Limb Deformities in the Foal

Written and presented July 2006 by R.F. (Ric) Redden, DVM

Introduction Limb deformities are commonly found in new foals. They can be congenital or developmental and with varying degrees of deformity ranging from mild to severe. The majority of deformations will fall into one of five basic categories.

1. Angular - Angular deformities occur when the distal extremities of the limb deviate from the midline of the limb. Valgus deformity is a deviation lateral of the mid line. Varus deformity is a deviation medial of the mid line.

2. Axial - Axial deformities can be described as a medial or lateral shift at the anterior articulation, e.g. offset knees.

3. Rotational - Rotational deformities are muscular in origin and most commonly involve the front limbs. The limb itself may have acceptable alignment, but rotates outward due to muscle attachment variation. At first glance, these foals appear to have a valgus fetlock.

4. Spiral - Spiral deformity involves the metacarpal in the majority of cases but can also involve the metatarsus. At first glance the spiral deformity resembles toed-in conformation. The author refers to this deformity as heeled-out, as the pure spiral does not have a varus fetlock.

5. Flexor Anomalies - Flexor contraction and weak flexors are often found at birth.

How to Assess Foot Flight and Leg Alignment

Start by watching the foal walk straight away from you, preferably on a smooth surface. Walking the mare along a wall or fence offers a reasonable means of assessing the foal as he travels beside the mare. Focus on foot flight and the landing phase. Watch the hind feet land several times before focusing on the front feet as the foal moves away from you. Foot placement and full load stance appears to occur faster than the eye can detect, but with practice the landing phase can be observed in a slow motion mode. Closely observing the air space under the foot as it lands and loads acts to slow the action and brings out subtle details that might otherwise be overlooked.

Next, observe the foot flight and landing pattern of the front feet as the foal comes back toward you. Watch the lateral wall of each front foot land, then observe the medial wall. Note any differences between the two feet. Turn the foal and watch him go away from you once again. This time observe the hind limbs, one at a time, from the hip to the ground as the limb flexes and extends to full length. Placing an imaginary dot at each major joint creates a reliable means of evaluating the angulation. Once both hind limbs are observed focus on the front limbs, paying particular attention to the carpass and the heel of each front foot. The heeled-out foal (spiral deformity) and bowed knee (varus carpass) becomes readily detectable by the trained eye as the foal moves away from you.

As the foal walks back to you observe only the front limbs, one at a time, from the shoulder to the foot. Once again, place imaginary dots at each joint. Connect the imaginary lines between the dots as the limb flexes and extends, and as the foot lands. Foals that aren't broken to lead well are more difficult to observe, but with practice the eye can be trained to follow the dot system even at a trot.

Once the foal has been evaluated while moving, observe him standing as squarely as possible and in a relaxed position. Assign imaginary dots in the following 7 places:

• 1st dot: Most proximal point on the forearm. A small swirl of hair is normally located at the top and center line of the radius.

• 2nd dot: Center of the distal radius at the level of the physeal plate.

• 3rd dot: Center of the most distal aspect of the carpass.

• 4th dot: Center of the proximal cannon. Note this dot will be superimposed over dot 3 unless axial deformity (offset knees) is present.

• 5th dot: Center of fetlock.

• 6th dot: Center of coronary band.

• 7th dot: Center of toe.

As the dots are observed, visualize an imaginary line between them and note any deviations of those lines. Next, imagine an imaginary laser or arrow centered on each dot, passing through it on the sagittal plane of the limb at that point. Observing these imaginary lines is a reliable, consistent method for identifying planes of deviation that can and often do occur between major joints. Using the dot system helps train the eye to look for minute details that may otherwise be missed in addition to greatly enhancing communication between those observing the foal.

Each type of deformity can be graded on a scale of 5: 1. Noticeable to the trained eye. 2. Noticeable to the experienced horseman. 3. Noticeable to the inexperienced horseman. 4. Noticeable to anyone. 5. Off the scale - catastrophic class deformity.

Any given individual may have several types of deformities in any one limb. Developing this system and using it in a disciplined, methodical fashion offers a reliable means of assessing foot flight and leg alignment. Identifying the real problem is a vital step for an efficient treatment protocol.

Valgus Deformities Treatment Options