Canine distemper is a systemic viral disease characterized by immunosuppression followed by secondary infections. Apoptosis is observed in several immunosuppressive diseases and its occurrence on canine distemper in vivo has not been published. In this study, the occurrence of apoptosis was determined in lymphoid tissues of thirteen naturally infected dogs and nine experimentally inoculated puppies. Healthy dogs were used as negative controls. Samples of lymph nodes, thymus, spleen and brain were collected for histopathological purposes. Sections, 5 microm thick, of retropharingeal lymph nodes were stained by HE, Shorr, Methyl Green-Pyronin and TUNEL reaction. Shorr stained sections were further evaluated by morphometry. Canine distemper virus nucleoprotein was detected by immunohistochemistry. Retropharingeal lymph nodes of naturally and experimentally infected dogs had more apoptotic cells per field than controls. In addition, DNA from thymus of infected dogs were more fragmented than controls. Therefore, apoptosis is increased in lymphoid depletion induced by canine distemper virus and consequently play a role in the immunosuppression seen in this disease.

O vírus da leucemia felina (FeLV) e o vírus da peritonite infecciosa felina (FIPV) têm sido descritos em animais selvagens de todo o mundo e são causadores de enfermidades imunodepressoras que podem ser prejudicais à sobrevivência desses animais. O trabalho teve por objetivo relatar a identificação de FeLV e FIPV em felídeos selvagens de cativeiro e de vida livre da região do pantanal matogrossense. Um felídeo selvagem de vida livre (Felis pardalis) e 16 felídeos selvagens de cativeiro (Felis yagouarundi, F. colocolo, F. weindii, F. concolor, Panthera onca) foram avaliados quanto à presença de FeLV e FIPV através das técnicas de imunofluorescência indireta e direta, respectivamente. Dos animais avaliados, 11 foram positivos para FeLV e 12 foram positivos para FIPV, sendo que 9 dos animais eram positivos para um ou ambos vírus, 2 só para FeLV, 3 só para FIPV e 2 negativos. Os resultados sugerem que FeLV e FIPV podem estar disseminados pelos felídeos selvagens e que a exposição desses animais a importantes agentes patogênicos oriundos de animais domésticos, representa, associada a degradação do habitat natural, um risco à preservação da vida selvagem e à saúde humana.