Avaliação e caracterização das alterações do trato respiratório caudal de cães com infecção natural por Dirofilaria immitis (Leidy, 1856) por meio de tomografia computadorizada

Abstract

The main clinical signs of heartworm disease in dogs are characterized by respiratory manifestations which are associated to signs such as dry cough, exercise intolerance, tachypnea, hemoptysis and dyspnea. Although, the radiographic examination of thorax has been used to identify changes in the pulmonary patterns, the Computed Tomography (CT) has been currently considered the method of choice for evaluation of pulmonary parenchyma and lower airways. Therefore, the aim of this study was to assess pulmonary changes in dogs naturally infected by Dirofilaria immitis by using CT. Domiciled dogs (n = 12) living in the Metropolitan Region of Recife were used in this study. All animals positive for D. immitis were physically examined, and analyzed through the microscopic examination of blood samples, serological analysis (D. immitis and Leishmania infantum), electrocardiography and CT. The quantitative assessment of pulmonary radiodensity presented mean value of -628.58 ± 56.60 HU, which was significantly higher than the normal parameter of lung parenchyma of dogs. Moreover, the results revealed the presence of interstitial infiltrate, increase of tortuosity of caudal arteries, increase of bronchial arteries and gap filling of pulmonary artery were present in different degrees, including in the animals that present occult heartworm. Afterwards, a female Dachshund with eight-year-old was treated with Ivermectin and Doxycycline, being monitored twice by CT. The CT examination performed before the treatment showed the presence of D. immitis adults in the pulmonary artery, vascular tortuosity and parenchymal inflammation. After therapy, it was observed an improvement in the clinical status of the animal, which scored negative at serological examination. In addition, it was observed the remission of pulmonary changes and absence of D. immitis adults in blood vessels and heart chambers. In conclusion, the CT may be considered an important tool to detect changes in pulmonary parenchyma of dogs naturally infected by D. immitis, in addition, it allows the diagnosis of occult heartworm.