Ice application without water drainage supports optimal hoof cooling in adult horses

Abstract

Cryotherapy is often used to reduce inflammation in acute equine laminitis cases. Certain hoof temperatures have been suggested as effective in minimizing the inflammatory process; however, there is limited evidence on which methods are best at achieving these temperatures. Our objective was to determine how different methods of cryotherapy influence the rate and extent of cooling for the equine hoof wall. Four horses received three hoof cooling treatments and a control (CON; no treatment application) in a 4 × 4 Latin square design. Treatments included (1) ice surrounding the hoof in a 5 L fluid bag with water drainage holes (DB), (2) ice surrounding the hoof in an undrained bag (UB), and (3) ice in a commercial wader boot (CW). Hoof wall temperatures were collected via thermal imaging for 12 h. Thermally imaged body temperatures and thermometer-based rectal temperatures, heat index, relative humidity, and ambient temperature were recorded. A treatment × time interaction (P < 0.001) was observed for all hoof temperatures. All treatments differed from CON after 2 h post-application, with the UB treatment resulting in the greatest and most sustained reduction in hoof temperatures over the 12 h period (a change of −23.7 °C ± 1.6). The wader boot showed similar trends to the UB treatment but was poorly tolerated by the horses. Environmental effects differed between hoof and body surface. Our findings indicate that cryotherapy treatments that maintain an ice-water slurry around the hoof result in greater decreases in hoof temperatures 2 h post-treatment compared to drained ice application.