Ava Frick

Ehrlichia is transmitted by ticks. The carrier tick for dogs (brown dog tick) rarely bites people. The main vector for humans is yet another tick species. Canine infection probably occurs when salivary secretions from the tick contaminate the attachment site during the ingestion of a blood meal. An adult tick is capable of transmitting E. Canis for at least 155 days following detachment from the host. Another tick can obtain the E. Canis only if engorgement (a blood meal) occurs during the acute (early) phase of the disease in dogs.
Once inside the body, Ehrlichia seeks out cells (monocytes, neutrophils, or platelets) of the vascular system upon which to infect. After an 8 to 20 day incubation period, the dog begins a 2 to 4 week acute phase. A sub-clinical phase commences 6 to 9 weeks after onset. Many dogs with a functional immune system will be able to combat the disease by this time. Those unable to mount an effective immune response will become chronically infected. Symptoms include: fever, weight loss, depression, enlarged lymph nodes, anemia, and alterations in blood values. The disease may appear as a joint or muscle illness, respiratory infection, neurological disease, or hemorrhaging.