Abstract #267

# 267
Hock injury healing through facility transitions on dairy cattle in Canada.
A. M. Armstrong*1, J. Schenkels2, T. F. Duffield1, D. B. Haley1, D. F. Kelton1, 1University of Guelph, Guelph, ON, Canada, 2Atlantic Veterinary College, Charlottetown, PEI, Canada.

Hock injuries are prevalent across the dairy industry, with recent benchmarking in North America showing that cows managed in intensive systems are at a higher risk for injury development. It is unknown which hock injuries heal based on descriptions of severity and complexity, and how long the healing process takes. The objective of this observational study was to determine if hock injuries heal or improve over time through facility transitions into more ‘cow friendly’ housing environments, and how long this healing process takes. Fifteen commercial dairy farms were enrolled, 5 in Ontario and 10 in Nova Scotia based on housing type and transitions made on the farm. The transitions were to facilities with mattresses, sand, pack or pasture cow resting areas. Mattresses were considered the least ‘hock friendly’. A total of 682 cows were assessed for the presence of hock injuries using the Canadian proAction Animal Care Assessment scoring system. Hock injuries with scores of 0 or 1 on the 4-point scale are deemed acceptable, and scores of 2–3 are unacceptable, and require corrective action. Cows were scored for 14-weeks in their new environment. The preliminary results are from the 10 farms, and 292 cows assessed in NS. Eighty-one cows that started their facility transition with a hock injury score that required corrective action met the inclusion criterion and were included in the survival analysis for time to healing. The analyses were completed using Stata/SE 15.0, with a significance level of P = 0.10 for the preliminary analysis. A Cox proportional hazards model was fit for hock injury healing with stall base as the predictor. Hock injuries healed 6.00 times faster on sand (P = 0.001, 95% CI: 2.04–17.7), 3.08 times faster on packs (P = 0.096, 95%CI: 0.82–11.6), and 5.81 times faster on pasture (P = 0.001, 95%CI: 2.08–16.6) compared with mattresses. Based on the preliminary results, hock injuries are more likely to heal, and heal faster when cows transition to more cow ideal housing conditions. These results will provide the dairy industry with information on what housing environments are best for resolution of injuries to occur, as well as a timeline for resolution.

Key Words: hock injury, healing, welfare