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From The Ivory Tower | Angular and Flexural Limb Deformity

Angular and Flexural Limb Deformity in the Foal

Although angular and flexural limb deformities are common abnormalities in newborn and young growing foals, the important thing to note is that these are typically easily corrected given that the abnormality is properly recognized and addressed in an appropriate time manner.  Foals can either be born with or acquire over time various angular and flexural limb deformities.  It has been suggested that congenital limb deformities (ones that foals are born with) could possibly be caused by genetic predisposition, poor nutrition of the mare during gestation, and bad positioning within the uterus during gestation.  Numerous things including rapid growth, genetic predisposition, trauma, nutritional imbalances, and over-feeding of foals can cause acquired limb deformities (one that foals develop after birth).


There is a distinction to be made between an angular limb deformity and a flexural limb deformity, as they are not the same.  An angular limb deformity is noted as one views the foal's legs from either the front or the back, while a flexural limb deformity is noted as one views the foals legs from the side.



Angular Limb Deformity (ALD)

Angular limb deformity is a limb deviation either laterally (hoof is farther from midline than normal) or medially (hoof is closer to midline than normal).  Angular limb deformities typically affect the carpal region (often inappropriately called the 'knees') of the forelimbs but the tarsal region (or hock) of the hindlimbs can also be affected.  It is also not uncommon to have an angular limb deformity of the fetlock region, especially when there is a deformity of the carpal/tarsal regions already.  Typically the deformity of the fetlock is in the opposite direction of the deformity higher on the limb.


Certain terminology is used to describe the angular limb deformity.  When the deformity results in a lateral (away from the middle of the body) deviation, it is described as 'valgus.'  Using the carpal joint of the forelimb as an example, a foal with an angular limb deformity resulting in the hoof being further away from midline (more lateral) would be one described as having carpal valgus.  For many lay horse-people, this condition is often referred to as 'knock kneed' (termed inappropriately as the carpal joint of the equine limb is in fact analogous to the human wrist and not the human knee).


When the deformity results in a medial (toward the middle of the body) deviation, it is described as 'varus.'  Using the carpal joint of the forelimb again as an example, a foal with an carpal angular limb deformity resulting in the hoof being closer to midline (more medial and more underneath the body) would be described as having carpal varus.  This condition is often referred to 'bow-legged' by the typical horse-person.



Flexural Limb Deformity (FLD)

Flexural deformity is a limb deviation where excessive flexion or extension is seen in one or more joints when viewing the foal from the side.  Flexural deformities present at birth are thought to be the result of fetal positioning with the uterus during gestation.  Typically these will correct themselves within the first 3-5 days of life provided that the foal has repeated opportunities for brief exercise in a small paddock turn-out.

Flexural limb deformities are named by the joint and direction in which they occur.  Excessive joint flexion is termed ‘contracture’ while excessive joint extension is termed ‘hyperextension.’  Some flexural deformities have specific names that are commonly used by horse people.  A ‘club foot’ is the result of contracture of the coffin joint that wasn’t properly addressed in a timely manner.  Contracture of the fetlock joint is commonly termed as a ‘knuckling fetlock.’



Treatment Options

Correcting either angular or flexural limb deformities include a variety of treatment options.  The degree and severity of the deformity, as well as the age of the foal, will help determine the best course of action.  It is very important that the foal be monitored closely during the first week of life so that early intervention can be planned should a limb deformity arise.  Beyond that, owners should always be mindful that foals grow very rapidly, sometimes too rapidly, and this is where many issue arise.  If anyone is concerned about the growth and well-being of their foal, they should plan to have a veterinarian make an assessment and plan treatment if necessary to help limit the degree of the deformity and ultimately lead to correction.


There are a number of treatment options in dealing with limb deformities.  Sometimes simple controlled exercise is all that is needed to help with correction.  Other times, radiographs may need to be taken to determine the best course of action.  An important aspect of managing these issues is having a mindful and watchful owner that can recognize developing issues and will initiate the steps for corrective treatment.

Another important aspect in dealing with limb deformities is the veterinarian-farrier relationship.  Some angular limb deformities can be resolved with farriery.  It’s always a good idea to get everyone involved in the health of a young growing foal to ensure all are on the same page.  Foals only get one opportunity to grow correctly.  Fortunately, we have treatments at our disposal for almost any type of angular or flexural limb deformity.  The most important aspect of managing these cases (or any case for that matter) is early recognition and prompt initiation of treatment.


If your newborn foal emerges, stands, and the legs resemble anything seen on this page or if your young growing foal's legs look crooked, don't wait and assume it will "grow out of it."  Early intervention gives foals the best chance at having normal looking and normal functioning limbs.


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