Udder cleft dermatitis in dairy cows

Abstract: Udder cleft dermatitis (UCD) is a skin condition that affects dairy cows at the fore udder attachment or between the udder halves. The lesions range from mild (eczematous skin changes) to severe (open wounds and large crusts) and may impair the welfare of the affected animals. This thesis aimed to increase the understanding of the epidemiology and etiology of UCD in Swedish dairy cows.In the first part of the project, we assessed the prevalence of mild and severe UCD and found that the condition is common in Swedish dairy cows, and we also found several cow- and herd-related risk factors associated with having UCD. Some risk factors were common to both mild and severe UCD, whereas some only affected one type of UCD.In the second part of the project, we investigated the incidence, duration and recovery of UCD in seven herds, and analysed cow-related factors associated with transitions from being unaffected to having UCD, as well as factors associated with recovery. The incidence was high in the investigated herds, and risk factors for a transition to UCD were similar to those associated with having UCD. The duration of UCD was often long, particularly if the cow had severe UCD. Cows with severe UCD and cases with long duration had low chance of spontaneous recovery from UCD, and older cows also had a lower chance of recovery than younger cows. We also performed a study in four herds, testing a spray with copper and zinc as a topical treatment of UCD, but found no positive effect on UCD recovery in the treated cows compared to the control group.In addition, using shotgun metagenomic sequencing of swab samples, we investigated the microbiota in UCD lesions in comparison to healthy skin, and found that UCD lesions had a decreased bacterial diversity compared to healthy skin but that no specific pathogen was associated with the development of UCD.Associations between UCD and mastitis were analysed, and a transition to severe UCD was associated with an increased risk for mastitis, but mastitis-causing pathogens were not a common finding in the UCD microbiota.In conclusion, this project has led to an increased understanding of the epidemiology and etiology of UCD in Swedish dairy cows that can be used in prevention of the disease.