Bronchial lumen-vertebral body and pulmonary artery-vertebral body relationship using Computed Tomography in cats seropositive to Dirofilaria immitis

Abstract

Feline dirofilariosis is primarily distinguished from canine dirofilariosis due to the intense response to Dirofilaria immitis, this produces an intense inflammation in the lungs, which is known as “Heartworm Associated Respiratory Disease” (HARD). This inflammation can affect the bronchial and vascular structure of the lung. Nowadays, Computed Tomography (CT) is increasingly common in veterinarian medicine, as it is beneficial in the identification of feline thorax pathologies. The evaluation of the ratios obtained from the bronchial lumen to the vertebral body (BV) and the pulmonary artery to the vertebral body (AV) are of great importance in the recognition of alterations in the different structures of the lung. The objective of this study was to examine these proportions in cats naturally infected with D. immitis to evaluate the lesions generated by the parasite in this disease. Taking into account information on sex, breed, age and body weight, 38 animals were studied to determine the BV and AV characteristics through CT. This information was separated into two groups based on whether the animals had a diagnosis of HARD (30) or they were healthy animals (8). No significant alterations were observed in the diameter of the arteries of the seropositive cats compared to the seronegative ones, so they did not show signs of pulmonary hypertension. On the other hand, the bronchi were affected, mainly in the right middle lobes and cranial subsegment of the left cranial lobe when comparing between groups. Likewise, it was observed that among the lobes, the caudal lung lobes were more affected. This BV ratio allowed us to determine those cats with bronchiectasis due to respiratory pathologies. The ratio of BV has never been documented previously in naturally infected cats, so this information could be used as a guide for future research. With this, the BV ratio could be useful when bronchial structures are affected in diseases such as HARD or HWD, especially in the presumptive diagnosis of the disease in endemic areas. However, more research should be conducted to support these findings.