Limb Deformities - Introduction

Hans Castelijns is a veterinarian and farrier who is exceptional in his knowledge and experience with foals.
See end of chapter for consulting information. Please consult his web site for further information about foal hoof and limb management: www.mascalcia.net/articoli/a2000_28a.htm

I. General

1. "Correct" leg conformation is important to obtain a good price at the sales, sustain a successful training regimen in the young adult, to attain a high score at shows, and perhaps most important, to prevent lameness during a long career of the sport or racehorse.
2. Leg conformation, and associated defects, is heavily influenced before birth by genetics of the parents.
3. The mare’s influence is of course both genetic, although it usually takes several offspring to notice, and environmental, therefore management of the mare is an important factor. Obese mares (during pregnancy), tend to have a higher incidence of foals with angular deviations at birth. This higher incidence, specifically at the level of the carpal and tarsal joints, with a lot of "windswept" foals (one hock varus the opposite valgus), could be due to reduced uterine space caused by excessive abdominal fat.

II. Evaluation of Limb Conformation

1. Evaluation of the foal for its conformation at, or soon after, birth is useful in all foals and essential in high-risk cases: twins, prematures, dystocias, and previous history of limb problems from foals of similar breeding.
2. Evaluation should take into account:

1. That a foal is not an adult:

1. A base wide, outwardly rotated stance of the front legs is perfectly normal in lighter breeds, as it increases stability of these long legged, narrow breasted babies, and tends to "correct" itself with time.
2. This stance should not be confused with a valgus fetlock when seen from the front. In fact the best view for catching angular, and especially rotational deviations, of the front limbs is the skyline view, looking down from the shoulder to the toe, evaluating how the radius aligns with the cannon bone and the cannon bone with the pastern and the hoof.

2. The age of the foal.

1. Growth plate closure times can be defined functionally, radiologically and histologically (Table I). For correction purposes, the first are essential.
2. Distal growth plates (proximal of PII, proximal of PI, distal of MC/MTIII) close functionally within the first 3 months, followed by the distal GP of the tibia and finally the distal GP of the radius
3. Food intake changes naturally with age; developmental orthopaedic disease (D.O.D.) is due mostly to excess, not only of protein but also of energy (carbohydrates). Limiting energy intake takes a different approach in the new born as opposed to a 3 month old, which is grazing on lush spring pastures and/or might have access to crib feeding.

3. Body condition score and weight.

1. An upright pastern is normal in the lightweight newborn; the fetlock should naturally extend further (drop) with increase in body weight.
2. The breed. For example: Quarter horses and Andalusians are already "stocky" at birth and have higher incidence of varus deviations than, for instance, thoroughbred foals. A slight inward rotation of the lower hind leg is as lot more serious in a Standardbred trotter than in other breeds as it will probably lead to a cross gaited movement and interference at lower to medium speeds in future training.

3. Evaluation should be performed viewing the foal/limb:

1. From the side to spot abnormalities in the sagittal plane (flexural deformities).
2. From the front or the back to spot angular deviations in the frontal plane.
3. From above to look for axial rotations in the horizontal plane.
4. Bear in mind that the same foal, indeed the same limb, often presents a combination of flexural, angular and rotational deformities.