EVALUATION OF HEALTH STATUS OF ROCKY MOUNTAIN SHEEP (OVIS CANADENSIS CANADENSIS) IN SOUTHEASTERN BRITISH COLUMBIA

Abstract

Three herds of Rocky Mountain bighorn sheep (OVis canadensis canadensis Shaw) in southeastern British Columbia were evaluated for health status during 1983 and 1984. Each herd was of similar size but varied in disease occurrence and herd dynamics, both historically and over the period of study. Samples taken from six sheep in each herd were examined for nutritional condition, microbiological, virological and serological status, general and pulmonary parasite loads, blood chemistry and trace mineral levels, as well as gross and histological lesions. The Columbia Lake herd at high animal density wintering on a poor quality, low elevation range was demonstrated to have high levels of lungworm infection, low total serum protein, fecal nitrogen and liver selenium levels. Higher total serum protein, fecal nitrogen, liver selenium levels and lower lungworm levels were present in bighorns from the lower density ER herd wintering at high elevation. Adrenal glands were larger, lungworm levels were lowest, and chronic clinical and subclinical systemic and respiratory diseases were common in adults and lambs from a second herd (Wigwam) wintering at low elevation, 2 years after an all-age die off. Study herd status was best determined by comparison of fecal lungworm larval output, fecal nitrogen, liver selenium levels and pathological findings. Recommendations were made for future monitoring and management of bighorn herds. The Columbia Lake herd was treated with trace minerals and an anthelmintic after the 1983 collection. Lungworm larvae output was less in four sheep examined in the following year, but no change was seen in trace mineral levels.