Relationships between the shape of the hoof capsule and orientation of the distal phalanx in long toe underrun heels in donkeys

Abstract

A long toe underrun heel is one of the most common foot abnormalities in the horse industry (O'Grady, 2020). Long toe or low heel conformation showed smaller dorsal hoof angle and weakened, underrun or collapsed heels (O'Grady & Poupard, 2003). Long toe underrun heels in donkeys had a marked increase in the toe and heel lengths (HLs), and the toe curled proximally out of the weight-bearing surfaces. The dorsal hoof wall was concave or convex. The hoof capsule was oblong, the heels moved forward, and the apex of the frog extended. The solar surface had asymmetrical and elongation in the shape, and the heel width was reduced (Mostafa et al., 2018).The toe and heel angles (HAs) in long toe underrun heels were significantly decreased (p < 0.01) compared with the clinically healthy donkey (Mostafa et al., 2020). Long toe underrun heel was noted in 52% of sound performance horses (Turner & Stork, 1988), 77% of lame horses (Turner, 1986), 10% of unilateral lame horses (Dyson et al., 2011a) and 24.6% of donkeys (Mostafa et al., 2018). Recently,