include a
fever, lesions within the mucous membrane, bleeding disorders, and
inflammation of the blood vessels. The subclinical phase has no
outward signs of disease. Signs of the chronic stage of the disease
can include pale gums due to anemia, inflammation of the blood
vessels, swollen lymph nodes, difficulty breathing, coughing, kidney
symptoms such as increased urination and increased drinking,
lameness, eye disorders, and neurological disease.
Description:
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,
subclinical, 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 subclinical 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.
Diagnosis: 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 blood
cell.
Prognosis: 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.
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.
Treatment: 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 threatening.
Prevention: 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.
