mare and foal in field

Flexural Limb Deformity

What is flexural limb deformity?

Flexural limb deformity occurs in two forms. 

The first form, also known as contracted tendons, clubfoot, or knuckling, is the inability to extend a limb fully. The condition may be present at birth (congenital) due to improper positioning in the uterus (which can lead to dystocia in the mare), abnormal fetal development, disease or malnutrition in the dam, or acquired as the result of nutrition (abrupt changes in amount or quality of feed leading to rapid growth), polyarthritis, trauma, or disease. It is a common condition in foals, usually occurring anytime from birth to 14 months of age.

The second form is known as laxity, and occurs most commonly in newborn foals.  It is also due to congenital, and possibly hereditary, causes. 

What are the clinical signs of flexural limb deformity?

Clinical signs of contracture in foals can include knuckling over of the fetlock or knee, trembling of the joints, walking on the toes with the heels off the ground, and inability to completely straighten the limb for normal weight bearing. Severely affected foals are unable to stand. Hooves may appear upright with long heels and concave toes, known as a “club foot” in the most severe form.

Clinical signs of laxity include back-at-the-knee conformation, dropped fetlocks, inability to stand, difficulty walking, or walking on the heels with the toes up in the air. In most cases, both left and right limbs are affected, with one worse than the other.

How is flexural limb deformity diagnosed?

Diagnosis of flexural limb deformity is based on physical examination and visual assessment. Radiographs (x-rays) and other imaging modalities may aid in diagnosis.

How is flexural limb deformity treated?

Treatment for flexural limb deformity with contracted tendons can include bandaging, splinting, physical therapy and limited exercise (large foaling stall access only). Therapeutic trimming and shoeing may be used to support correct conformation. Pharmacologic treatments, such as oxytetracycline, may be used to allow musculoskeletal relaxation and tissue elongation. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be administered when deemed appropriate to reduce inflammation and relieve pain. Surgical intervention may be warranted in chronic or very severe cases.

The laxity form is treated with controlled exercise, initially consisting of hand-walking twice daily.  As limbs improve and the laxity improves, exercise is gradually increased.  Shoes with heel extensions are often used.  These often include tape-on or glue-on shoes.

What is the prognosis for flexural limb deformity?

Early recognition and accurate diagnosis are optimal for timely treatment. Treatment is often successful and recurrence is uncommon. Cases that do not respond well to treatment have a poor prognosis for long-term soundness and athleticism.

How can flexural limb deformity be prevented?

Mares should receive well-balanced nutrition during pregnancy to facilitate the birth of healthy foals, including balanced macro- and microminerals, and avoidance of excessive simple sugars and starch (i.e. grains). Foals should be closely monitored after birth to ensure proper development. Extremes in diet (especially excessive starch, sugar, and calories in general), as well as exercise, should be avoided. Contact a veterinarian as soon as an abnormality is suspected to ensure timely treatment.

For more information:

Gaughan, E.M. 2017. Flexural Limb Deformities of the Carpus and Fetlock in Foals. Veterinary Clinics of North America: Equine Practice 33(2); 331-342.

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