A team of British researchers has recently completed a study evaluating the success rates of a novel technique they developed to treat congenital flexural deformities in young foals, with promising results.
Flexural deformities occur when the soft tissue structures in foals' legs are disfigured causing one or more joints to be "stuck" in the flexed position; often, more than one limb is involved in affected foals. Mild cases often resolve with exercise alone or in combination with customized splints and/or casts, toe extensions, and/or intravenous oxytetracycline (which has been shown to relax tendons and ligaments). More severe cases, however, can keep the foal from standing and typically necessitate surgical intervention—which carries a high price tag and risks associated with general anesthesia—to correct the deformity. Lower limb deformities (such as those involving the fetlock and coffin joints) are more easily corrected and carry a better prognosis for recovery than deformities located higher in the leg (such as knee deformities).
Polly Compston, BSc, BVM&S, MRCVS, a resident in clinical research, and Richard Payne, BSc, BVSc, CertES, Dipl. ECVS, MRCVS, a surgeon and partner at Rossdales Equine Hospital in Newmarket, England, recently evaluated a novel technique for treating congenital flexural deformities (those present from birth) in foals' lower limbs that they believe can save time, money, and possibly even a trip to the hospital.
Compston and Payne described the technique in the study: "We make a cast for the leg that is not affected by the deformity as a template for how the affected limb should be. The cast is then split into two to make a splint and bandaged onto the front of the affected limb with lots of padding underneath it. We then place a wire from the bottom of this splint through the toe of the foal’s hoof. This wire is then tightened to help straighten the leg, creating ‘active extension’ on the flexural deformity. This means that even when the foal is lying down there is pressure on that joint that helps it to straighten”
Compston and Payne treated 13 foals with congenital flexural deformities of the lower limb with their new technique. Of those foals, six required one splint, six required two splints, and one required three splints. The coffin joint was most commonly affected (72% of affected limbs), they relayed, and front limbs were affected 76% of the time. Additionally, two foals had concurrent carpal deformities, they said.
Once the splints were applied, foals remained stabled. The majority of the splints were removed after three days, at which point the flexural deformities were reevaluated. If the deformity warranted further correction, the team applied a new splint. If the deformities had improved to the team's satisfaction, the foals remained inside for 24 hours before gradually returning to their normal management routine.
Upon reviewing their data and long term follow-up information, the team found:
- Eight foals had recovered well from their flexural deformities; "All were sound and being used for their intended purpose," Compston said. "Overall the level of satisfaction from the clients' points of view was very high."
- "Two (of the 13 treated) foals had reports of splint-related problems (swelling and bandage sores) that resolved with time and appropriate management," Compston said. "When owners were questioned about post operative complications that had not been severe enough to require veterinary attention, four reported white hairs and one reported a small fibrotic lump, both resulting from pressure on the dorsal cannon."
- Compston noted that one foal developed coffin bone septic osteitis (inflammation of bone beginning in the periosteum, or membrane surrounding bone) 43 days after casting. "This was assumed to be due to laminar penetration by the toe wire," she said. "The infected foot was debrided under general anesthesia and the foal fully recovered."
- Compston noted that four foals—including the two with carpal deformities—were euthanized before two years of age: two due to the carpal deformities, one due to an unrelated orthopedic disease, and one due to a trailer accident.
Compston said that while the results of the current study are "encouraging with respect to the success fate of this novel technique," she suggested that "foals should be monitored carefully during the immediate post-operative period, after which ongoing review for any unexpected lameness or foot sensitivity should be advised to allow for the detection of any problems.
"Owners should also be warned about the risk of scarring and white hair formation, which may be more common than with conventional splinting due to the pressure on the dorsal cannon bone created by the active tension technique," she continued. "However in this series, these problems were considered cosmetic and did not result in any functional deficit."
Compston said that further studies are needed to determine the "maximum angle of flexion" that can be successfully resolve using this technique.
"This is a technique that could be easily carried out in the field and therefore incorporated into the equine general practitioner's repertoire," she concluded.
The study, "Active tension-extension splints: A novel technique for management of congenital flexural deformities affecting the distal limb in the foal," appeared in July 2012 in Equine Veterinary Education. The abstract is available online.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.