Risk factors associated with hair loss, ulceration, and swelling at the hock in freestall-housed UK dairy herds

Abstract

The objective of this study was to identify the risk factors associated with 3 presentations of hock lesions (hair loss, ulceration, and swelling) in freestall-housed lactating cattle. By independent identification and scoring of, and analysis of the factors associated with, hair loss, ulceration, and swelling, the aim was to identify whether risk factors were common to all 3, or differed among the presentations. A cross-sectional study was conducted on 76 herds in the UK during the winter housing period of 2007 to 2008, with a total of 3,691 cows examined for hock lesions. A randomly selected sample of approximately 50 cows in each herd were scored for body condition, lameness, cleanliness, rising behavior, and lesions at the hocks. For all cows, hair loss, ulceration, and swelling were scored separately on 4-point scales, with both left and right hocks scored. Based on a review of the literature, potential risk factors were identified and measured, collected from milk-recording data, or obtained through interviews with the farmers. Risk factors associated with hocks lesions in cattle were examined using data from the 2,982 cows housed in the 63 freestall-housed herds visited. Risk factors for each of the 3 lesion presentations were considered separately in multilevel logistic regression models, with moderate or severe hair loss, any degree of ulceration, and moderate or severe swelling as the outcome variables. Thirty risk factors were identified, none of which were common to all 3 lesion presentations. Five risk factors (locomotion score, number of days of winter housing, mean milk yield, freestall base material, and herd size) were common to both hair loss and ulceration. The stall bedding material was a common risk factor for both hair loss and swelling. A further 8, 5, and 11 risk factors were unique to hair loss, ulceration, and swelling, respectively. The existence of several differential risk factors between the 2 lesion presentations suggests that ulceration may not always be a direct extension of hair loss, as has been implied in previous scoring systems. Of the 12 risk factors associated with swelling, only 1 was common to another lesion presentation, which suggests that swelling may have a different etiology than hair loss and ulceration. The variables associated with the lesions indicate the importance of factors that affect the lying and rising behavior of the animal, including freestall structure and design, and the lying surface.