Computed Tomography Assessment of the Bronchial Lumen-Vertebral Body and Pulmonary Artery-Vertebral Body Relationships in Cats Naturally Infected with Immature Dirofilaria immitis

Abstract

Feline heartworm disease, caused by the parasite Dirofilaria immitis, is a serious condition that often goes undetected in cats. Unlike dogs, which typically develop infections with adult worms in the heart, cats more frequently experience a larval form of the disease known as Heartworm-Associated Respiratory Disease (HARD), which primarily affects the lungs. Because affected cats often show vague signs such as coughing or breathing difficulty, diagnosing can be challenging. In this study, we used advanced imaging with computed tomography (CT) to examine the lungs of naturally infected cats. By comparing CT measurements from infected cats with those from healthy controls, we found that infected cats showed clear widening of the airways (bronchi), even when the pulmonary arteries appeared normal. To ensure reliable comparisons, lung measurements were standardized using the cat's spine as a stable reference point. These findings show that specific CT-based lung measurements can help veterinarians detect early-stage heartworm infection in cats more accurately. This approach may improve diagnosis in areas where the parasite is common and support earlier treatment and prevention, ultimately benefiting feline health and welfare.