Strategic palmar trimming before conventional shoeing shows potential for managing underrun heels in horses [version 1; peer review: 1 approved with reservations]

Background: This study aimed to investigate the potential of strategic palmar trimming before conventional shoeing for managing hoof malconformation in horses with underrun heels. Methods: Eleven affected horses were divided into control (5 horses with 14 defective hooves) and experimental (6 horses with 16 defective hooves) groups. The experimental group underwent strategic palmar trimming before conventional shoeing, while the control horses received regular trimming before traditional shoeing. Dorsal hoof wall angle (DHWA)/heel angle (HA) ratios, heel-bulb distance, and six parallel lines indicating solar surface dimension were determined before, and after 5, 10, 15, 20, 25, and 30 weeks of the different farriery protocols. Palmar trimming distance was only measured in experimental horses. Results: A group-by-time interaction was observed for DHWA/HA ratios and solar surface dimension. Separate effects for group and time were observed in the heel-bulb distance. A modification in hoof conformation was detected at 25-30 weeks only in horses in the experimental group, including decreases in DHWA/HA ratio, heel-bulb distance, and palmar trimming distance, coinciding with an increase in palmar width of trimmed hooves. Conclusions: Different trimming protocols produced a different effect on hoof conformation. Therefore, tactical remedial trimming can potentially control poor hoof conformation in horses with underrun heels.