Thirty-five dogs infested with Dirofilaria immitis were euthanized with pentobarbital and MgSO4 and necropsied for the study of the pathological changes of pulmonary arteries. AII dogs showed thickened rugose intimal projections on the main pulmonary artery. Verrucous to typical villus-like intimal proliferations were found in the smaller pulmonary arteries. Nine dogs presented with thrombus in the lobar pulmonary arteries. Histopathological examination of the thrombosed pulmonary arteries revealed subendothelial edema and inflammation in the tunica intima and adventitia and sections of dead heartworms in the core of thrombi. Clinical findings were compared between dogs with and without thrombosis. In the numbers of infested adult worms, dogs with thrombosis (mean=11.5, sd=7.17, n=8) had statistically significant (P < 0.05) more worms than did dogs without thrombosis (mean=6.8, sd=5.09, n=26). Regarding the gender, dogs without thrombosis showed no differences between the male (12/26) and female (14/26) dogs, but the male (6/9) were more susceptible than female (3/9) in dogs with thrombosis. As for the age, there was no difference between dogs with (mean=5.1, sd=2.57, n=9) and without (mean=5.2, sd=2.44, n=26) thrombosis.
Thirty-five dogs infested with Dirofilaria immitis were euthanized with pentobarbital and MgSO4 and necropsied for the study of the pathological changes of pulmonary arteries. AII dogs showed thickened rugose intimal projections on the main pulmonary artery. Verrucous to typical villus-like intimal proliferations were found in the smaller pulmonary arteries. Nine dogs presented with thrombus in the lobar pulmonary arteries. Histopathological examination of the thrombosed pulmonary arteries revealed subendothelial edema and inflammation in the tunica intima and adventitia and sections of dead heartworms in the core of thrombi. Clinical findings were compared between dogs with and without thrombosis. In the numbers of infested adult worms, dogs with thrombosis (mean=11.5, sd=7.17, n=8) had statistically significant (P < 0.05) more worms than did dogs without thrombosis (mean=6.8, sd=5.09, n=26). Regarding the gender, dogs without thrombosis showed no differences between the male (12/26) and female (14/26) dogs, but the male (6/9) were more susceptible than female (3/9) in dogs with thrombosis. As for the age, there was no difference between dogs with (mean=5.1, sd=2.57, n=9) and without (mean=5.2, sd=2.44, n=26) thrombosis.