EQUINE VETERINARY EDUCATION / AE / NOVEMBER 2020
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2000; Greet and Curtis 2003; Auer 2006; Witte and Hunt 2009; Garcia-Lopez 2017; O’Grady 2017). This subject receives tremendous attention in any discussion of foal conformation and it refers to a lateral or medial deviation in axial alignment of the limbs when the animal is viewed from the frontal plane. It is understood that a certain amount of deviation can be normal in young foals and does not require any special farriery or surgical intervention (Hunt 1998, 2000; Auer 2012; O’Grady 2017). Objective data is lacking regarding the dynamics involved in the development of acquired angular limb deformities, however, it is recognised that many foals change axial alignment during various stages of their development. Serial evaluation and treatment of limb deviations is an integral component of management on most breeding operations. Angular limb deformities may occur anytime during the
Fig 6: Reverse wedge created from a composite. An aluminium plate can be imbedded in the composite to prevent wear.
The surgical aftercare is at the discretion of the attending
clinician. Oxytetracycline may be used with the surgery during the perioperative period to facilitate relaxation of other soft tissue structures secondarily involved (joint capsule, collateral ligaments) (Hunt 2012). Controlled exercise in the form of daily walking or turn out in a small paddock with firm footing such as a round pen is essential. There is the potential for pain with the initiation of exercise due to the shortening of soft tissue structures such as the joint capsule and suspensory ligaments to the navicular bone, requiring close monitoring of the foal, and exercise should be increased sequentially. The foal is trimmed at roughly 2-week intervals, based on the amount of hoof growth at the heels with the objective of establishing normal hoof capsule conformation. The composite wedge is removed one-month post-surgery. At subsequent trimmings, the heels are trimmed as necessary from the middle of the foot palmarly such that the frog and hoof wall are on the same plane and hoof wall at the toe is trimmed from the dorsal aspect of the hoof wall until the desired conformation is attained. No sole dorsal to the frog is removed. This type of trim promotes sole growth and creates approximate proportions on either side of the COR. When the desired foot conformation is reached, the foot is trimmed in a routine manner monthly. It is important to emphasise that when the hoof capsule returns to an acceptable conformation, only that portion of the sole that is shedding should be removed. This avoids causing discomfort in the dorsal solar section of the foot that can result in the foal redeveloping, to some degree, the original flexural deformity. The higher-grade clubfoot appears to have a tendency to revert back to the original deformity if not managed properly.
Angular limb deformities
Angular limb deformities (ALD) are common in foals and require early recognition and treatment (Greet 2000; Hunt
Fig 7: Carpal valgus. Note the limb below the carpus deviates away from the midline (red line).
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animal’s life but are most commonly treated from birth through the yearling growth period. The primary lesion appears to be an imbalance of physeal growth; for assorted reasons, growth proceeds faster on one side of the physis vs. the other. Although this is described as a discrepancy of limb length of the medial vs. lateral side from an imbalance of physeal growth; another discrepancy in loading the limb with lack of soft tissue support may also create an ‘apparent’ ALD. Angular limb deformities can be further classified into two categories; valgus deformities occur when the deviation occurs lateral to the axis of the limb distal to the affected joint (away from the midline) and varus deformities occur when the deviation is medial to the axis of the limb distal to the affected joint (toward the midline) (Fig 7). The most common location of valgus angular limb deformities is the carpus and tarsus while varus deformities are most often seen at the fetlock and to a lesser extent at the carpus.
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