Prevalence and risk factors for udder cleft dermatitis in UK dairy herds

Udder cleft dermatitis (UCD) is an endemic disease in dairy cows, initially presenting as skin lesions, which can lead to ulceration and deep, persistent infection. Early lesions may go undetected due to their location deep in the intermammary cleft. There is little existing evidence on the prevalence of UCD in dairy cattle in the United Kingdom (UK), but studies in other European countries with similar climates and dairy production systems have found prevalence to be highly variable between herds. The aim of this study was to investigate the prevalence, severity, and location of UCD lesions in UK dairy herds, as well as to explore potential risk factors for the disease at both the cow and herd level. An observational cross-sectional study was carried out, with 8,302 cows examined for UCD lesions on 28 farms. All participating farms were recruited via random selection from the client list of a single large animal practice. Data were collected by the research team in the parlor during routine milking or in locking head yokes in herds with automatic milking systems. The presence, severity, and location of any UCD lesions were recorded. In addition, fore udder attachment score, udder depth score, body condition score, hock score, and cleanliness score were recorded. A questionnaire was also used to collect additional information about the herd. Descriptive statistics were compiled in Microsoft Excel, then data were transferred to IBM SPSS for further analysis. Within-herd prevalence of UCD lesions ranged from 0.7% to 27.4%, with 9.9% (95% CI: 9.3%-10.6%) of all sampled cows being affected. In total, 39.6% of cows with lesions (3.2% of all cows examined) were classed as having very severe lesions greater than 5 cm in size. A 2-level logistic regression model, with cows clustered within herds, was used to explore risk factors for the presence of UCD lesions. Cows with strong fore udder attachments and tight udders had lower odds of lesions, whereas those with loose fore udder attachments and deep udders had higher odds. The final model selected explained only 12.5% of the variance, suggesting that there are likely other cow- and herd-level variables associated with the presence of lesions, which were not captured. The association between udder conformation and UCD lesions suggests that this may be a key area of focus for reducing prevalence of this disease. However, the findings should be interpreted with caution, as the primary focus of the study was to accurately describe prevalence in UK herds, rather than to explore risk factors. Further work is needed to explore additional risk factors and examine the progression of these lesions over time.