Increased incidence of bovine papular stomatitis in neonatal calves.

A high incidence of bovine papular stomatitis (BPS) occurred in neonatal calves following neonatal thymectomy and antilymphocyte globulin treatment, sham thymectomy, treatment with normal horse globulin and in untreated calves. The source of BPS virus was not identified but was suspected to be latent in the calves and activated by thymectomy although no experimental evidence directly supported this conclusion. The potential for activation of a latent BPS infection was indicated by an apparent relationship between the stress of surgery or foreign protein inoculation and the severity of lesions. Subsequent bovine viral diarrhea virus infection did not result in recrudescence.