Canine ehrlichiosis: relapse and prevention

Canine ehrlichiosis is a disease of concern, which can be fatal if left untreated. Canine ehrlichiosis can be caused by different infectious agents, including Ehrlichia canis, Ehrlichia ewingii and Ehrlichia chaffeensis. E. canis is primarily transmitted by Rhipicephalus sanguineus (brown dog tick), while E. ewingii and E. chaffeensis are transmitted by Amblyomma americanum, Haemaphysalis longicornis, Haemaphysalis yeni and Dermacentor variabilis. Ehrlichiosis is one of the most important infectious diseases in some geographic areas, such as the Mediterranean region, the Middle East and Africa, where the disease is endemic beacuse of the presence of its tick vectors. E. canis is an obligate Gram negative intra-cellular bacterium that affects haematopoietic cells. Clinical signs include fever, lethargy, bleeding disorders, inappetence, weight loss and lymphadenomegaly. While corneal opacity is not a specific clinical sign, most affected patients present with uveitis and a lower percentage develop corneal ulcers. This article uses a confirmed case of ehrlichiosis in a dog that was presented to a veterinary hospital to discuss the clinical signs, diagnosis, treatment and recrudescence in the course of the disease management. The dog was presented with the following clinical signs: pyrexia, lethargy, pale mucous membrane and mild corneal opacity. He was diagnosed with ehrlichiosis and was treated with doxycycline, experiencing two relapses in 5 months. The dog recovered after a third course of doxycycline. However, because it may be difficult to completely eliminate E. canis from a previously infected animal, or prevent the relapse, this case further reports the causes of E. canis relapse and the preventive measures necessary to reduce the incidence of relapse. The measures as reported include complete antibiotic therapy at recommended dose, boosting the subject's immunity, tick control measures and a periodic screening of E. canis survivors.