Treatment of equine lameness
The end goal is to reduce the pain and inflammation associated with injury, to encourage the injured tissue to heal with normal structure and function, and to ultimately return the horse to the highest possible post-recovery performance.
[5] Certain treatments may improve the final tendon fiber quality, and subsequently increase the likelihood that the horse will return to full performance post-injury.
[6] Rest is almost always recommended for treatment of lameness because it reduces forces placed on damaged tissue, allowing the normal process of healing to occur.
Animals with a history of upward fixation of the patella,[8] polysaccharide storage myopathy,[9] and equine recurrent rhabdomyolysis are often best kept on a schedule of regular exercise.
[11][12] Horses that undergo long-term stall rest require a slow, progressive rehabilitation program to try to prevent re-injury of the original tissue or injury to a new area now weakened by prolonged disuse.
The goal is to reduce strain or load on structures that are at-risk of damage secondary to conformation, movement, or past injury, or to treat areas that are healing and can no longer handle normal forces.
Application of various types of therapeutic shoes, pads, and wedges, can be used to help alter stress placed on structures within the foot or the lower limb.
[35] However, there is much anecdotal evidence of their benefits for synovitis and osteoarthritis, and PSGAGs are very commonly used by veterinarians in the United States involved in racehorse and show horse practice.
In osteochondral fragmentation models, intravenous HA has been shown to decrease lameness, improve the synovial membrane, and lower protein and prostaglandin E2 levels within joints.
In non-equine models, Pentosan has been shown to increase proteoglycan synthesis,[40] stimulate hyaluronic acid production in osteoarthritic joints (a benefit not shared by PSGAGs),[41] reduce inflammatory cytokines, and improve damaged articular cartilage.
Some practitioners chose to use methylprednisone to treat low-motion joints, especially of the distal hock, for the sole purpose of destroying the cartilage and reducing the time to natural ankylosis.
Its use is regulated by many equine competitive governing bodies, since it is thought to have a CNS depressant effect and produces the metabolite guaifenesin, which is a pre-anesthetic veterinary drug.
Additionally, autologous stem cells (those harvested from the patient) requires 2–3 weeks to expand the numbers in culture, delaying treatment of an acute injury.
Allogenic (non-self) stem cells may be harvested from other horses ahead of time to have banked for immediate treatment of an injury, but there is some concerns of graft-vs-host disease.
Horses with tendonitis treated with bone marrow derived stem cells had a significantly lower re-injury rate compared to those without treatment.
These growth factors lead to new blood vessel formation, inflammatory cell infiltration, and the generation of connective tissue, which should ultimately improve the speed and quality of healing.
[7] Interleukin 1 receptor antagonist protein (IL-1Ra, or IRAP) inhibits IL-1, and has been shown to reduce the disease process, including improvement in lameness and histological morphology of cartilage and synovium.
ESWT is commonly used for treating orthopedic problems in horses, including tendon and ligament injuries, kissing spine, navicular syndrome, and arthritis.
[104] Higher depths can increase pelvic flexion and raising of the back, helping to strengthen muscles that are commonly used by riding horses, conditioning them without the added weight of a rider.
[110][111] Approved uses for HBOT in humans include clostridial myositis, crush injury, carbon monoxide poisoning, compartment syndrome, treatment for chronic wounds, osteomyelitis and abscesses, skin flaps or grafts, and burns.
The procedure has been shown to have good results in cases of chronic proximal suspensory desmitis of the hind limb (78% success rate), assuming the horse has no other musculoskeletal problems.
It is used as a salvaging procedure to save the horse with an injury that disrupts the stability of a joint, such as septic arthritis, failure of the suspensory apparatus, subluxation, fracture, or collateral ligament rupture, or may be used to treat chronic osteoarthritis.
A horse will not be athletically useful following a DDFT tenotomy, with a best-case scenario of the animal returning to pasture soundness or possibly for comfortable enough for light pleasure riding.
A DDFT tenotomy can also be used to treat severe cases of flexural limb deformity in foals, but it is also a salvage procedure and prevents the animal from any future athletic use.
Contracture of the DDF forces the limb to maintain a constant flexed position in the fetlock and coffin joints, and if not corrected can be devastating to the athletic potential of an animal.
Check ligament desmotomy is considered superior to a deep digital flexor tenotomy because the animal has reduced pain and a greater chance of returning to full function following surgery.
In racehorses with moderate to severe tendinitis of the SDFT, 69% returned to racing following a superior check ligament desmotomy, and were able to do so faster than horses that had not undergone the procedure.
Thermocautery (pin firing) has been declared “unethical” by the Royal College of Veterinary Surgeons, although it is considered an acceptable therapy by the American Association of Equine Practitioners “when applied judiciously and in conjunction with appropriate analgesia and aftercare… in cases that have proven refractory to conventional treatment.”[133] Blistering agents are chemical substances used to irritate tissues, leading to inflammation, increased circulation, necrosis, and scarring.
The contralateral (opposite) leg then bears all of the weight, which reduces blood flow to the hoof and strains the attachments of the laminae, leading to laminitis.
In cases of severe unilateral lameness, aggressive pain management using a combination of drugs in various classes such as opioids, alpha-2 agonists, ketamine, topical NSAIDs, and local anesthetics should be considered.
