Equine physical therapy: Writing the exercise prescription
Equine physical therapy (PT) has been a subject generally avoided by veterinarians, and often delegated to para-professionals with varying degrees of training.
The lack of teaching in this field has caused it to become something of a "black box"-a treatment modality that we recognize as potentially beneficial, but that we brush over because of a lack of understanding.
No veterinarian would simply write a prescription for medication, without providing the specific drug, dosage and frequency of administration.
Equine practitioners regularly prescribe pharmaceuticals, selected surgical procedures, nutritional supplements, even corrective shoeing, while PT remains the "last frontier."
The large number of treatment modalities available - various massage techniques, therapeutic ultrasound, hot and cold packs, electrostimulation - engenders confusion. These specific regimes should not be viewed as primary components of therapy, but rather as ancillary aids; the "modalities" are to physical therapy what anti-inflammatory agents can be to surgery-when used properly, they are beneficial. Scientific research is lacking in equine PT, and the prolific articles in lay journals seem sometimes to increase the confusion.
PT's backbone is the exercise prescription. The prescription is based on:
* Clinical diagnosis,
* A thorough understanding of the equine muscular system, and
* Performance requirements of the patient.
A better understanding of the principles of physical therapy is necessary if the veterinarian is to appropriately advise the client and direct the para-professionals attending the patient.
Understanding the muscular system
While muscular anatomy is relevant, it is more important for us to understand muscle function. Muscle is a dynamic tissue, with every action-from blinking an eye to performing a dressage test - involving the orchestrated contraction and relaxation of specific muscle groups. When this orchestration fails, injury occurs; when injury occurs, physical therapy is required to restore full function.
Normal muscle function implies both strength and flexibility. A healthy muscle must be strong enough to perform without injury. Muscle weakness is a consequence of athletic injury. Hence, restoration of strength must be a key component of any rehabilitation program.
Flexibility is defined as the ability of the muscle to relax ("let go") and yield to passive stretch (like a rubber band). It is necessary for smooth agonist-antagonist activity. Lack thereof sets the stage for muscle tears and stiffness. The restoration of flexibility is as important to the outcome as the restoration of strength.
The commonly identified muscular dysfunctions in the equine athlete are muscle deficiency (weakness or stiffness), tension, and muscle spasm. Tension is defined as muscle contraction beyond physiological needs. Muscle spasm is a reflexive contraction mediated at the spinal cord level, presumably designed to protect and immobilize an injured part. Muscle spasm is a component of all acute injuries-as the reactive tissue of the musculoskeletal system, muscle responds to insult in the only way it can-by contracting. Persistent muscle spasm is a painful pathologic contraction resulting in limitation of motion and continued morbidity.
The attending veterinarian should evaluate all acute athletic injuries, and perform diagnostic imaging as indicated.
PT in the form of immediate controlled mobilization is the treatment of choice for most acute injuries not requiring surgery. Immobilization is required when there is anatomic instability (i.e., most fractures). Controlled mobilization is indicated for most soft tissue injuries, including partial tendon tears ("bowed" tendons).
The benefits of early mobilization include:
* Increased local circulation to enhance healing,
* Reduced swelling via improved lymphatic and venous drainage,
* Prevention of motion-limiting adhesions, and
* Restoration of the muscular system to earlier function.
When applied properly, recovery time is shorter and more complete than when using conventional methods.
Mobilization must be controlled. Excessive exercise causing lameness or pain is contra-indicated; pasture turn-out is not advisable, as the exercise is totally uncontrolled. Mobilization is most effective when instituted immediately following injury, as long as it is performed in a controlled fashion under veterinary supervision.
Immediate controlled mobilization
In the acute phase, the goal of treatment is to gently restore function while reducing pain and swelling. Cold hydrotherapy or ice is effective in reducing swelling and alleviating pain. Cold is used to provide local analgesia; during cold therapy, the injured part is very gently manipulated to gradually restore normal motion. Manipulation should follow the natural motion of the joint. Easy motion within the comfortable range serves to slowly break muscle spasm. Active motion, with gentle muscle contraction is beneficial as it activates the "lymphatic pump." For leg injuries, this active motion can be accomplished by "asking" the horse to pick up its foot as if to pick out the hoof. This motion may be repeated a few times, and the affected joint(s) gently passively flexed and extended.
Only a few repetitions (five repetitions maximum) of this flexion exercise are required; excessive repetitions cause fatigue and stiffness. During the acute phase, frequent short therapy sessions are required (ideally, every two hours); as treatment progresses, a twice-daily schedule is recommended. We have developed a simple regimen of equine distal limb exercises, which are easily performed by owners or caretakers. All exercises should be comfortable for the patient. Stretching is contraindicated in the acute; stretching a muscle in spasm causes tearing of fibers, producing more pain. Although the patient may be "sore," there should be no indication of pain, such as flinching or sudden retraction of the limb. The horse should be relaxed and willing during the therapy sessions, and should show an increased level of comfort following treatment.
Light hand walking is indicated when the horse can walk without apparent lameness. Stall rest and bandaging for support are required to prevent overuse of the injured part. Gradually, a controlled exercise program can begin.
Controlled exercise program
A controlled exercise program may be instituted for rehabilitation of athletic injuries, for post-operative rehabilitation, or for chronic orthopedic conditions (such as navicular syndrome and osteoarthritis). Equine athletic careers are prolonged by judicious use of controlled exercise programs because general fitness can be maintained.
When managing musculoskeletal injury, the necessity of complete rest is the exception rather than the rule. Following acute injury, hand walking is advised as soon as lameness is no longer evident. Light trotting is instituted gradually, on an as-tolerated basis. Lameness, and increased local tenderness, heat or swelling are indications that exercise has been excessive. Local adjunctive therapy, such as cold hydrotherapy, is used in addition to exercise. Support wraps are advisable, as is regular shoeing, with attention given to prevailing conditions.
The exercise prescription should be modified weekly at first, then monthly, based on veterinary examination and diagnostic imaging when appropriate. An exercise prescription should include the following components as a minimum:
* Range of motion exercise, when applicable; specific exercise(s) and number of repetitions (i.e., flex carpus five times) and frequency per day;
* Specifics of general exercise (e.g., walk in hand five to 10 minutes per day);
* Shoeing prescription;
* Medications ordered;
* Ancillary aids, such as hydrotherapy, massage, and leg bandaging.
An open conversation with the owner and/or trainer is imperative. The exercise prescription may be modified depending on the handler's abilities, the facilities, and the horse's disposition. It is the veterinarian's duty to caution against potentially harmful practices. The following are contraindicated:
* Anything that produces increased swelling, such as the use of heat in acute leg injuries;
* Anything which causes discomfort to the patient, such as excessive manipulation of an injured part, activity producing lameness, or stretching a muscle in spasm; any therapeutic modality which is unpleasant to the horse will increase muscle spasm and tension and is therefore harmful, even if proven useful in other patients;
* Immobilization and complete rest (except where necessary due to fracture, etc.);
* Uncontrolled exercise, such as pasture turn-out;
* Any exercise program, including massage or chiropractic manipulation, which has not been approved by the attending veterinarian.
An 18-year-old QH/TB gelding presents with acute right forelimb lameness after being turned out in pasture. The horse has a history of "bone spavin" and has required intra-articular medication in the past. The horse is currently serviceably sound and is used as a basic equitation school horse.
Physical examination and ultrasonography reveal acute tearing of the right fore distal check ligament. There is an associated mild lameness at the walk, and a marked lameness at the trot. The check ligament area is swollen and warm, and pain is evident on local palpation.
The initial recommendation is cold hydrotherapy with gentle range of motion exercises (carpal and distal limb flexion, three slow repetitions only) performed twice daily. Support wraps are applied in the forelimbs, and the horse is confined to a stall. Phenylbutazone is administered (1 gram by mouth twice daily) for five days. Lateromedial radiographs of the foreleg are obtained to evaluate alignment of the bony column, and corrective shoeing is performed to raise the hoof angle using a 2º-wedge pad.
After seven days, there is decreased local swelling and no lameness at the walk. Range of motion exercises are increased and hand walking is instituted. The treatment sequence is:
* Five limb flexions
* Hand walking once around the arena
* Five limb flexions
* Stall confinement
* Leg wraps are maintained in the stall.
The next week, the horse is ridden at the walk, using leg wraps for support. By three weeks following injury, there is no overt lameness at the trot in the right forelimb. However, the gelding is "off" in the hindquarters, presumably from the effects of stall confinement on the chronic tarsal osteoarthritis. Exercise is gradually increased to include riding at the trot.
Two months following injury, the horse is ridden in half-hour basic lessons three times a week. The exercise is limited to walking, a moderate amount of trotting, and very little cantering (once around the arena). By six months after injury, a full lesson schedule is resumed. Jumping and turn-out are not allowed for a full year after the injury.
Physical therapy is important in the management of equine musculoskeletal injury. Principles proven in human medicine are being successfully applied in horses.
The knowledgeable practitioner should be able to write a complete exercise prescription for an equine athlete, and be able to recognize and advise against potentially harmful adjunctive treatments.
Veterinarians should be sufficiently informed to be able to direct physical therapists in patient treatment, and should seek the active involvement of these trained specialists in their practices.
Dr. Kraus-Hansen is a 1995 graduate of Tufts University School of Veterinary Medicine and a 1993 Diplomate of the American College of Veterinary Surgeons. She studied physical therapy with her father, Hans Kraus, MD (deceased), a pioneer in human sports medicine and rehabilitation. She currently operates a general equine and surgical referral practice in Monroe, Wash.