BACTERIA ISOLATED FROM NASAL AND TONSILLAR SAMPLES OF CLINICALLY HEALTHY ROCKY-MOUNTAIN BIGHORN AND DOMESTIC SHEEP

Nasal and tonsillar samples were collected from 14 free-ranging clinic ally healthy Rocky Mountain bighorn sheep (Ovis canadensis canadensis) and 10 domestic sheep (Ovis aries). We identified 194 bacterial isola tes, including 101 from bighorn and 93 from domestic sheep. Of these i solates, 115 were gram-positive and 79 were gram-negative. Staphylococ cus species were the most numerous gram-positive organisms and had a h igher incidence in samples from domestic than from bighorn sheep. In c ontrast Streptococcus species were present in higher numbers in sample s from bighorn sheep. Pasteurella haemolytica, the most common gram-ne gative bacterium, was isolated from five of five tonsillar but from no ne of ten nasal samples of domestic sheep, and from seven of eight ton sillar and three of ten nasal samples of bighorn sheep. Most bacteria isolated were considered opportunistic pathogens. However, of the bact eria isolated, P. haemolytica, P. multocida, and Actinomyces pyogenes are most frequently associated with respiratory disease.