Angular Limb Deformities

Dean A. Hendrickson, DVM, MS

Diplomate, ACVS

Definition - A valgus angular limb deformity (ALD) is one

where there is a deviation of the lower leg in a lateral

direction from the normal axis, whereas a varus ALD is a

deviation in a medial direction of the lower leg from the

normal axis. In most cases, the terminology is derived by

combining the name of the involved joint or the joint

immediately distal to (below) the affected growth plate

(physis) and the direction of the deviation. (Figure 1. Carpal

Varus, Figure 2. Carpal Valgus) The most common type of

ALD is a carpal valgus.

Clinical and Physical Examination - The age of the foal at the onset of

clinical signs is very important in determining the possible causes of

the ALD. The most common reason for an ALD is abnormal growth at

the growth plate, and often is seen at birth. However, it is possible for

an ALD to occur as the foal matures when it bears too much weight on

the leg. Another cause of ALD occurs when the cubiodal bones of the

carpus (knee) and hock are not formed properly in-utero, and they

collapse as the foal bears weight. This is most commonly seen in

premature foals. The use of radiology is necessary to determine if the

cuboidal bones are normal. (Figure 3. Malformed cuboidal bones,

Figure 4. Abnormal growth plate). Consequently, it is very important to get your veterinarian

involved very early to make sure what is going on in the joint. Cuboidal bone problems can be

career ending if not treated immediately.

Treatment – There are many ways to treat ALD’s, dependent on the degree

of abnormality and the age of the foal. Foals with cubiodal bone problems

generally need to be placed into a “tube” cast to protect the abnormally

formed bones from collapsing. (Figure 5) Foals with growth plate

abnormalities can be treated with anything from limited exercise, to foot

trimming, to glue on shoes, and finally to surgery to help to straighten the

leg. It is important to realize that the growth plates close at different times,

and that after the growth plate closes, it is much more difficult to change the

deformity. It is also important to realize that severe ALD’s need to be aggressively treated with

surgery. (Figure 6) This table will give some rough guidelines as to when conservative versus

surgical therapy should be instituted. However, it is critical that your veterinarian be consulted as

soon as possible to give your foal the best opportunity to have a straight leg as it matures.

Region Conservative Treatment Transphyseal Bridging Stops Growing

Fetlocks <2-3 weeks 4 weeks 9 months

Carpus (knee)/Hock <2-3 months 4 months 21 months

Figure 1 Figure 2

Figure 3 Figure 4

Figure 5

Figure 6