Risk factors and select cardiac characteristics in dogs naturally infected with Trypanosoma cruzi presenting to a teaching hospital in Texas.

ABSTRACT

BACKGROUND: Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, causes sudden death and chronic heart disease with no currently approved treatment. OBJECTIVE: To report epidemiologic and select cardiac characteristics associated with T. cruzi infection in dogs presenting to a teaching hospital in Texas. ANIMALS Three hundred seventy-five client-owned dogs. METHODS: A retrospective search of medical records identified dogs tested for T. cruzi antibodies or with histologic T. cruzi parasites. Data retrieved included signalment, location of residence, reported reason for testing, cardiac troponin I (cTnI) concentration, and ECG abnormalities. RESULTS: Trypanosoma cruzi-infected dogs (N = 63, 16.8%) were significantly younger than negative dogs (N = 312) (mean, 5.9 ± 3.8 versus 7.4 ± 4.0 years; P = .007) with no difference by sex or breed. Ninety-one breeds were tested; the highest percent infected were non-sporting (10/35; 29%) and toy breed (10/42; 24%) groups. The odds of infection were 13 times greater among dogs with an infected housemate or littermate (95% confidence interval [CI], 3.94-50.45; P < .001). Infected dogs were more likely to have ventricular arrhythmias (odds ratio [OR], 2.19; 95% CI, 1.15-4.33, P = .02), combinations of ECG abnormalities (OR, 2.91; 95% CI, 1.37-5.99; P = .004), and cTnI >0.129 ng/mL (ADVIA; OR, 10.71; 95% CI, 1.60-212.21; P = .035). CONCLUSIONS AND CLINICAL IMPORTANCE Dogs infected with T. cruzi were identified in Texas in many breed groups including breeds affected by well-described heart diseases that mimic Chagas disease suggesting a need for increased awareness, including knowledge of when to consider testing.