Rabies in a vaccinated canine exhibiting generalized demodicosis.

Abstract

Rabies remains enzootic in the striped skunk population of the midwestern USA with intermittent periods of epizooticity. In 1992, Kansas experienced the third epizootic in skunk rabies since 1969. The dramatic increase in skunk rabies produced a “spillover” effect into other animals that occurred statewide and subsequently infected 24 domestic animals (1992 Kansas Rabies surveillance data, KSU Department of Veterinary Diagnostic Investigation). When epizootics of rabies occur, the potential for rabies infection of domestic animals increases, especially in those animals more “at risk,” i.e., unvaccinated, immunocompromised, or immunosuppressed. This report describes the clinical, histopathologic, and polymerase chain reaction (PCR) confirmation of rabies in a previously vaccinated, probably immunosuppressed dog. On December 13, 1990, a 9-month-old purebred husky was vaccinated with a 3-year killed rabies vaccine product. At the same time, the dog was also diagnosed as having a generalized infection of Demodex cunis. The dog was initially treated with Mitaban, but treatment was not continued after 1 bottle had been dispensed to the owners. The dog never fully recovered from generalized demodicosis. On January 25, 1992, the dog attacked and killed a striped skunk that was confirmed to be rabid at the Department of Veterinary Diagnostic Investigation, College of Veterinary Medicine, Kansas State University. The dog had not received a booster vaccination for rabies. On February 24, 1992, the dog presented with excessive drooling and staggering. The dog was euthanized and submitted for rabies examination. Saliva samples collected from the dog at the time of submission were subjected to reverse transcription PCR using primers specific for the leader sequence of rabies virus nucleoprotein. Fresh brain tissue was tested for presence of rabies antigen using a direct fluorescent antibody test (FAT), and brain tissue fixed in 10% formalin was examined histologically. Brain tissue was also submitted to the Centers for Disease Control (CDC) in Atlanta, Georgia, for monoclonal antibody typing.