TOOLS OF REHABILITATION ~ Part One ~
SARAH PLEVIN | BVMS, MRCVS, CVA, DABVP, DACVSMR, RCVS SPECIALIST The goal of veterinary rehabilitation is to restore the animal to its rates.2,3 Long periods of cold application have not been shown prior level of activity while preventing further injury. There are to negatively affect the horse, unlike in humans where negative numerous rehabilitation tools on the market today, all claiming a effects have been reported after 30-45 minutes.4 more expedient and successful recovery from injury. Anecdotal reports suggest beneficial effects from a variety of treatment Additionally, while periods of transient vasodilation (the 'hunting modalities: however, objective evidence to support them is largely reaction') caused by dilation of blood vessels in muscle tissue lacking. Extrapolation from the human field is commonplace have been observed in human limbs exposed to low temperatures, but is complicated by differences in skin thickness and anatomy this phenomenon has not been observed in experimental local between horses and humans. Consequently, therapeutic regimens cryotherapy applied to the equine distal limb, presumably due to are often recommended by the manufacturer of equipment the lack of skeletal muscle in that area.4 and not by equine-specific scientific research. This article will review some of the most frequently used equine rehabilitation modalities. For each, there will follow a summary of its use, its EQUINE-SPECIFIC SCIENCE mechanism of action, scientific evidence to support its use, and a Although cold therapy is a basic and extremely common treatment modality, few controlled studies investigating the optimal form of brief discussion about how we use it in our practice. cryotherapy in the distal limb of the horse exist.
HYDROTHERAPY
The most relevant clinical studies include comparison of wet interface (ice water immersion or ice boots) versus dry Hydrotherapy is any form of therapy utilizing water. Several interface application (cold pack or pneumatic sleeve) to the equine metacarpal area. A profound and superior sustained treatment modalities exist. reduction in deep tissue temperature has been reported with ice water immersion or ice boot application compared to either 1. COLD THERAPY (CRYOTHERAPY) dry interface technique, with a pneumatic sleeve being the only This is the therapeutic cooling of tissues. It is used for acute soft dry interface modality to achieve tissue temperatures within tissue injuries and is frequently a first line treatment. the therapeutic range in one study. Additionally, other studies have reported the combination of ice water and compression to be optimal at reducing tissue temperatures. These studies have MECHANISM OF ACTION also shown that cold pack-therapy alone is unable to effectively There are three main local effects reported when cold is applied cool soft tissue structures deeper than two to three centimeters, to any living tissue: regardless of application duration.2,5,6,7,8,9 1. Analgesia: due to a reduction in conduction velocity of peripheral nerves, increasing both the threshold for A commonly used commercial boot that uses ice water and stimulation and the refractory period after stimulation. intermittent compression is the Game Ready® system. However, 2. Hypometabolism: cold tissues have a reduced metabolism when ice and compression (in the form of ice bags and an elastic and therefore a reduced requirement for oxygen, glucose and bandage) were compared to the Game Ready® system in humans other metabolites. This phenomenon is thought to protect the ice and bandage model was found to be superior.5,10 Despite tissues on the periphery of an injury from secondary hypoxic this, the simplicity and ease of use of commercial systems make damage. In addition, hypometabolism "down regulates" pro them a very appealing and practical option. inflammatory cytokines and protease enzymatic activity. 3. Vasoconstriction: reducing the regional inflammatory 2. CONTRAST THERAPY response by reducing perfusion and edema.1 Contrast therapy is characterized by the repeated alternating applications of cold and heat. It is used to aid post-exercise Tissue temperatures ranging from 10-19°C have been recovery and to treat acute soft tissue injuries with the aim of reported to be necessary to maximize the physiologic effects increasing blood circulation through cyclic vasodilation and of vasoconstriction, pain relief and a decrease in metabolic vasoconstriction.
22 The Practitioner
Issue 4 • 2020