Pulmonary arterial changes in feline dirofilariasis

Area of Science:

• Veterinary Pathology
• Parasitology
• Cardiovascular Science

Background:

• Spontaneous dirofilariasis, caused by the heartworm Dirofilaria immitis, is an emerging concern in feline medicine.
• Clinical presentation in cats can be subtle, making diagnosis challenging.
• Necropsy studies are crucial for understanding the full spectrum of pathological changes.

Purpose of the Study:

• To characterize the pathological findings in cats with naturally occurring heartworm disease.
• To investigate the vascular lesions in the pulmonary arteries and associated cardiac changes.
• To correlate the presence of heartworms with observed pathological alterations.

Main Methods:

• Necropsy of eleven cats with confirmed spontaneous dirofilariasis.
• Gross and histopathological examination of the heart, pulmonary arteries, and liver.
• Evaluation of inflammatory cell infiltration and vascular remodeling.

Main Results:

• Heartworms were found in the right ventricle and pulmonary arteries of all eleven cats.
• Significant pathological changes included intimal thickening, villous endarteritis, and thrombosis in pulmonary arteries.
• Evidence of right-sided heart failure, such as right ventricular dilation and liver congestion, was observed in four cats.

Conclusions:

• Feline dirofilariasis induces severe proliferative and inflammatory vascular lesions in the pulmonary arteries.
• These vascular changes can lead to pulmonary hypertension and right-sided heart failure.
• Pathological findings underscore the significant impact of heartworm infection on feline cardiovascular health.