A nonhealing ulcerative skin lesion associated with Trichinella nativa infection in a cat.

Trichinella spp. can infect various domestic and wild species, including companion animals. Infection occurs because of the ingestion of raw meat (e.g., infected prey). In experimental studies, cats have been found to be a very susceptible host to infection by Trichinella spp.; naturally occurring feline infections have also been reported. However, clinically apparent disease seems to be a rare manifestation of this infection in cats. The skin biopsy of an 8-year-old, neutered, male, domestic cat revealed an inflammatory granulation tissue that surrounded a well-preserved cyst that contained a Trichinella sp. larva. Distinct seropositive reaction against Trichinella spp. antigens was demonstrated by enzyme-linked immunosorbent assay and Western blot. Immunohistochemistry, by using serum from the infected cat as the source of antibody, showed strong immunostaining of Trichinella spp. larvae. During a 1-year follow-up, a postexcisional local tissue reaction was observed. This manifested as a firm, poorly circumscribed subcutaneous mass adjacent to the eye, which demonstrated clinical features and histopathologic findings indicative of chronic inflammation associated with granulation tissue and fibrodysplasia. Digestion of the muscle biopsy revealed one Trichinella sp. larva, which was identified by multiplex polymerase chain reaction as Trichinella nativa. To the authors' knowledge, this is the first documented case of trichinellosis in a cat with a nonhealing ulcerative skin lesion as the main clinical manifestation of the infection.