Effects of season, herd size, management system and veterinary practice on the lameness incidence in dairy cattle.

The incidence of lameness in herds visited by veterinary practitioners in winter (0.87 cases per 100 cows per month) was greater than in summer (0.71 cases per 100 cows per month). The relative proportions of leg lesions and underrun heel were higher, and those of foul-in-the-foot, interdigital hyperplasia and foreign body in the sole were lower in winter than in summer. In winter, leg lesions and aseptic laminitis were most common in cows housed in cowsheds, white line abscess in cows in strawyards and sole ulcer in cows in either cowsheds or cubicles with concrete yards. The overall incidence of lesions was lower in strawyard accommodation (0.71 cases per 100 cows per month) than in cubicles with yards (0.93 cases per 100 cows per month). Veterinary practitioners saw proportionally fewer cases of foul-in-the-foot but proportionally more cases of sole ulcer in larger than in smaller herds. The animal incidence of lameness ranged from 1.7 to 11.4 per cent among practices; in 20 practices which recorded a total of at least 100 lesions in both summer and winter there was a large variation in the proportions observed of each lesion. A principal component analysis contrasted those practices which tended to see mainly cases of white line abscess, white line separation, foul-in-the-foot and leg lesions with those which saw mainly cases of underrun heel, interdigital hyperplasia, punctured sole with pus and sole ulcer. Twenty-nine per cent of cases of underrun heel and 22 per cent of cases of both deep sepsis and interdigital hyperplasia occurred in conjunction with another lesion.