Distal limb immersion in ice and water is the most effective means of cooling the equine hoof lamellae under clinically relevant conditions

OBJECTIVE To determine the relationship between hoof surface (HS), hoof wall (HW), and lamellar tissue (LAM) temperature during distal limb cooling and evaluate 4 cooling methods in ambulatory horses over extended periods using HW to estimate LAM temperature. METHODS 8 healthy, university-owned horses were enrolled. Temperature was measured over 4 hours at LAM, HS, and HW for 4 cooling methods: ice sleeve (SLEEVE), ice pack system (ICEPACK), low-volume ice water immersion (LV-IMMERSION), and high-volume ice water immersion (HV-IMMERSION). The relationship between HW, HS, and LAM was mathematically modeled, generating a method-specific correction factor to predict LAM based on HW. Hoof wall temperature was then measured over 8 hours with horses free in a stall (LAM was estimated using HW). Mixed-effects linear regression was used to compare cooling methods. RESULTS HV-IMMERSION and LV-IMMERSION significantly decreased LAM temperature over 4 hours (P < .001), whereas ICEPACK and SLEEVE did not. Lamellar tissue temperature estimated using HW showed good concordance (rho c = 0.93 [0.93 to 0.94]; P < .001) and correlation (r = 0.93; P < .001) with measured LAM temperature. In horses free in the stall for 8 hours, the estimated LAM temperature decreased significantly with HV-IMMERSION (-20.4 degrees C [-22.9 to -17.8]) and LV-IMMERSION (-14.9 degrees C [-17.7 to -12.1]) compared to control (32.7 degrees C [32.2 to 33.2]; P < .001) but did not decrease with ICEPACK (-2.7 degrees C [-5.6 to -0.3]; P < .08) or SLEEVE (-1.8 degrees C [-5.6 to -2.0]; P < .4). CONCLUSIONS HV-IMMERSION and LV-IMMERSION were superior to ICEPACK and SLEEVE for lamellar cooling. CLINICAL RELEVANCE Immersion of the distal limb in ice and water is most effective for cooling the digital lamellae under clinically relevant conditions.