Texas Equine Veterinary Association

www.teva-online.org • Page 10 the more common form occurs along with, and is likely secondary, to bilateral flexural deformity of the knee and fetlock joints. The etiology for this deformity is generally undetermined but factors incriminated include genetics, intrauterine malposition, teratogens, influenza virus exposure, or sudan grass ingestion. Evaluation of the foal includes observation of the stance of the foal and the ability of the foal to ambulate. Foals which exhibit bilateral carpal flexural deformity with clubfeet require minimal to no intervention if they have the ability to stand, ambulate and nurse unassisted. Manual extension of the lower limb almost always produces a normal angle and alignment of the distal interphalangeal joint. Management is conservative and resolution of the clubfoot resolves with correction of the primary deformity. Treatments for carpal and fetlock contractures include physical manipulation and stretching of the legs in conjunction with a variety of forms of external coaptation aimed at fatiguing the musculotendinous unit. Bandaging, transient static splinting with PVC bracing or dynamic splinting with an articulating brace, application of a flexible tension band along the dorsal aspect of the limb, and casting are accepted techniques when properly applied and managed. Application of a cast in a mildly extended position in the first hour after birth will often improve the condition enough to allow splinting or bandaging until the condition fully resolves. Administration of oxytetracycline (44 mg/kg IV, SID) will also facilitate improvement of the deformity. The less common variation of clubfoot in neonates occurs as an isolated unilateral deformity of the distal interphalangeal joint and does not correct with manual extension applied to the joint. The deformity occurs in all degrees but is often severe and difficult to manage. Contrary to common practice, toe extensions are not beneficial and typically cause the foal to stumble. Although it is difficult to apply useful external coaptation to this area, articulating extension braces attached to a foot cuff, application of a cast, or application of a flexible tension band with surgical tubing will provide appropriate mechanics to this area. Oxytetracycline is a beneficial treatment, however, typically results in excessive laxity of the normal regions such as the carpi and fetlocks. In extreme situations surgical resection of the accessory ligament of the deep digital flexor tendon or transection of the deep digital flexor tendon is necessary. Although the author is unaware of any recognized, specific guidelines for surgical intervention in the neonate, with a primary unilateral clubfoot in which the hoof angle is approaching or exceeding 90° and no improvement is seen with conservative treatment within two weeks, surgery should be considered. The most frequently recognized form of clubfoot in horses occurs in sucklings or weanlings at approximately two to eight months of age. It is commonly a unilateral condition but occasionally affects both limbs. The first clinical sign recognized is an upright appearance of the foot combined with the inability of the heels to contact the ground immediately after trimming the foot. As the condition progresses the coronary band develops a square or full appearance dorsally. As the toe wears, the upright nature of the foot becomes more evident and the foot assumes a contracted shape losing its flare as it grows distally. The dorsal hoof wall begins to dish and widens at the white line. Concurrently, the carpus often assumes a back of the knee conformation. The toe may become bruised and ultimately abscess, resulting in severe lameness. Because of the abnormal forces on the distal phalanx and inflammation associated with excessive loading, bruising, and abscessation, pedal osteitis is a common occurrence. Differentiation should be made between a developing club foot and a foot which is upright from excessive wear at the toe. The latter is a self-limiting problem as long as lameness is not severe and abscessation is not present. If lameness is present a protective device over the toe will generally alleviate the problem once the foot grows sufficiently. A foot of this type responds well to most treatments and undue credit is often given to aggressive therapy which was unnecessary in the first place. Clinical management of clubfoot is influenced by the severity, duration, and the etiology of the clubfoot as well as the degree and source of lameness, if present. Evaluation of the foot should be performed at rest and in motion. The angle and balance of the foot should be determined and the foot should be inspected for under-run or separated wall or sole. Sensitivity to hoof testers or response to firm pressure from fingers should be assessed. If lameness is present, peripheral nerve blocks should be performed in order to isolate the origin of the lameness. Radiographs of the foot should be taken to assess the position and the integrity of the distal phalanx, or presence of other pathology. If there is evidence of pedal osteitis, especially in the presence of a severe club foot, venographic evaluation may aid in prognostication. If the clubfoot is secondary to lameness of other origin it is imperative to isolate and resolve the other lameness prior to attempting therapy for the clubfoot. Treatment in the early stages of a developing clubfoot involves establishing a normal hoof angle by lowering and spreading the heels as long as the foal remains sound. It is imperative to establish soundness and maintain normal load bearing throughout treatment. One should adhere to the guidelines for trimming and providing a sound, balanced foot. The bars should be removed to decrease as much restrictive mass of the hoof capsule as possible and the frog should be trimmed to healthy compliant tissue to enhance loading. The wall through the quarters and heels should be lowered to the plane of the frog and parallel the frog. If the toe is worn excessively a protective device applied to the toe in order to prevent bruising and subsequent lameness may be applied. The toe may be rounded or beveled to promote break-over and alleviate any lever effect of the toe as well as to reduce stress on the lamella. Severe clubfoot is usually complicated with contracture of soft tissues surrounding the distal interphalangeal joint, including the joint capsule and presumably the collateral ligaments or other supportive structures in the region. Therefore, there are inherent limitations on effectiveness of corrective procedures. Alleviating tension of the deep digital flexor tendon by transection of the DDFT accessory ligament or transection of the DDFT may not yield a normal angle of the hoof and may also not produce soundness, although it is unusual not to obtain some degree of improvement with surgery. Other alternative modalities of therapy to consider include the use of oxytetracycline 13 (44 mg/kg, IV, SID)or other medications

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