Veterinary Science & Technology

Diagnoses of Primary Cause of Mortality in Domestic Sheep in the North American Intermountain West

Abstract

David J Wilson, Thomas J Baldwin and E Jane Kelly

Causes of death of 246 domestic sheep (Ovis aries) necropsied from 2009-2016 at the Utah Veterinary Diagnostic Laboratory were summarized. Sheep originated from Utah (93%), Idaho (6%) or Wyoming (0.4%). There were 54 fetuses, 21 4 week lambs (1-28 d old), 69 young lambs (29-180 d), 28 older lambs (181-365 d), and 74 adult sheep (>365 d). If no age was provided, age was estimated from body weight based on literature and expert opinion. Of the 48% of sheep with age provided, 91% matched with the body weight estimates. Primary cause of mortality was diagnosed in 228 cases (93%); 6 diseases accounted for 136 (60%) of the diagnoses: abortion 50 (22%), parasitism 29 (13%) (most from H. contortus), pneumonia 19 (8%) (95% bacterial), enteritis/enterotoxemia 17 (7%), bloat 13 (6%), and selenium deficiency 8 (4%). No cause of death was evident in 18 sheep (7%). The most common cause of fetal death was abortion 50 (93%). In 4 week lambs, most common causes were 4 pneumonia (19%), and 3 parasitism (14%). In young lambs, 15 parasitism (22%) (10 Haemonchus contortus), and 10 pneumonia (15%) (9 bacterial pneumonia) predominated. In older lambs, 7 parasitism (25%) (4 H. contortus, 3 Fasciola hepatica), 3 bacterial pneumonia (11%) and 3 clostridial enterotoxemia (11%) were most common. Most common causes of adult sheep death were 5 bloat (7%), 4 H. contortus (5%), 4 peritonitis (5%), 4 bacterial pneumonia (5%), and 4 urolithiasis (5%), a cause of death only found in adult sheep. Control measures for the most common causes of domestic sheep mortality include vaccination and clean lambing environment to reduce abortions, enterotoxemia and other infectious disease, control of parasite infestation, prevention and treatment of pneumonia and bloat, and adequate mineral supplementation.