Cryotherapy Methods for Laminitis Treatment Compared (AAEP 2010)

Recent surveys of equine veterinarians reveal that laminitis is the No. 1 lameness concern of equine practitioners, due how difficult it is to treat and manage this debilitating condition. On the topic of laminitis control, Heidi Reesink, VMD, a veterinary resident at Cornell University, discussed a comparison of three methods of cryotherapy (cold treatment) as measured by blood vessel temperature in the foot. Reesink noted that cryotherapy is the only treatment shown to prevent development of acute laminitis, calling it the "gold standard."

Chris Pollitt, BVSc, PhD, (2004) demonstrated the safety of prolonged immersion of the distal limbs for 48 hours to abolish associated lameness and to minimize pathologic changes related to laminitis. Reesink explained that cryotherapy controls hoof inflammation by potentially lessening metabolic tissue demands, directly inhibiting temperature-dependent enzymes, and/or reducing blood-borne delivery of inflammatory mediators.

Reesink and her colleagues set out to examine if ice-filled wader boots would be more effective at cooling the hoof than other methods. They compared an ice-filled wader boot to packing the feet to the level of the fetlock by filling 5-liter fluid bags with crushed ice slurry, or using gel ice packs replaced at 60-minute intervals. The opposite (nonchilled) limb of each horse was used as a comparative control. Reesink also wanted to determine if digital venous temperatures would approximate laminar temperatures, and if digital venous temperatures would be slightly warmer.

Nine healthy horses free of lameness or laminitis were used in the study. Before the researchers applied any trial therapy, they took pre-treatment baseline temperature readings for 15 minutes. Then they tracked each 120-minute treatment method, with periods of rewarming between each treatment. Treatment time was based on previous studies that showed minimal additional cooling is achieved after two hours of ice immersion.

The investigators obtained temperature measurements every minute during each treatment, using thermocouples (which are capable of transmitting temperature readings on an ongoing basis) placed in blood vessels in both forelimbs. Treatment began with two hours in the gel boot, after which the leg allowed to rewarm. Then came two hours in the ice bag, and after a final rewarming, two hours in the wader boot. Minimal cooling occurred in the gel boot, whereas in the ice bag and wader boots dramatic temperature decreases in both laminar and venous blood were achieved. Laminar temperatures remained slightly cooler than venous temperatures, as expected.

Reesink stressed the clinical relevance of this study, which demonstrated that 5-liter fluid bags filled with ice slurry provide a practical and affordable method of cryotherapy, whereas a gel ice boot is ineffective.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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