Ehrlichia canis is the rickettsial organism responsible for causing the disease known as Ehrlichiosis in dogs. This pathogen has been found in all 48 contiguous United States, but is more prevalent in the south. Brown dog ticks are responsible for spreading the disease to dogs during a blood meal.
Ehrlichia ewingii is similar, but is spread by the Lonestar tick and is found more commonly in the southeast and midwest United States. Dogs with this infection will show lameness, stiffness, and reluctance to move.
The organism lives inside the white blood cells of the dog. It can remain there for months without causing clinical disease symptoms in the dog. Dogs with a healthy immune response will make antibodies against the organism and kill it, resulting in no clinical disease.
When symptoms do occur, they may include fever, lethargy, weight loss, swelling of the legs, enlarged lymph nodes, pale gums, anemia, and seizures. Severe disease can lead to uncontrollable hemorrhage and death.
Testing for Ehrlichiosis includes antibody tests which detect antibodies against the organism in the blood. Antibodies will typically appear seven days after infection. In-office screening tests can have false positive results. Any dog testing positive should have a follow-up PCR test to determine whether Ehrlichia is actually present. If the PCR is negative, no treatment is needed, unless the dog is clearly symptomatic.
Treatment includes the use of doxycycline, an antibiotic, once or twice daily for three to four weeks. Improvement should be seen within 24 to 48 hours. Doxycycline commonly causes nausea and vomiting. Doxycycline should not be given with dairy products, as calcium will bind the drug, rendering it useless.
No vaccines are available for this disease. Keeping ticks off your dog is your best defense. Please do this as naturally as possible. Your dog's healthy immune system can keep this disease from every becoming clinically manifested.