Cutaneous lesions associated with dual infection caused by canine distemper virus and orthopoxvirus in a domestic cat.

Background: Within the context of an increased epidemiological pressure caused by canine distemper virus (CDV) in Switzerland together with a potential re-emergence of endemic pathogens such as orthopoxviruses (OPXV), dual infections are possible among susceptible species.
Objective: To describe a case of concurrent CDV and OPXV infection in a cat.
Animal: A 5-year-old, neutered male cat was presented with erythema, crusts and ulcerations around the left eye. High-grade pruritus and a severe conjunctivitis were also present.
Methods: Formalin-fixed skin biopsy samples were obtained from lesional skin. Histopathology, CDV immunohistochemistry and CDV and OPXV RT-PCR were performed.
Results: Histopathological examination showed severe epidermal necrosis extending to the follicular walls and a dermal infiltration, predominantly eosinophilic. Intranuclear and intracytoplasmic eosinophilic inclusion bodies were visible in the wall of affected hair follicles, with occasional formation of syncytia. The RT-PCR revealed the contextual presence of both CDV and OPXV. Scattered cells stained positive for CDV by immunohistochemistry.
Conclusion and Discussion: Dual infections with CDV and OPXV, although rare, may occur and represent additional differential diagnoses for ulcerative skin lesions in cats.
(© 2013 ESVD and ACVD.)