The Cardiopulmonary Dirofilariosis is a disease caused by Dirofilaria inmitis which mainly affects dogs. The major histopathological findings occurring in lungs and heart, but there are frecuent microscopic lesions in other organs such as kidneys and liver. The adult parasite is located at the right ventricle and pulmonary artery. It is transmitted by vectors, mainly blood-sucking mosquitoes. The research was descriptive, retrospective, non-experimental and was developed with samples from 17 cases of canine Dirofilariosis which were presented in the necropsy room of Pathology of Universidad Nacional Experimental Francisco de Miranda. The collected tissues were processed using the technique stained with hematoxylin and eosin following technique of Harry, and then carry out a histopathological study of individual cases dog Dirofilariosis, where alterations were found at lung, heart, liver, kidney and pulmonary artery. The disease was most often found in male dogs which account for 70.58%, of case aged between 5 and 6 years, the majority belonging to the Municipality of Miranda, Falcon State, Venezuela. Histopatological changes were congestion and emphysema with alveolar and interstitial peribronquial neumonitis and pulmonary artery endoarteritis heart congestion, hyalinization of muscle fibers and myocarditis, liver congestion, glycogenic swelling of hepatocytes and inflammation of the liver parenchyma; in kidney; glomerulonephritis and pyelonephritis was observed. Particularly noteworthy was the presence of mononuclear inflammatory cells in all these organs, which determines the migratory systemic pattern of the parasite and microscopic lesions characteristic of this disease. The aim of this study was to determine the histopathological lesions of the dog Dirofilariosis cases at the Pathology Department of the Universidad Nacional Experimental "Francisco de Miranda", years 2003-2008.
