When a Foal’s Legs Don’t Look Quite Right: The Foal Deformity Lowdown
You selected your stallion, prepared your mare, confirmed the pregnancy, watched her grow this baby you dreamed of and then - the baby is born with crooked legs. What now?
One study found that 66% of foals are born with crooked legs.*
Two out of every three babies.
So if you are experiencing this scare with your foal, you’re actually in the majority.
The great news is that less than 10% of these foals require intervention, and the other 90% of cases correct on their own.
What Is a Foal Limb Deformity?
A limb deformity is just what it sounds like. It is when the foal’s legs that should be straight instead appear crooked or appear to bend in directions that they shouldn’t be bending.
These limb deformities are often present at birth, but can also develop after birth. The deformities often occur because of ligament laxity or muscle weakness, but can have other causes too.
Common Types of Limb Deformities
Angular Limb Deformities (ALD):
The most common type of limb deformity is an angular limb deformity (ALD). Angular limb deformities occur in the frontal plane meaning when you look at the horse from the front, the legs are bending toward the midline or away from midline.
A valgus deformity is when the legs are bending toward the midline
Valgus deformations can occur at the:
Carpus - this gives a knock-kneed appearance
Fetlock - this gives a toes pointing out appearance as the fetlocks fall in
Hock - this gives a cow-hocked appearance
A varus deformity is when the legs are bending outward away from the midline.
Varus deformations can occur at the:
Carpus - this gives a bow-legged appearance
Fetlock - this gives a toe in appearance as the fetlocks fall out
Hock - this gives a bow-legged appearance in the hind legs
Angular limb deformities with one leg valgus and one leg varus will have both legs bending the same direction and will give a windswept appearance - both legs deformed to the right or both legs deformed to the left.
Flexural Limb Deformities (FLD)
Flexural limb deformities are when the leg is bending too far forward or too far backward - these are deformities in flexion or extension.
Contracted tendons are when the flexor tendons are too tight. They can create an appearance of over at the knee, or over at the fetlock. Foals will often look like they are walking on their very tip-toes because they are not able to place their heel on the ground due to the tight flexor tendons.
Lax tendons are when the flexor tendons are too loose. The leg will present in hyperextension. This will often present as dropped fetlocks, but can also appear that the carpus is hyper extended as well.
Rotational Deformities
Rotational deformities are created by a twisting of the limb and appear as a toed-in or toed-out stance.
A toed-in stance is often called “pigeon-toed” and a toed-out stance is often called “splay footed”.
These foals can often be corrected by trimming the feet to balance them. If they are not corrected they can create uneven wear patterns on the feet.
Combination or Complex Deformities
As the body tries to find a vertical balance in the limb, it is common for a combination of deformities to occur such as a varus at the fetlock compensating for a valgus in the carpus. Although these cases can appear more complicated, the same rate of self correction is still around 90%.
“The most frequent congenital abnormalities were carpal valgus (42.1% of the foals), fetlock valgus (31.2%), over-at-the-knee (30.8%) and dropped fetlocks (13.0%)” *
Causes and Risk Factors
One of the most well studied risk factors for limb deformities is premature birth. Horses have a very large window of what is considered a normal gestation period ranging from 320 to 380 days.
According to this study, the odds of limb deformity decreased by 4% per day in gestation length between 314 and 381 days.
Other causes include twin pregnancies, nutrition imbalances (especially mineral imbalances), trauma during pregnancy, and colic.
How Vets Diagnose Foal Limb Deformities
When you recognize your foal has an angular limb deformity, it is important to schedule an appointment with your vet to establish a treatment plan.
A vet will look at the legs, do a manual assessment to check the stiffness or laxity in the limbs, and may suggest radiographs.
A radiograph will be the most precise way to determine the degree of severity and monitor progress.
Treatment Options
Conservative (Non-Surgical) Treatments
If your vet determines that your foal needs intervention, they may decide to start with a more conservative approach first such as:
Taping
Splinting and casting
Trimming
Stall rest
Medication
Taping is the least invasive option. It will act as support to the tendons and ligaments to promote correct alignment.
Splinting and casting will limit the range of motion of the leg by placing the leg in a rigid device to hold the correct shape of the leg while the foal grows to promote correct alignment of the joints.
Trimming the feet can change how the foal’s feet strike the ground and how the force is directed on the joints of the limb. In more severe cases, a hoof care provider can place a special shoe on the foot to have even more control over the direction of force on the limb.
Stall rest will limit the foal's movement and allow the joints to be balanced without the baby running and making sharp lateral movements during play.
Medication - a broad spectrum antibiotic by the name Oxytetracycline can be given intravenously in a high dose to relax tendons in a flexural deformity.
Surgical Treatments
If it is determined that surgical intervention is necessary, there are options for what approach is best for your case.
For angular limb deformities, a vet may choose:
periosteal elevation for mild to moderate deformations or
transphyseal bridging for more severe deformities
Periosteal elevation is when the tissue that covers the bone (periosteum) is cut on the slower growing side to accelerate growth on that side. This is done relatively early while the growth plates are active.
Transphyseal bridging is when a device such as a screw or wire is placed on the faster growing side to slow the growth. This can be done in more mature foals, but the device will have to be removed.
For flexural limb deformities, a desmotomy can be done. It is a surgical cut made most commonly to the inferior check ligament to allow room for the flexor tendons to lengthen so that the foot can sit flat. In extreme cases
Surgical repair is more emergent in the feltlock than the carpus. Repairs at the growth plate are usually done around one month, and must be done by two months to be most effective.
Aftercare and Monitoring
No matter what intervention you and your team may choose, each will require their own monitoring.
Tape: keep an eye on the tape to make sure the foal is not chewing on the tape. If the foal wants to chew on the tape, very gently wrap the leg in vet wrap.
Splinting and casting: keep an eye on the skin to make sure there are no pressure areas or sores from the splint or cast. In some cases, the splint or cast may need to be re-shaped as the shape of the leg improves.
Trimming: monitor how the foal responds to the trims by watching how the walk and stand
Medication - monitor your foal’s overall health such as appetite, energy, and mood
Surgical intervention: follow all post-op protocol from your vet to ensure correct healing. This may include bandage changes, stall rest, specific exercises, and the overall health of the foal such as appetite and demeanor.
Prognosis: What to Expect
Overall, your foal has a very high chance of this being no big deal. Around 90% of foals self-correct, and the other 10% usually respond well to intervention.
In the most extreme cases a foal will be so extreme that it will have an incredibly poor quality of life and it will need to be humanely euthanized.
This is the kindest thing we can do for the small percentage of these babies.
When to Call Your Veterinarian
You should have a working relationship with your vet regarding this mare’s pregnancy in general, so don’t hesitate to reach out to your vet as soon as you notice the deformed limbs. Send them pictures and let them decide what the next course of action is.
Prevention Tips
Most cases of foal limb deformities are out of our control, but ensuring a proper diet for the mare during pregnancy and proper mineral balance is a great way to prepare for the best.
The most solid research on limb deformities shows that the longer a mare gestates, the higher rate of straight and healthy limbs - so don’t rush your mare’s pregnancy, get comfortable waiting on that baby.
Where to Get Help and What to Know
The most important take away is to know that your baby is most likely going to be just fine. Reach out to your vet and establish a plan of care for your specific case.
If you’re looking for a way to support your baby as they straighten out, tape is a very non-invasive and effective way to support them.
A horse owner can manage this on their own from home, without making trips to the vet regularly with my Foal Deformity Corrections class.
This class includes taping directions for 10 different applications so that you have the knowledge you need to support babies with straight legs.
Not ready to enroll but want to stay up-to-date on all things equine education?
Join the Sozo Equine® Email List!
Next on your reading list:
*Longitudinal development of equine forelimb conformation from birth to weaning in three different horse breeds,” C. Robert, J.-P. Valette, and J.-M. Denoix. The Veterinary Journal