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December 2021

Animal: Cat, British shorthair, 4.5 years old, neutered female

Organ: Heart

History: Owner noticed bloody urine and diarrhea. In the clinic the cat displayed severe weakness, bilateral pleural effusion (transudate with 22g/L protein), neutropenia and thrombocytopenia. The Rivalta test was negative. Death due to sudden cardiac arrest.

Main macroscopical main findings: Severe pleural abdominal effusion, subcutaneous and alveolar edema, multifocal myocardial petechial hemorrhages.

Main histopathological findings (HE stain): The tunica intima of the small arteries and arterioles of the heart, liver, brain, spleen, intestine, and kidney revealed a severe endothelial activation and proliferation, which occasionally led to vascular occlusion and thrombosis. The heart displayed additionally multiple acute hemorrhages, edema, and degenerated and necrotic cardiomyocytes.

Diagnosis: Severe, multifocal endothelial proliferation with obstruction of vascular lumen

Comment: The histological findings described above are compatible with feline systemic reactive angioendotheliomatosis (Fuji et al, 2005). This multisystemic intravascular proliferative disorder occurs rarely in cats and is often fatal. The heart is consistently affected and most of the affected animals display signs of cardiac dysfunction.


Fuji RN, Patton KM, Steinbach TJ, Schulman FY, Bradley GA, Brown TT, Wilson EA, Summers BA. Feline systemic reactive angioendotheliomatosis: eight cases and literature review. Vet Pathol. 2005; 42(5): 608-617.

Case analysis performed by Inês Berenguer Veiga and Irene Zühlke, Institute of Animal Pathology, VETSUISSE Bern, Switzerland

Picture taken by Inês Berenguer Veiga, Institute of Animal Pathology, VETSUISSE Bern, Switzerland