Contracted tendons are a common problem in newborn foals. In mild cases, the problem will often resolve on its own in a short period of time. In more severe cases, intervention and therapy may be required. One such therapy Veterinarians can apply is the use of an intravenous antibiotic called oxytetracycline.
Contracted tendons are a congenital flexural deformity that occur when the foal’s tendons are too tight or too short for the foal’s legs. All horses have two major tendons that run directly behind their cannon bone (the large bone between the horse’s knee and fetlock). They are appropriately named the superficial and the deep digital flexor tendon. Because the deep tendon attaches to a bone inside the horse’s hoof, if it is contracted or shortened, it causes the foal’s leg to curl up beneath itself–which is exactly what happens in a case of contracted tendons.
The prognosis for newborn foals with contracted tendons is good. In moderate cases, Veterinarians can correct the deformity in many ways, such as prescribing controlled periods of exercise and rest or, in some cases, the use of aids like special shoes with toe extensions or leg splints. All foals with contracted tendons should be monitored closely to ensure their reduced mobility does not hinder efforts to stand, nurse, and consume adequate nutrition and hydration.
In severe cases, the foal will have a great deal of difficulty standing, walking, and nursing unaided. These cases require round-the-clock care and may benefit from oxytetracycline treatment. The viability of treating a condition like contracted tendons with an antibiotic may sound odd, but it has been used with much success in horses, often with rapid results. Research has shown oxytetracycline prevents the influx of calcium ions into the muscle fibers, which allows the tendon to relax. It is important that the renal function of the foal be monitored during oxytetracycline treatment, as this drug has the potential to induce acute renal failure, particularly in a dehydrated foal.
Protocols for Foals with Contracted Tendons. J. Brett Woodie, DVM, MS, DACVS. May 5, 2017
Oxytetracycline Inhibits MMP-1 MRNA Expression and Collagen Remodeling by Equine Tendon Myofibroblasts In A Dose-Dependent Manner: A Mechanistic Basis for The Pharmacologic Treatment of Equine Flexural Deformities. Michigan State University. May 2004.