A longitudinal study of the hooves of non-lame cows

A longitudinal study of the feet of cows from a seasonal dairy herd was conducted over a 12 month period to measure the occurrence of subclinical hoof lesions. Eleven 2-year-old cows, entering the herd for the first time, and eleven mature cows were randomly selected from a herd of 415 cows at the end of winter (July 1989) prior to calving. The incidence of lameness in the herd over the 12 months was 2%. None of the trial cows became lame during the study. Cows were examined monthly. The type, severity and location of any hoof lesions were recorded. Sole haemorrhage, erosion of the heel bulb and minor white line separation were the most commonly observed lesions. These lesions were observed with specific claw distributions in the cow and at specific times of the year and breeding season, with waves of each type of lesion passing through the herd at a particular time. White line separation was observed commonly during spring (up to 37% of digits affected), disappeared almost completely over the dry summer months and reappeared in autumn, increasing to 40%' again over winter. Lesions were more commonly observed in the lateral digits, with fore feet being more commonly affected than hind feet. Erosion of the heel bulbs was common in August (65% of digits affected, more common in mature cows than 2-year-olds), disappeared quickly during spring, and reappeared in all cows during the following winter (88% of digits; no age differences). There were no differences in distribution between digits. Sole haemorrhages were concentrated over the mid-sole and abaxial sole zones. They were more common in the hind feet than the front feet and more common in the outside claws (p < 0.001). Haemorrhages were not observed prior to or soon after calving, appeared in October and reached a peak of 40% in December, then gradually disappeared by the time of drying-off in May. The 2-year-olds were more frequently affected than the mature cows (p <0.001).