Vernon C. Bleich, Christine K Johnson, Steven G. Torres, James H. Davis, Jennifer M. Ramsey, Jeffrey T. Villepique, Ben J. Gonzales

Research output: Contribution to journalArticle


The authors captured bighorn sheep (Ovis canadensis) comprising a small population in the San Bernardino Mountains of California and evaluated the degree of infestation by mites of the genus Psoroptes for each individual. The animals were treated with two novel methods: amitraz-impregnated collars and cyfluthrin-impregnated ear tags and recaptured the following year to evaluate the effect of treatment. The authors compared data on degree of infestation for animals recaptured in the posttreatment year, detected no significant interyear differences in infestation severity scores among animals treated with amitraz or cyfluthrin, and could not detect any differences between treatment types. However, a significant (P < 0.10) decreased pattern in severity scores from the beginning to the end of treatments was detected, suggesting a cumulative therapeutic value in repeated annual treatments across the 3-yr period. Additionally, the authors detected a lower median mite severity score between 2000 and a later capture in 2006. These positive outcomes may be the result of previous treatments during 2000-2002, but environmental covariates not accounted for could have been contributing factors. Avermectin drugs with longer release profiles may be a more effective treatment option in this and other small bighorn sheep populations that are compromised with mite infestations.

Original languageEnglish (US)
Pages (from-to)491-497
Number of pages7
JournalJournal of Zoo and Wildlife Medicine
Issue number3
StatePublished - Sep 1 2015


  • Bighorn sheep
  • mites
  • Ovis canadensis
  • parasites
  • Psoroptes
  • treatment methods

ASJC Scopus subject areas

  • Animal Science and Zoology
  • veterinary(all)

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  • Cite this

    Bleich, V. C., Johnson, C. K., Torres, S. G., Davis, J. H., Ramsey, J. M., Villepique, J. T., & Gonzales, B. J. (2015). PSOROPTES INFESTATION and TREATMENT in AN ISOLATED POPULATION of BIGHORN SHEEP (OVIS CANADENSIS). Journal of Zoo and Wildlife Medicine, 46(3), 491-497.