Ehrlichiosis in Dogs

Overview of Canine Ehrlichiosis

Ehrlichiosis is a tick-born disease of dogs characterized by fever, lethargy, lameness and/or bleeding tendencies. It is caused by one of several rickettsial organisms that belong to the genus, Ehrlichia. Ehrlichia canis (E. canis) is the primary causative agent in dogs.

Rickettsia are small microscopic organisms that are different from both bacteria and viruses. They enter various cells of the body and behave as tiny parasites, eventually killing the cell. Ehrlichiosis occurs worldwide, and it achieved prominence during the Vietnam War, when a large proportion of military dogs contracted the disease.

The disease is spread predominantly by the brown dog tick in the United States. Ticks are seen on the affected dog less than half the time, however. Infrequently, ehrlichiosis can be caused by the transfusion of infected blood. It occurs much more commonly in the dog than in the cat. It can be seen in any age dog, although it is seen most commonly in middle-aged animals. Purebred dogs, especially German shepherd dogs, appear to be more susceptible than crossbred dogs.

The impact on the affected individual can vary from very mild clinical signs to severe, life threatening disease. Several different stages of the disease are possible. Subclinical, asymptomatic infection may occur and may persist for months or years. Acute clinical signs may develop in some dogs and resolve spontaneously or with treatment. Acute infections may also develop into chronic infections that produce more severe clinical signs.

What to Watch For

Symptoms of ehrlichiosis in dogs may include:

Diagnosis of Ehrlichia Infection in Dogs

Treatment of Ehrlichia Infection in Dogs

Depending on the severity of clinical signs, treatment options may include outpatient care or may necessitate hospitalization. Antibiotic therapy is the mainstay of treatment for ehrlichiosis. In severely ill patients, intravenous fluid therapy, blood transfusions, and other forms of intensive support may be indicated.

The most common antibiotics used to treat ehrlichiosis belong to the tetracycline family of drugs. They include doxycycline, tetracycline, oxytetracycline, and minocycline. These antibiotics have the greatest efficacy against Ehrlichia, and the fewest side effects.

Home Care and Prevention

At home, be sure to administer all medication exactly as prescribed and return for follow-up testing as directed by your veterinarian. Most antibiotics are given for at least two to three weeks for this disease. Prognosis with acute disease is excellent if caught early. Dogs in the acute phase of the disease often show improvement within 72 hours of starting the antibiotics. The prognosis with chronic cases varies, and dogs with chronic disease may require prolonged treatment.

Be aware that although uncommon, ehrlichiosis has been reported in people. It is felt that human transmission probably occurs through the bite of a tick, and is not caught from an infected dog.

Prevention is possible by decreasing exposure of the dog to ticks. Tick infestation can be prevented by spot-on medications that are applied to the skin, with sprays, collars, and dips. Avoid tick-infested areas, and remove ticks as soon as possible, as they must be attached for a minimum of 24 to 48 hours in order to transmit the disease.

In-depth Information on Ehrlichiosis in Dogs

Ehrlichiosis is a tick-borne disease caused by one of several organisms. It is most often transmitted through the bite of the brown dog tick. Although seen more often in the southeastern part of the United States, it has been reported throughout the country. It can occur in any age or breed of dog, and is most common in the German shepherd dog.

Different phases of the disease are associated with different clinical signs. The acute (immediate) phase develops within 8 to 20 days after the parasite enters the body. This delay between infection and manifestation of clinical signs is called the incubation period. The acute phase often lasts for two to four weeks. In some dogs, the acute phase resolves spontaneously without the dog showing any clinical signs.

Some dogs go on to develop a subclinical infection that persists for months. The parasite remains in these dogs, but no clinical signs are produced. The disease may also enter a chronic phase, which generally occurs two to three months after infection and can last for months to years. Dogs with chronic disease may show a variety of clinical signs. Ehrlichiosis may be associated with subtle nonspecific signs like lethargy, depression, anorexia and fever, or it can have a major impact on certain blood components, such as the platelets, red blood cells, and white blood cells. Decreased numbers of platelets (thrombocytopenia) are common and may be associated with life-threatening bleeding.

There are several diseases or disorders that appear clinically similar to ehrlichiosis. These include:

Diagnosis In-depth of Ehrlichiosis in Dogs

Certain diagnostic tests are required to make a definitive diagnosis of ehrlichiosis and to exclude other diseases that may cause similar symptoms. A complete history (travel pattern, exposure to ticks), description of clinical signs, and thorough physical examination are all-important to obtaining a tentative diagnosis. In addition, the following tests are recommended to confirm a diagnosis:

Your veterinarian may recommend additional tests to exclude or diagnose concurrent conditions. These tests are not always necessary and are selected on a case-by-case basis. These tests include:

Therapy In-depth of Ehrlichiosis in Dogs

Patients with anemia (low red blood cell count) and/or bleeding from decreased platelet counts are most often hospitalized for supportive care. Animals that are not seriously ill are treated as outpatients, but require close monitoring, especially in the initial stages of therapy. With appropriate therapy, many dogs with acute disease do quite well. In more chronic cases, response to therapy can take longer and sometimes the response is poor. It is very important to follow all recommendations by your veterinarian very closely, and to address any questions or concerns that arise during the treatment protocol immediately.

Follow-up Care for Dogs with Ehrlichiosis

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not rapidly improve. Administer all prescribed medication as directed. Alert your veterinarian if you are experiencing problems treating your pet. Most antibiotics are given for at least two to three weeks for this disease.

If abnormalities are detected initially in the blood count and platelet count, then it is common for these tests to be repeated every two to five days after initiating therapy, until the counts are back to normal. A biochemistry profile is initially repeated every four to 10 days, especially if abnormalities were detected on the original work-up.

Serology may be repeated nine to 12 months after therapy. Most antibody titers peak between 2 and 5 months after infection, and then start to decrease if the parasite is eliminated from the body. A persistently high positive titer may represent reinfection or ineffective therapy, and may indicate the need for a second round of therapy.

Prognosis with acute disease is excellent if caught early. Dogs in the acute phase of the disease often show improvement within 72 hours of starting the antibiotics. The prognosis with chronic cases varies, and dogs with chronic disease may require prolonged treatment.