RESUMO
We did a descriptive study to determine whether the presence in the external ear canal of the Raillietia caprae mites and Mycoplasmas were associated. For that we sampled 360 goats slaughtered at abattoirs in the summer to identify those infested with the mite. We found only 20 infested, so used all of those plus another 47 uninfested goats selected systematically from the population negative for the isolation of Mycoplasmas. These goats came from the regions of Queretaro, Guanajuato, Sinaloa and Estado de México. Sterile swabs were taken from each ear canal of the carcass after removal of the pinna for microscopic observation of the mites and for the isolation of Mycoplasmas in both study groups. The swab samples were inoculated in Friis media for the isolation of Mycoplasmas; then, the isolates were biochemically characterized and identified serologically. We recovered isolates from the earwax of only nine of the 47 control goats, but from the earwax of 11 of the 20 infested goats; another four infested goats had Mycoplasma isolated from the mites but not from the earwax. Mycoplasma cottewii and Mycoplasma yeatsii were the only Mycoplasmas isolated from the uninfested goats, and also were the predominant (29 of 34) isolates from the infested goats and/or from the mites.