The Characterization and Resolution of Hock and Knee Injuries on Dairy Cattle and The Relationship of These Injuries with Abnormal Locomotion
This thesis was an investigation into better understanding the prevalence of hock and knee injuries, and abnormal locomotion on dairy cows in Ontario, Canada, the relationship between injuries and abnormal locomotion, and if injury resolution occurs based on housing environment. A 52-week observational study took place to describe the relationship between mild, moderate, and severe hock and knee injuries and lameness in dairy cattle, and to determine if based on the type of hoof lesions present (non-infectious vs. infectious), and the treatment of regular hoof trimming, if cases of abnormal locomotion scores changed over time to become acceptable, and normal locomotion scores. Overall, the presence of moderate and severe hock and knee injuries were associated with abnormal locomotion scores. This association was further supported through the results on a larger dataset on the proAction Animal Care Assessment results for Ontario dairy farms. When following a regular hoof trimming schedule, it took around 50-days to see an improvement in locomotion score if a hoof lesion was present at the time of the trim. It is unknown if hock and knee injuries heal, based on descriptions of severity and complexity, and how long the healing process takes. A longitudinal observational study was developed to determine if hock and knee injuries heal or improve over time through facility transitions into housing environments that could promote healing, and how long this healing process takes. Fourteen commercial dairy farms were enrolled, 5 in Ontario and 9 in Nova Scotia, based on housing type and cow housing transitions made on the farm. A total of 598 cows were assessed for the presence of hock injuries using the Canadian proAction Animal Care Assessment scoring system. Overall, 77% of cows that transitioned with moderate hock injuries healed, 36% of cows with a severe hock injury, and 100% of cows with moderate knee injuries healed. Environments that promoted the most healing were deep bedded sand and pasture. The results of this thesis can help provide realistic timelines and expectations for dairy producers to implement corrective action plans to decrease the prevalence of injuries and lameness on their farms.