The external ear canal of goats and other animals as a mycoplasma habitat

Abstract

In an experimental study Mycoplasma capricolum or M. mycoides subsp. mycoides (large colony type) was cultured from the external ear canal of ear mite-free goats, sheep and a pig and isolated from 19 of 20 animals at necropsy whenever a state of mycoplasmal septicemia existed. In M. putrefaciens infected goats, the mycoplasma could not be recovered at necropsy from the ear canal 7–10 days following a state of septicemia. In a field study, M. mycoides subsp. mycoides was culturable from the external ear canal of a clinically normal dairy goat herd with a prior history of infection, but nares and milk did not yield the organism. Cultures of the external ear canal of a small herd of immature and mature Holstein cows without history of mycoplasmal infection, however, resulted in isolation of M. bovoculi from the external ear canal, but no mycoplasma isolations were made from the nares or milk. The significance of ear mites in the external ear canal and their role in mycoplasmal transfer between animals is currently unknown. Mycoplasmemia explains the seeding of the ear canal by bloodborne mycoplasma, but is an unlikely cause for the finding of up to five Mycoplasma sp. from an ear swab culture. For the moment, the precise explanation for the seeding of mycoplasma in the ear canal must await documentation, although a likely reason appears to be the seeding of the canal by mites as they transfer from goat to goat, which apparently occurs with ease.