AMERICAN TRYPANOSOMIASIS

(Canine CHAGAS DISEASE)

Trypanosomiasis in dogs is caused by the protozoan T. cruzi. A small number of cases have been reported, principally in the southwestern United States, Texas, Argentina, Chile and California.

Raccoons, opossums, armadillos, rats, cats, and dogs serve as the principal reservoirs of T. cruzi.

Dogs (and humans) acquire the disease from a family of insects called kissing bugs. Kissing bugs come out of cracks at night and bite the face of sleepers. Infection occurs through contamination of the bug bites by the insects’ feces. It is also very likely that most dogs become infected by eating infected vectors, causing the release of the organisms into the mouth of the host.

Parasitemia develops after 3-5 days of infections. Signs include fever, weakness, enlargement of the lymph nodes and spleen, and inflammation of the spinal cord and brain. Trypanosomiasis attacks the heart muscle, causing myocarditis with heart arrhythmias. This can lead to collapse and death of the animal. Another complication of myocarditis is congestive heart failure one to three years later. More severe disease often develops in animals less than 6 months of age; prognosis is worse in animals diagnosed at a younger age.

The diagnosis is made by identifying the protozoan in blood smears. Serology tests also are available. An evaluation of the heart via electrocardiogram (ECG) may reveal a number of conduction abnormalities.

Treatment:

Benznidazole is the drug of choice for treating T. cruzi in dogs, d0sage should be 5-10 mg/kg PO every 24 hours for 2 months. Vomiting is the main side effect of this drug. Symptomatic treatment can also be considered for cardiac signs.

Because this often fatal disease can be transmitted to humans through intermediate hosts, euthanizing the animal is recommended. It is essential to take the utmost precautions when handling infected animals, as well as their blood and discharges.