Natural Occurring Muscular Sarcocysts in Urban Domestic Cats (Felis catus)WithoutSarcocystis-Associated Disease

Purpose Despite of classically acting as definitive hosts of differentSarcocystisspecies, domestic cats have been pointed out as possible intermediate hosts ofS. neuronaandS. felis. Nonetheless, details concerning natural sarcocyst development in cats withoutSarcocystis-associated disease are scarce. This study aimed to characterize the natural occurrence of muscular sarcocysts in a random group of cats submitted for necropsy. Methods One hundred cats necropsied at a Veterinary Pathology Service were included. Nine different muscular tissues from each cat were sampled for histological analysis and Polymerase Chain Reaction (PCR) using multispecies primers forSarcocystis neurona,Neospora caninumandToxoplasma gondii.PCR-positive cases were sequenced for genus and species identification. Epidemiologic data was also analyzed. Results Tissue sarcocysts were identified in hematoxylin and eosin-stained slides from five cats, andS. neuronawas the only confirmed species. Multifocal sarcocysts affecting two or more muscles were common among positive cats (4/5). Sarcocysts were identified within vastus lateralis (3/5), intercostal (3/5), subscapular (2/5) and diaphragm (2/5) sections. These cysts were always incidental necropsy findings. All sarcocyst-positive cats were from urban areas, among which two were feral and three were pets. Outdoor access was consistently reported. Two cats were positive for retrovirosis, and treatments with potentially immunosuppressive drugs were never stated. Conclusions This study describes the natural occurrence ofS. neuronamuscular sarcocysts in a random group of cats withoutSarcocystis-associated disease. These findings reinforce the participation of feral and pet cats from urban areas as natural intermediate hosts ofS. neurona.

Automated summary

This study aimed to characterize the natural occurrence of muscular sarcocysts in a random group of cats without Sarcocystis-associated disease. The study found sarcocysts in five out of 100 cats necropsied, with S. neurona being the only confirmed species. These findings suggest that feral and pet cats from urban areas may serve as natural intermediate hosts of S. neurona.