Choosing your next Equine Athlete on Conformation

Conformation of the Juvenile Equine Athlete

The conformation of horse’s forelimbs have a lot of attention paid to them because of a perception of a predisposition to injuries, Liz Santschi DVM, Dipl. ACVS, clinical associate professor at the University of Wisconsin-Madison, says.

She was speaking at the Western Veterinary Conference held in Las Vegas, Nevada in 2005.

However, many deformities are very common such as:

·         Angular limb deformities (limbs that are crooked when viewed from the front)

·         Rotational deformities (such as toeing in or out)

·         Offset deformities (bench knees)

Yearlings with bench knees are now often subjected to surgery to make them knock-kneed based on observations that horses with both bench and knock knees are less prone to injuries than those with just offset knees, Dr Santschi said.

"I imagine that it is confusing to clients as for years we've been telling them that carpal valgus (knock-kneed) needed correction, but now we're telling them it's desirable.

In Dr Santschi’s study, racing-bred Thoroughbred foal forelimb conformation was evaluated shortly after birth and repeatedly as the foals matured. She found that nearly all foals were carpus valgus (knock-kneed) at birth, many toed out, and very few had offset knees. But the incidence of conformational deviations changed quite a bit as the foals grew up. As long yearlings, nearly two-thirds had offset knees and the incidence of knock knees had dropped by a large margin. Less than 10% of foals were considered to be completely straight in the forelimbs at any age, and more than half had more than one conformational deviation.

Another finding was that heavier birth weight of the foal was associated with knock knees throughout their lives.

Dr Santschi found that a combination of nature and nurture contributed to the condition of a horse’s forelimbs.

"Limb conformation is determined by a genetic template that is impacted by developmental processes and environmental influences tempered through biological constraints."

However, the condition of the parent’s legs played a large role in their offspring’s condition.

Conformation Correction 

Dr Santschi argued that hoof augmentation on foals reduces toeing in and correcting severe knock knees was useful. It was also important to remember that avoiding bone crushing from unbalanced loading of bones not yet fully hardened was at least as important as surgical therapy.

"Periosteal (limb) elevation may accelerate self-correction, but is mostly unnecessary with regards to ultimate conformation. However, it may have value to prevent crushing carpal bones (by correcting poor conformation more quickly and thus reducing the amount of time carpal bones undergo unbalanced stress)."

Misshaped bones can result from abnormal forces on normal limbs (compensatory overload) or normal forces on abnormal limbs (hypoplasia). “Limbs become permanently and severely deformed when abnormal forces are placed on abnormal limbs, resulting in progression of deformity,” she said.

Dr Santschi said hoof augmentation was a good solution to bones dealing with compressive strain, because it changed the loading on the bone.

"What we start with are foals that at birth have various degrees of overall musculoskeletal maturity, and occasionally have focal immaturity," she said. "When these tissues (bones and soft tissues) are less mature, they are more susceptible to load. If we can keep them from pounding (asymmetrically) on those soft little bones, they'll be OK.

"Most limb deviations in foals are a normal developmental process, or the result of musculoskeletal immaturity," she said. "Some require more specific management, but will improve after careful evaluation and management changes (such as restriction of exercise). And a small number of foals will require more specific therapy such as hoof trimming and augmentation, external coaptation (casts and braces), and/or surgery."

Source: Christy West, www.TheHorse.com

Add your Comment

Name*

Email

Message*

Enter the letters above

Get a different image