Canine monocytic ehrlichiosis, also known as canine rickettsiosis, canine hemorrhagic fever, tracker dog disease, canine tick typhus, Nairobi bleeding disorder and tropical canine pancytopenia, is a tick-borne parasitic bacteria transmitted by the brown dog tick. Easy to treat in its earlier stages, canine monocytic ehrlichiosis can become fatal if allowed to progress to the chronic stage of infection.
The African Bug
Discovered in Algeria in 1935, canine monocytic ehrlichiosis, or CME, currently exists in Africa, Asia, Europe and every state within the United States. During the Vietnam War, more than 300 military dogs succumbed to the disease. Spread by the saliva of brown dog ticks as the arachnids feed on hosts, CME infects domestic dogs as well as other canids such as wolves, foxes and coyotes. Transfusions with infected blood will also transmit the disease. All dog breeds, sexes and ages are susceptible to infection, which progresses in three stages following incubation. German shepherd dogs demonstrate increased susceptibility of progressing to the chronic stage of infection, which carries a high mortality rate.
Bloated Ticks to Bleeding Dogs
Once the infection has passed from the tick to the dog, it incubates for a period of eight to 20 days. Factors affecting the severity of the disease include the breed of the dog, his immune status, stress level, presence of other parasitic infections, geographic location, the strain of the parasite and whether or not the dog has experienced persistent reinfection of the disease. Most initial symptoms are mild, but in some cases the dog may quickly become critically ill.
Acute Illness Isn't So Cute
Acute infection, the first stage of CME, presents symptoms after the incubation period has passed. This stage may last one to two weeks. Common symptoms include fever, anorexia, lethargy, enlarged lymph nodes and abnormally low blood platelet counts. An affected dog may have an increased tendency to bleed, including bruising or bleeding of the skin and mucous membranes, corneal opacity and subretinal hemorrhaging, which can result in retinal detachment and blindness. He may vomit, exhibit lameness or have discharge from his eyes and nose.
The Disappearing Disease
Following the acute phase, the dog may progress to the subclinical phase. In this stage, many dogs, while still carriers of the disease, appear outwardly healthy. Potentially lasting for weeks to months, or even years, symptoms may include weakness, depression, anorexia, chronic weight loss, fever, swelling of the hind limbs and scrotum, and pale mucous membranes. Accurate diagnosis during this phase can present a challenge to veterinarians.
The chronic or severe phase is the final and most dangerous phase of the disease. In most cases, the disease is fatal once it has progressed to this stage. Symptoms include secondary bacterial infections, pneumonia, kidney failure, arthritis and reproductive disorders.
Exterminating the Bug
Good grooming practices and tick control provide the best prevention. Many dogs who have become infected will naturally eliminate the disease. For dogs requiring treatment, early diagnosis is essential to prevent the disease from progressing to its most dangerous phase. Medications such as tetracycline, oxytetracycline, minocycline and chloramphenicol will successfully eliminate the parasitic bacteria. The most successful courses of treatment last for approximately three weeks. All stages of treatment should be supervised by a veterinarian.
- University of Wisconsin School of Veterinary Medicine: Ehrlichiosis
- American Society for Microbiology/Journal of Clinical Microbiology: Recent Advances in Determining the Pathogenesis of Canine Monocytic Ehrlichiosis
- International Veterinary Information Service: Recent Advances in Canine Infectious Diseases
- Ablestock.com/AbleStock.com/Getty Images