Clinical and laboratory observations in 91 dogs infected with Dirofilaria immitis in northern Greece

The medical records of 91 dogs with heartworm (Dirofilaria immitis) infecti on were reviewed, and diagnoses were established by using parasitological a nd immunological methods. Twenty-one animals were asymptomatic (stage I), 5 7 had mild to moderate clinical signs (stage II), and 13 had the severe for m of the disease including right congestive heart failure and the caval syn drome (stage III). Thoracic radiography revealed right ventricular enlargem ent in 38 of the dogs, pulmonary vascular enlargement in 43, and parenchyma l lesions in 27. Only the cardiac and vascular changes were correlated posi tively with the clinical stages. D immitis microfilaraemia was detected in 75 of 85 dogs. Occult infection occurred only in eight stage II and two sta ge III dogs. Thirty-two of the dogs were treated with thiacetarsamide and 3 9 were treated with melarsomine, and no differences were found in terms of drug efficacy or complication rate; nine stage II dogs suffered pulmonary t hromboembolism and one suffered acute liver disease and there were six fata lities. The 50 treated dogs in stages II and III which were followed up for six months all recovered completely. The performance of 38 of 61 working d ogs was completely restored, and the performance of another four was partia lly restored.