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Canine Ehrlichiosis


What is it?
Canine Ehrlichiosis, also called Tick Fever, is a tick-transmitted disease affecting dogs.  The brown dog tick carries the organism causing the disease and transmits the disease while feeding on the dog’s blood. Ehrlichiosis has two phases – the acute and chronic phases.  The acute phase occurs one to three weeks after exposure to the tick. The chronic phase may occur several months after the acute phase. In both phases, there is destruction and decreased production of all blood cells (red blood cells, white blood cells and platelets). The Companion Animal Parasite Council reported over 11,000 cases of Canine Ehrichiosis in Arizona in 2009. For information on the geographic distribution of tick-borne disease in Arizona and throughout the United States, visit

Clinical signs of the acute phase of the disease are non-specific and therefore difficult to diagnose.  These may include listlessness, swollen lymph nodes, anorexia, fever, neurological signs and discharges from the eyes and nose.  The signs of the chronic phase of the disease may include those mentioned above plus nosebleeds or other abnormal bleeding, weight loss and eye problems.   With destruction and decreased production to the blood cells there may be anemia, decreased resistance to disease and infections.

Accurate diagnosis depends on blood testing. We can perform a special titer test to diagnose if the dog has the acute or chronic form of the disease.  Or we can perform a simple positive/negative test; with this test we do not know the animal’s ehrlichia titer, so we are unsure if the animal is acutely or chronically affected. We also frequently like to perform a complete blood count to measure the number of red blood cells, white blood cells and platelets in the dog’s blood.  A history of prior tick infestation is a helpful clue.  However, many owners are unaware that a tick ever bit their dog. And, it only takes one tick to transmit the organism that causes the disease.

The acute phase of the disease usually responds well to treatment.  The chronic phase is difficult to treat and may require several months of therapy.  Treatment for both phases involves specific antibiotics.  Some dogs may require other supportive therapies, such as blood transfusions, anti-vomiting drugs and painkillers. We like to monitor our patients with reexaminations and perhaps repeat blood testing every two to four weeks. Unfortunately, some chronically affected dogs require life-long therapy, and the disease can occasionally be fatal.

The best prevention is to keep your dog free of ticks.  At Brown Road Animal Clinic we recommend the use of Frontline Plus on a monthly basis. Frontline Plus will kill all ticks on the dog, usually within 48 hours.  A new product may be recommended for some dogs. Introduced in July 2011, Certifect is a different type of monthly tick treatment that will kill all stages of ticks in 18 hours. Certifect is NOT for use on cats. Dog owners must also spray the house and yard for ticks.  Remember, the brown dog tick is the most widely distributed tick in the United States.  It seldom attacks man as it feeds on dog’s blood.  It Infests any place the dog lives, including dog kennels, runs, backyards and even the home.  Ticks may hide in baseboards, curtains, carpets and windows. Severely infected premises may require a pest control operator to successfully control the problem and/or rid the problem.