Texas Equine Veterinary Association

www.teva-online.org • Page 12 aimed at reducing tension on the DDFT tension apparatus. Theoretically, oxytetracycline produces chelation of calcium ions with the net effect of relaxation of muscle groups. Unfortunately, with clubfoot disorder having a propensity to be accompanied by back of the knee conformation, the drug typically worsens the carpal conformation while having limited effects on the foot. The author routinely administers oxytetracycline in conjunction with performing surgery to enhance relaxation of the muscle unit and relax other involved soft tissues. Other antimicrobials, such as enrofloxacina, clinically produce a similar effect of relaxation of flexor tendons and may have benefit similar to oxytetracycline. Botulinum toxin (Botox) is utilized in people and has been reported for use in horses with laminitis to achieve relaxation of the DDFT to prevent distal phalangeal rotation. The drug may have merit in the management of clubfoot in horses in the future with appropriate application. Clubfoot may develop as yearlings or may be a continuum of the process initiated earlier in life. In general, the older the animal is at the onset, the less likely of obtaining a normally conformed foot, although, this does not necessarily preclude a successful athletic career. If the condition is acquired as a yearling it is almost always secondary to a lameness or gait deficit resulting in inappropriate loading of the foot, such as with a neurogenic disorder. If the primary disorder is rapidly rectified, the foot may return to normal if the gait is restored to normal prior to the development of irreversible changes in the foot. The mechanical principles involved in therapy are the same as for the weanling, and the primary objectives with any of the procedures are to maintain comfort and to obtain a mechanically sound foot. Changes in hoof shape achieved in yearlings (and adults) are often less than those obtained in younger horses. Adult clubfoot disorders may be present due to a previous clubfoot as a juvenile, may be secondary to other lameness, or may result as a sequel to chronic laminitis. The principles of management of club foot in the adult are the same as in other age groups; however, pathologic changes of the foot are often more advanced due to the duration of the deformity. Expectations for a favorable outcome are largely determined by three factors: the severity of the deformity, the integrity of both the hoof capsule and third phalanx, and the intended use of the horse (breeding vs. athlete). Many horses are able to compete athletically with a clubfoot as long as they are maintained on a consistent hoof management program. Mild deformities are managed in large part through routine farriery aimed at trimming for optimal and uniform load bearing of the entire hoof wall. The hoof angle required to achieve this type of load bearing is usually steeper than normal, but is a necessary compromise to avoid lameness associated with either hyperextension of the distal interphalangeal joint and accompanying structures or excessive stress on other soft tissue structures, which often occur secondary to an attempt to establish a normal hoof angle. Breakover may be enhanced in these individuals by rolling or rockering the toe. As in the management of all club feet, the foot must not be allowed to grow to extremes and undergo separation of the wall. The general guiding principle is to trim the foot at an angle which allows full loading of the heels or landing flat footed when ambulating. The heels should not be lowered to the point of allowing toe contact prior to heel contact at the walk. If the hoof wall integrity is poor and the foot undergoes recurrent bruising and abscessation, protection of the wall and sole through shoeing or casting may be necessary. Similar principles apply regarding uniform loading of the wall and enhancing breakover to reduce shear forces along the dorsal laminae, as in milder cases of club foot. Adult breeding horses with a clubfoot are subject to excessive trauma at the toe and subsequently are prone to develop subsolar abscessation and eventual pedal osteitis. Extra measures in these horses may be useful, such as shoeing to protect the toe. In protracted, severe cases of club foot deformity with advanced pedal osteitis, desmotomy of the accessory ligament of the DDFT or DDF tenotomy may be beneficial. Desmotomy of the accessory ligament of the DDFT is usually reserved for less severe cases of club foot deformity in which the individual is intended for athletic endeavors. Clinical experience has yielded favorable results from these procedures in the form of improved integrity of the wall, expansion of the hoof capsule and an angle that is closer to normal in addition to a reduction of hoof abscessation. If the decision is made to perform a deep digital flexor tenotomy, although improvement is usually achieved whether the tenotomy is performed mid- metacarpal or mid-pastern, clinical impression is that the mid-pastern tenotomy produces more relaxation of the tendon and therefore more de-rotation of the distal phalanx. sUrgicaL ProcedUres The underlying premise supporting surgery for treatment of club foot is to relieve the rigid tension band of the DDFT extending from the third metacarpus via the accessory ligament of the DDFT to insert on the distal phalanx. The two methods of accomplishing this include transection of the accessory ligament of the DDFT and transection of the DDFT. Several techniques have been described to accomplish each procedure. Transection of the accessory ligament of the DDFT has been described using conventional surgical dissection from a lateral or medial approach, using ultrasound guidance, using tenoscopic guidance and performing the surgery in lateral or dorsal recumbency, or standing. Each technique has advantages and disadvantages; the main disadvantage all techniques attempt to avoid is the cosmetic blemish associated with the surgery. I do not believe there is a difference in cosmetic outcome with one technique over another provided the surgery is performed proficiently and

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