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Contracted Tendons & "Tippy Toed" Foals 13 December, 2011
- Dr Sarah Seitz
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If you see your mare's newborn foal prancing around the stall like it is wearing invisible high heels, you might be a little concerned that your foal is dreaming of being a ballerina instead of a racehorse. Don't worry; one of the most common deformities that equine veterinarians deal with in newborns is contracted digital flexor tendons. This sometimes causes foals to walk on the toes of their front hooves instead of being flat footed.
It is uncertain why this malformation occurs, but there are several speculations. One theory is that the foal might be relatively large before birth resulting in intrauterine malpositioning which inhibits the proper development of the digital flexor tendons. Other reasons might be ingestion of locoweed and hybrid Sudan grass during pregnancy, goiter, or a dominant gene mutation in the sire.
Regardless of the cause, the end result is a tendon that is too tight or too short for the foal's legs. Anatomically speaking, horses have two major tendons that run directly behind their cannon bone. They are appropriately named the superficial digital flexor tendon and the deep digital flexor tendon. The deep digital flexor tendon attaches to the coffin bone (the bone inside the horse's hoof), so if it were to be contracted or shortened, it would cause the horse's leg to curl up beneath itself, which is what happens in a case of contracted tendons.
Veterinarians can correct the deformity in many ways, but each case requires individualized treatment. Generally, the prognosis for a foal born with contracted tendons is good. While some minor cases might not need any treatment, more severe deformities require intervention.
One of the treatment options veterinarians can try is an intravenous antibiotic (oxytetracycline). It might seem odd to use to use an antibiotic for a problem such as this, but it is thought that oxytetracycline prevents the influx of calcium ions into the muscle and tendon fibers resulting in relaxation. And relaxation is exactly what the doctor calls for if tendons are pulled so tightly that the hoof cannot touch the ground appropriately. Only use this treatment method under direct supervision by your veterinarian because oxytetracycline has several know undesirable side effects in foals if used incorrectly.
Conservative or non-surgical methods of treatment such as dietary modification, exercise, anti-inflammatories and corrective hoof trimming and shoeing are appropriate for milder deformities that have been detected early. Dietary restriction is aimed at reducing the energy intake and therefore slowing the growth of the foal. Weaning early, when a foal is
still nursing, may be useful.
In cases of coffin joint flexural deformity, simply trimming off the excess heel of the hoof alone is not recommended. The club foot develops due to excessive wear at the toe and lack of wear at the heel, so gradual trimming should be combined with a toe extension. This protects the toe from wear and helps to put more force on the tendons, which assists in their lengthening. It is also helpful for the foals to have a moderate amount of exercise to help put more tension on the tendons. This stretching of the tendons can be painful, creating a unwillingness to exercise, so some foals may need medications for pain relief.
For more severe deformities of the coffin joint, or where conservative treatments have failed, surgical intervention may be required. The treatment of choice for less severe deformities is to cut the accessory ligament of the deep digital flexor tendon (DDFT).
Splints combined with controlled exercise may be beneficial for foals with mild and/or early deformities of the knee. Surgical intervention involves the cutting of two tendons at the back of the knee. This procedure has been successful with a good prognosis for those foals with milder forms of this deformity.
Regardless of the location and tendons involved, in all forms of flexural deformities the severity and longer term complications that may arise are associated with a poorer prognosis and may require more invasive surgical procedures. Therefore it is important to regularly look at growing foals to recognize these problems as early as possible.
 Sarah Seitz was born in Zimbabwe and moved to South Africa when she was 10 years old. After attending high school at St Andrew's in Johannesburg, she worked for her father for several years doing wildlife conservation and breeding endangered species. After that, she was introduced to the illustrious world of thoroughbred breeding and racing when she was employed to manage a thoroughbred stud farm for four years. This stud has produced several notable winners in its time, including a Durban July winner.
She found herself really enjoying the veterinary aspect of equine management and breeding, so decided to come the USA to study Veterinary Medicine. Far from home and lots of paperwork later, she completed her undergraduate BSc degree at the University of Kentucky in Lexington, and she is currently in her final year of Veterinary Medicine at Washington State University in Pullman, Washington. Sarah's primary veterinary interest is large animal medicine and theriogenology. Sarah also enjoys volunteer work and has traveled to several countries including India, Nicaragua and Ecuador to provide free veterinary services to underdeveloped communities. |
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