4 minute read
LAMENESS
Cryotherapy: Analgesia or Just Anti-inflammatory?
By Paul Basilio in the experimental group or at ambient temperature in Cryotherapy’s effects on inflammation are well known the control group. The contralateral limbs in each group in both human and veterinary medicine, but an accurate were outfitted with a standard gel orthotic. analgesic picture is still unclear. “After the treatment hour, the degree of lameness
To help fill in the gaps, Vivian Quam, MA, DVM, was assessed at 5, 10, 15, 20, 30, 45, and 60 minutes and colleagues designed an induced-lameness model post-treatment,” Dr. Quam said. “The screw was reapplicable to sport horses in competition. “The ultimate moved and lameness was assessed following removal objective is to understand how best to utilize cryotherapy to ensure that the method of lameness induction was as a tool for multimodal analgesia in our patients, as well not causing excessive pressure and pain that would as for a tool for safely managing the sport horse in com- persist following removal.” petition,” said Dr. Quam, from the Department of Veterinary Clinical Sciences at The Ohio State University. Results
In human sports medicine, cryotherapy has been Cryotherapy was maintained without difficulty for the employed commonly as an alternative or complemen- duration of treatment, and no changes in heart rate that tary therapy in elite athletes that face drug screening. It would indicate pain from treatment were seen. decreases synovial inflammation and knee pain in non- The degree of induced lameness did not differ beseptic joints for more than 24 hours, and intermittent tween cryotherapy and control groups, indicating that cryotherapy improves pain, function and swelling in lameness induction was successful and both groups had closed soft-tissue injuries. “It has also been shown to the same degree of lameness before and after induction. increase the pain threshold and pain tolerance at the “Both treatment groups experienced a reduction in site of cryotherapy application as well as at distal loca- lameness following the treatment hour,” Dr. Quam said. tions,” Dr. Quam said. “This suggests that a reduction “However, the cryotherapy had a statistically significant in nerve conduction velocity is the mechanism of ac- lameness improvement at 5 and 10 minutes after the tion for the analgesic effect of cryotherapy.” treatment period, indicating that the degree of lameness was improved at these points.” Testing the Unknown In the control group, however, there was only statisDr. Quam’s team hypothesized that 60 minutes of cryo- tical significance at 5 minutes post-treatment. No sigtherapy in an ice water slurry would produce an analge- nificant improvement in lameness was noted for either sic effect that could be observed with a noninvasive sen- group 15 minutes following treatment or in subsequent sor in horses with an induced forelimb lameness. assessments.
The researchers selected 10 mature research horses At 15 minutes, the lameness improvement was greatwith a normal physical examination and a negligible er for the cryotherapy group than for the control group. degree of observed lameness when trotted on a straight After 1 hour, the treatment group had a longer duraline, and all experimental procedures were conducted in tion of improved lameness vs. controls. In addition, 1° of accordance with IACUC standards. Study horses were lameness improvement was detectable in the cryotherasedated with IV acepromazine. The first dose was ad- py group, but only at 15 minutes of treatment. ministered prior to a 100-m baseline jog on grass, and “This study showed a modest reduction in lameness the second dose was administered while in stocks half- following 1 hour of cryotherapy, while the therapeutic way through the treatment hour. effect diminished over the post-treatment hour,” she
Each horse was assigned to the cryotherapy or con- said. “Significant lameness improvement could be detrol group during the first treatment period, and they tected at least 10 minutes after cryotherapy.” were then crossed over following a 2-week washout. This work serves as groundwork for further research
A farrier applied steel keg shoes to both forefeet. The that should determine the ideal method, duration and medial and lateral shoe branches had pre-drilled holes temperature for provision of analgesia, she said. “We at the level of the heel bulbs to induce an AAEP Grade could have missed a small analgesic effect over a longer 3 lameness via screw application. It should be noted that period in the study due to the small number of [horses] their transient lameness model was successful, in that a and high individual variability. Alternatively, the time of similar lameness level was noted before lameness induc- cryotherapy in this model may have been insufficient to tion and shortly after the study period. maintain an optimal effect of the hypothermia.”
The affected distal forelimbs were maintained at Dr. Quam discussed her research at the AAEP 65th 6° C using a cryotherapy boot filled with an ice slurry Annual Convention & Trade Show in Denver. MeV
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