“… there is a limited window of time to change the growth pattern of bone and … there are many options to consider depending on location and severity.”
the epiphysis. Eventually the diaphysis and the epiphysis will ossify and join together resulting in closure of the growth plate. As long as the physis is open, correction can be made to the bone growth, but once the physis is closed, the bone can no longer be influenced. “The window of opportunity is finite,” warns John Peloso, DVM, MS, Diplomate ACVS, when discussing the surgical treatment of ALD. “Growth has to occur in order for it to be manipulated.” So how long do you have? The fetlock physis will be the first to close, between four and six months. Any correction would need to be done before the foal reaches four months of age. Knees and hocks will grow up to 24 months but initial treatment is recommended between eight to twelve months.
Evaluating Treatment Options In situations when an ALD is not severe, doing nothing is the best way to go. In other words, allowing nature to take care of the problem is the ideal. Carolin von Rosenberg, DVM, who specializes in equine reproduction, says, “If the angle is slowly correcting itself and the leg is growing in the right direction, then keep watching and waiting because most of the time foals will self-correct as they grow.” She believes the best way to determine progress is to evaluate your foal every two weeks by documenting the foal’s legs with photographs and even videos. There are several treatment options to consider for both minor and severe cases of ALD. Before you make a decision, your foal should be evaluated by a veterinarian or an equine professional that you trust who has experience in assessing foal conformation. Treatment should be decided based on the location and severity of the angulation. In some cases, surgery is recommended, while non-surgical options include exercise restriction, stall rest, splints or casts, corrective trimming or glue-on shoes. Keep in mind that a slight valgus deviation will correct itself as the foal grows. Outward rotation of the elbow and inward rotation of the toe happens as the foal’s strength increases, his chest fills out and the connecting muscles become stronger. A non-surgical option for correcting some ALD cases is
a product called a Dynasplint made by Dynasplint Systems, Inc. It can treat both varus and valgus deviations as well as support dominant, weight-bearing limbs. It can also be used on foals to support incomplete ossification of cuboidal bones and foals with significant tendon laxity. Originally designed to treat equine contractures, the Dynasplint has also been known to improve an ALD. The Dynasplint is a specially designed equine splint that can be used on a daily basis, for six to eight hours a day, to shorten and lengthen the soft, connective tissue around the
56 July/August 2013
Left: A two-week-old foal with an 18-degree deviation. Right: Same foal after using the Dynasplint for six weeks, six hours per day.
bone. It encourages the bone to align more properly but does not change the bone itself. Following the principle of Wolff’s Law, which states that bone in a healthy person or animal will adapt to the loads under which it is placed, the idea is that the bone will remodel itself over time in order to adapt to the load placed on it. This is a corrective option that has less chance of infection, does not require anesthesia and reduces stall-rest time. The splint application works well for tendon laxity in foals because the support is soft-tissue oriented. It can also support the joints of premature foals long enough for the bone and tissue to properly develop, preventing damage to the cuboidal bones. The concept is to provide a low-load prolonged duration stretch (LLPS) technology that delivers a biomechanically correct stimulus to shortened connective tissue. In other words, by using very low tension over a long period of time, the tendons will stretch to create proper bone alignment. The need for proper application and monitoring for
pressure sores is important since in rare cases these sores can develop. There is a learning curve when applying a Dynasplint. Average fitting time for a splint is five to ten minutes, claims the manufacturer, depending on the type of bandage that might be required beneath the splint.
The Surgical Option Varus deformities or deformities that are too severe to correct on its own may also lead to secondary deformities and surgical treatment should be considered. In these cases, surgeons will insert a screw into fetlocks and hocks or insert screws and wires for knees. Hardware is inserted in the part of the bone where growth needs to be retarded, allowing for the opposite side of the bone to catch up as it continues to grow. In most circumstances, surgery will remedy an ALD if
the procedure is done correctly, within the proper time frame, and the foal is monitored weekly after the hardware is inserted. Post-surgical treatment is fairly uniform—
Courtesy Dynasplint
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