Title:Okkult Dirofilaria immitis szívférgesség kutyában Esetismertetés és irodalmi áttekintés
SUMMARY Background: Occult dirofilariosis caused by Dirofilaria immitis occurs in dogs when no microphilariae can be detected in the peripheral blood, despite the presence of adult heartworms. Objectives: The authors report on an autochthon case of true occult dirofilari osis caused by D. immitis in a dog originated from an endemic region of Hungary. A comprehensive review of the literature of occult dirofilariosis was added to the case report. Materials and methods: No macrocyclic lactone treatment/prevention was applied as to the history of the patient. The diagnosis was based on the clinical symptoms, radiologic alterations of the lungs as well as on the echocardiographic findings. Heartworm disease (HWD) was confirmed by four positive antigen tests of different manufacturers. Results and discussion: The patient was categorized into the severe, third clini cal stage of HWD. Major clinical symptoms included occasional fainting, weakness, frequent coughing, severe dyspnoea, and signs of right-heart failure. Radiographic and echocardiographic alterations were characteristic for advanced HWD. Echo cardiography also revealed secondary pulmonary hypertension and a few adult worms were detected within the right major pulmonary artery. The dog was stabi lized by treating the congestive heart failure for three weeks. Thereafter, complex HWD treatment procedure was applied as to the recommendations of the latest (2014) version of the American Heartworm Society. Remarkable improvement of the clinical symptoms as well as radiographic and echocardiographic alterations were seen after one month following HWD treatment. By six months, the dog nearly completely healed clinically and the antigen tests became negative. True occult dirofilariosis should be considered when no microphilariae are present in the peripheral blood without preceding macrocyclic lactone application and adult heartworms can be detected by antigen tests and/or with echocardiogra phy. This phenomenon can cause a diagnostic challenge and should be especially considered in endemic regions of heartworm disease.