Angular Limb Deformity in Horses

Almost all foals are born with some form of angular limb deformity (ALD), however most grow out of the deformity by 4 weeks without treatment. Uncommonly, foals continue to have unusual leg conformation beyond 4 weeks. These foals require prompt veterinary intervention to begin treatment before the growth plates close, as treatment thereafter becomes more challenging.

Foals with ALD often develop secondary complications due to the irregular conformation of their limbs. In some cases, the hoof shape may be altered by excessive wearing on one side of the hoof as the foal moves, due to uneven weight bearing. In addition, ALD can be associated with incomplete development of the bones in the knee or hock, and the uneven weight bearing from ALD may cause permanent damage to the developing bones.

In some cases, foals with ALD may have damage to their growth plates.

There are many potential factors contributing to ALD in foals. Most cases of ALD are present at birth, but some may develop over time due to abnormal growth rates in the bones. Factors increasing the risk of ALD include:

• Being born premature or dysmature
• Laxity of the tendons
• Traumatic injury to soft tissues or to the bones
• Malpositioning in the uterus before birth
• Unbalanced nutrition
• Rapid growth
• Excessive exercise causing overloading of the limb

The main symptom of ALD is unusual leg conformation in a newborn or growing foal. ALD may appear as:

• “Toed out” or “toed in”/”pigeon toed” feet
• Deviation of the limb inwards or outwards when the foal is viewed from the front or behind

Diagnosis of ALD is self-evident based on physical examination, however, veterinarians often require further diagnostics to determine whether there are underlying problems that need to be addressed. Additional tests may include:

• Lameness examination
• Diagnostic imaging of the limbs and joints that may be affected and evaluate the growth plates

The goal of treatment is to straighten the limb to prevent further damage. Treatment may involve a combination of:

• Stall rest
• Splinting or casting
• Corrective shoeing or trimming
• Dietary adjustments
• Surgical intervention to alter the growth of the bones
• Anti-inflammatories

The prognosis of ALD depends on the severity, the promptness of treatment, and the type of treatment used. If caught early, before the growth plates have closed, many mild cases can have their legs corrected with casting or corrective shoeing alone. In more severe cases or cases where the growth plates have closed, surgical intervention is required. Foals undergoing surgical intervention are still able to have athletic careers as adults if managed appropriately during the postoperative period. Foals that develop lameness or have damage to the bones in the hocks or knees have the poorest prognosis, and may be unable to have an athletic career.

There are no proven methods for preventing ALD, however providing balanced nutrition to growing foals and pregnant mares may play a role in reducing the risk of disease.

ALD is common in foals, however most grow out of the deformity without treatment by 4 weeks. Continued deformity after 4 weeks is uncommon.

• Stall rest
• Splinting or casting
• Corrective shoeing or trimming
• Dietary adjustments
• Surgical intervention
• Anti-inflammatories