Udder cleft dermatitis and hock lesions in dairy cows - animal welfare problems in great need of preventive actions

The overall aim was to improve knowledge on udder cleft dermatitis (UCD) and hock lesions (HL) in Swedish dairy cows to improve prevention of these problems. Specific aims were to investigate the occurrence and risk factors for UCD and HL in dairy herds with free-stalls and milking parlour, and associations between UCD/HL and mastitis and culling. Other aims were to study duration, recovery, microbiota, and effects of a topical treatment for UCD. Three studies were performed, one cross-sectional in 99 herds and two longitudinal studies in 7 and 4 herds, respectively. Registrations of mild and severe forms of UCD and HL were performed together with potential risk factors. The studies showed that both UCD and HL are common among dairy cows, but that most cases were classified as mild. The prevalence varied markedly between herds. Only approximately one third of the UCD cases recovered spontaneously and those that did were mainly mild cases of short duration. Treatment with a topical spray containing chelated minerals did not affect the recovery of UCD. Differences were observed in the microbiota of UCD lesions compared to healthy udder skin, but there was no indication that UCD is caused by any specific infection. Several cow and herd level risk factors for prevalence and incidence of UCD and prevalence of HL were identified. There was no association between HL and mastitis/culling but the occurrence of new severe UCD increased the risk for clinical mastitis. The studies clearly showed that UCD and HL are multifactorial diseases. This project has generated important new knowledge on UCD and HL, which can be used to improve recommendations on prevention of these lesions. Better understanding of the development of UCD, important herd level risk factors for UCD and efficient treatment strategies are, however, needed.