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EQUINE VETERINARY EDUCATION / AE / NOVEMBER 2020
the problem. It appears that valgus angular limb deformities involving the carpus will respond to transphyseal bridge surgery up to 14 months of age, resulting in full correction (Garcia-Lopez 2017; McCarrel 2017). Obviously, if the valgus deformity renders the carpus unstable, then surgery will be required sooner.
Fetlock varus Varus deformities involving the fetlock are common in either the front or hindlimb of newborn foals (Fig 11). This deformity can be congenital or acquired within the first week of life. Fetlock varus is often confused with a foal that has a toe-in conformation. The digit will deviate axially (toward the midline) relative to the fetlock with fetlock varus; a foal with a toe-in conformation will have a rotational deformity at or above the fetlock but the digit will follow the axial alignment of the limb. However, both conditions may occur concurrently. A fetlock varus deformity requires early detection and treatment since functional closure of the distal physis of the third metacarpal/ metatarsal bone is approximately 8 weeks of age. Foals with fetlock varus should have their exercise restricted and will generally respond to an extension applied to the lateral side of the foot to change the forces on the lateral side of the physis. The window of opportunity for treatment is small and the extension should be applied at 1–3 weeks of age. As stated previously, the author is reluctant to apply a composite to a foal’s foot before 3 weeks of age. Alternatively, the author uses a firm impression material (Equilox Pink), moulds it to the solar surface of the foal’s foot forming an extension on the lateral side (Fig 12). The impression material is moulded into the concavity of the sole and the sulci of the frog which holds it in place; it is then secured by covering the foot with kling gauze and then taping the extension in place with 2-inch elastic tape. Between 3–6 weeks of age, a composite extension can be applied to the lateral wall as described above; however,
Fig 12: Impression material is formed to match the concavity of the sole and hold it in place. Impression material can be trimmed
to the desired width of the lateral extension (red arrow). [Colour figure can be viewed at
wileyonlinelibrary.com]
the results are better if correction is started shortly after birth. In severe cases, surgical intervention will be necessary combined with a lateral extension. If the foal is presented for treatment after 6 weeks of age, treatment becomes difficult and surgery will be necessary for correction with the overall treatment being less effective and not as cosmetic. Many fetlock varus deformities are not evident until 8–10 weeks or even later and obviously not addressed until that time. With the exception of a severe fetlock varus deformity; it may be ill-advised to place a transphyseal screw at less than 6 weeks of age because of rapid correction at this early age which necessitates early removal of the implant (R. Hunt, personal communication, 2018). Carpal varus deviations are also recognised in young foals
and weanlings. Foals that develop carpal varus from birth to 1–2 months of age often have an ‘over at the knee’ appearance and buckle forward when standing. These foals typically worsen with exercise and improve with rest. Dietary control is important as is the judicious use of analgesics and controlled exercise. Lateral extensions placed on the foot may be useful but surgical intervention may be necessary if the varus deformity is severe. Weanlings that develop carpal varus are typically offset at the carpus, sometimes pigeon toed and often have accompanying physeal dysplasia. If the physeal dysplasia is kept under control; the deviation will often resolve. If the condition fails to respond, surgery such as transphyseal bridging or placement of a transphyseal screw in the physis of the distal lateral radius may be necessary. In general, valgus deviations are far easier to manage and are more prone to spontaneously correct and appear much more forgiving from a soundness standpoint than varus deviations.
Conclusions
Fig 11: Left forelimb fetlock varus in a 2-week-old foal. Note the varus deformity combined with the toe-in conformation of the digit. [Colour figure can be viewed at
wileyonlinelibrary.com]
© 2019 EVJ Ltd
The concept of protecting the foot from the deleterious effects of mal-loading created by many FLDs and ALDs is just as important as using the symptomatology as an instrument to correct the deformity. Flexural and angular limb deformities are often controversial and have a multitude of purported treatments; it is therefore essential that appropriate communication occur among the responsible parties to avoid any misunderstanding and unnecessary or job threatening miscommunications. Management of limb deformities in foals, irrespective of the type, severity or origin, are best managed through a coordinated effort between the owner, farm manager, farrier and veterinarian. When treating valgus and varus limb deformities especially fetlock varus, prompt early recognition and treatment is best for
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