Udder cleft dermatitis in dairy cows – epidemiological and microbiological studies

Udder cleft dermatitis (UCD) is a skin condition that develops at the fore udder attachment, or between the udder halves, of dairy cows. The UCD lesions vary in appearance from mild, eczematous skin changes, to severe, with wounds that often become large, foul smelling and purulent. The lesions impair the welfare of affected cows and may also become a hygiene issue during milking. In addition, a previously conducted Swedish study found associations between UCD and mastitis. It is not clear why UCD lesions develop, although some risk factors have been identified. The aim of the thesis was to increase the understanding of the prevalence of UCD in Swedish dairy cattle herds, and to analyse potential risk factors for UCD. In addition, microbiological studies were performed to see which microorganisms are present in the lesions, and how the microbiota of UCD lesions differ from that of healthy skin.

First, a cross-sectional study in 99 free-stall dairy cattle herds with milking parlors was performed, and the second part included a longitudinal study in seven herds with herd visits every 6 weeks during one year. Herd visits were performed during milking, and the cows were examined for UCD in the parlor. In addition to scoring UCD, the hygiene and udder shape of each cow were evaluated, and the farmer or staff were asked questions about management routines and other herd factors. We also took samples from recently developed UCD lesions to investigate the microorganisms present in the lesions and compare them with samples from healthy skin at the fore udder attachment from cows without UCD, and a treatment study was conducted in four of the herds, in which a spray containing copper and zinc was tested as treatment against UCD.

The results showed that UCD is common in Swedish dairy cows, as almost one third of the more than 3,000 cows that were examined in the cross-sectional study had mild (18%) or severe (9%) UCD. The lesions often had a long duration, particularly severe UCD, and the chance of recovery diminished the longer the cow had had UCD. Recurrent cases of UCD was also common.

A higher risk for UCD was seen in cows of the Swedish Red breed, compared to Swedish Holstein cows. Cows with a certain udder shape also had higher risk of UCD, mainly cows that lacked a strong fore udder attachment and cows with an indentation or fold at this attachment. UCD was also more common in older cows and older cows also had less chance of recovery. Cows with high milk production had a higher risk of severe UCD lesions, and we also found that mild lesions often became severe. The microbiological investigations revealed that both mild and severe UCD lesions had a deviating microbiota compared to healthy skin. On healthy skin, a high diversity was seen, whereas the UCD lesions more often had a high proportion of a single type of bacteria. However, it was not the same type of bacteria that were found in all UCD lesions, and the results indicate that no specific microorganism cause UCD. An association between severe UCD and mastitis was found, but it is not known how UCD affects the risk for mastitis. The topical treatment that was tested had no positive effect on the recovery from UCD. Further studies on UCD are warranted to reveal more about the underlying causes of UCD and to identify effective treatment strategies.

Lisa Ekman received her postgraduate education at the Department of Clinical Sciences, Swedish University of Agricultural Science, Uppsala, Sweden, while working at the National Veterinary Institute, SVA. She obtained her degree in veterinary medicine in 2014 at the Faculty of Veterinary Medicine and Animal Science at the same university.

Text and picture: Lisa Ekman