An Estimation of Lameness in Sable Island Horses Using Radiographic Evaluation of the Distal Phalanx and Hoof Capsule

Laminitis is a painful condition that causes lameness in horses. However, monitoring this condition in feral horses is logistically difficult. Laminitis can be detected postmortem, as inflammation of the sensitive laminae of the hoof changes the relative location of the bony structures within the hoof capsule. Thus, evaluation of cadavers may be used to estimate laminitis prevalence in feral populations of horses. The objective of this study was to estimate the prevalence of laminitis in feral horses inhabiting the Sable Island National Park Reserve, Canada, using radiographic imagery on the hooves of naturally deceased horses. Radiographic indicators evaluated included coronary band extensor process distance (CE), capsular rotation (CR), palmar angle (PA), ratio of the dorsal hoof wall thickness to the length of the distal phalanx (DHWT:P3) and sole depth (SLD). Each value measured indicated the following prevalence of laminitis: CE 0% (97.5% Confidence Interval (CI) 0-4.51%), 8.75% CR (95%CI 3.59-17.2%), PA 25% (95% CI 15.99-35.94%), DHWT:P3 6.25% (95%CI 2.06-14.0%) and 65% SLD (95% CI 53.52-75.33%). The majority of indices measured for laminitis were low. These findings suggest that laminitis is fairly infrequent in the Sable Island horses evaluated in this study.