The effects of farming system and season on the prevalence of lameness in sheep in northwest Iran.

Abstract AIMS: To determine the prevalence of lameness in sheep in Urmia, northwest Iran, and compare the effects of production system and season on prevalence. METHODS: A cross-sectional study, using cluster sampling, was conducted. The selected flocks included 18 with 2,315 sheep from farmed production and 28 with 7,619 sheep from semi-migratory systems, and were visited once in summer (grazing season) and once in winter (housing season). Sheep showing signs of lameness were examined to detect the causes of lameness. Bacteriology and histopathology were also performed if required. RESULTS: The probability of overall lameness was not affected by farming system (p = 0.40), but in the grazing season was less (OR = 0.62; 95% CI = 0.56–0.69) than in the housing season. Footrot was most the common cause of lameness, occurring in 1,047/1,880 (56%) cases. Among flocks, 40/46 (87%) had ≥1 case of footrot. Farming system had no effect on occurrence of footrot (p = 0.85), but the probability of footrot in the graz...