Welfare in dairy cattle: Epidemiologic approaches for detection and treatment of lameness
Lameness in dairy cattle is one of the primary welfare concerns in the industry. The objectives of this thesis were to investigate the use of an accelerometer for early detection of lameness, to describe the etiology and temporal changes in hoof lesion prevalence, and to assess treatments for two types of lesions that commonly cause lameness. The Pedometer Plus™ was first validated for lying behaviour and activity measurements and determined to accurately collect data on lying and on leg movement in the cow. This system was then used to determine if changes in activity and lying behaviour could be observed during presence of hoof lesions or during lameness. Lame cows decreased their activity and increased daily lying duration compared to non-lame cows. Activity, lying duration, and lying bouts were found to be altered with particular hoof lesions compared to cows without painful lesions. Lying duration was increased in periods where cows had painful lesions compared to periods when cows had no painful lesions present on their hooves. Digital dermatitis and sole ulcers were the most commonly observed painful hoof lesions. Presence of these lesions increased the odds of a cow having that lesion later in life. Additionally, the odds of developing a sole ulcer were higher in cows that had previously had hemorrhages. A randomized clinical trial compared the use of a tetracycline hydrochloride paste to use of a bandage or no treatment in digital dermatitis lesions. Lesion healing rates did not differ between the two treatments, while both were more effective than the negative control. An algometer was used to quantify pain at the lesion site and to verify decreasing pain responses between active, healing and healed lesions. The effect of therapeutic hoof block application on sound dairy cows was assessed, with lactating dairy cows randomly assigned to receive a block (n=10) or no treatment (n=10). Block application had little effect on the activity, lying behaviour and production of sound lactating dairy cattle. Application was associated with increased gait abnormality. These results provide potential dairy cattle welfare improvement through early identification and treatment of hoof lesions and lameness.