EHRLICHIOSIS IN DOGS
Canine Ehrlichiosis is a disease of dogs and wild canids and is found worldwide. Ehrlichiosis is a rickettsial disease. Also known as tick fever, it is formerly known as tropical canine pancytopenia.
What causes Ehrlichiosis?
- Multiple strains of Ehrlichia, affecting different species of animals
- Most commonly caused by Ehrlichia canis
How is Ehrlichiosis Transmitted?
- Most commonly transmitted by the Brown Dog Tick and the Lone Star Tick
- A single tick bite can transmit the disease (a tick infestation is not necessary)
- Tick feeds on an infected animal then feeds on another animal thereby transmitting the disease
- Ehrlichia can remain alive in the developing tick for up to 5 months (this means tick can become infected in fall and infect a dog the following spring)
- Because the disease is transmitted by ticks, it can occur wherever Brown Dog and Lone Star Ticks are found
- Almost every state in the US has reported cases
Symptoms of Ehrlichiosis
- Three phases of Ehrlichiosis: acute, subclinical, and chronic
Acute Phase:
- often so subtle the dog appears well
- usually develops 1-3 weeks after the bite of the infected tick
- generally lasts 2-4 weeks
- the disease enters the white blood cells and reproduces inside them
- in addition to the blood, these cells are found in the lymph nodes, spleen, liver, and bone marrow
- platelets are often destroyed as well
- lymph nodes, liver, and spleen are often enlarged
- anemia, fever, depression, lethargy, loss of appetite, shortness of breath, joint pain and stiffness, and bruises often seen
- many dogs will be able to fight off infection. If not, they enter the subclinical phase
- easily treated with no lasting effects
Subclinical Phase:
- animal may appear normal or show only slight anemia
- phase can last for months or years
- during this phase the infection lives in the spleen
- ultimately the dog either recovers or the infection progresses to the chronic phase
- typically successful with up to 3 months treatment
Chronic Phase:
- can be either mild or severe
- weight loss, anemia, neurological signs, bleeding, inflammation of the eye, edema in the hind legs, and fever may be seen
- one or all of the different types of blood cells are decreases
- in some cases arthritis or a kidney disease may develop
- decreased platelet count is most common lab finding in all phases
- typically die without treatment
- treatment lengthy and sometimes complicated
How is Ehrlichiosis Diagnosed?
- Based on typical clinical signs and special blood tests
- Indirect immunofluorescent antibody (IFA)
- ELISA test
- PCR test
How is Ehrlichiosis Treated?
- Doxycycline is used
- Imidocarb dipropionate is sometimes used in conjunction with the antibiotics
- Treatment can be 2 weeks to several months (a complicated Ehrlichia case can take years)
- Some dogs need blood transfusions, IV fluids, and other supportive care
Prevention of Ehrlichiosis
- Tick control (see Elimination of Brown Dog Ticks)