Radiographic findings in dogs from an endemic area for heartworm disease in the state of Rio de Janeiro.

Canine heartworm disease causes significant pulmonary abnormalities, even in asymptomatic cases. This study aimed to compare the chest radiographs of cases infected with Dirofilaria immitis with those of heartworm-negative dogs. Fifteen animals treated at a private veterinary clinic in the municipality of Maricá, Rio de Janeiro, underwent chest radiography, regardless of their serological status, for the presence of D. immitis antigen, and none of them used preventive measures. Eight dogs tested positive for the antigens on immunochromatographic tests (8/15, 53.3%). When the radiographs of the two groups of dogs were blindly compared, the increase in the caudal pulmonary arteries showed a strong positive correlation (0.732) with infection using the Spearman correlation test. These results suggest that heartworm infection, even in the absence of clinical signs, elicits caudal lobar pulmonary artery enlargement that can be detected on radiography.