By Breanne Hill—Photo by John Brasseaux

_249Navicular is a bone, not a lameness disorder.

This is the message veterinarians are trying to communicate to owners who have horses that are suffering from pain and lameness in the back of the foot and leg.

The tiny navicular bone is the lowest bone located in the back of a horse’s foot. It touches—is almost wedged between—the short pastern bone, which is above it, and the coffin bone, which is in front of it.

Due to this small bone’s location and because it is the recipient of a lot of weight and force, the navicular bone has long been pinpointed as the source of pain when a horse comes up lame in the back of the foot and leg. However, with the advent of new medical technology, veterinarians have changed the way they evaluate “navicular” and the role its namesake bone plays in lameness. In fact, doctors no longer officially refer to the issue as navicular, but rather as palmar (in the back) foot pain.

Dr. Britt Conklin, DVM, CF, is a veterinarian, certified farrier and co-owner of Reata Equine Hospital and Podiatry Center in Weatherford, Texas. He explains that the change in name from navicular to palmar foot pain was due in no small part to what veterinarians have seen thanks to sources such as MRI imaging, which allows doctors to peer deep into the internal structures of the body.

“Navicular was a name we used as a sort of catchall for pain in the back of the foot,” Conklin says. “What we were saying, essentially, is that everything had to do with that bone. Now, through imaging, we see that it’s not just about the bone. It could be a tendon. It could be a ligament. It could be any number of soft tissue structures associated with the back of the foot.”

In other words, there can be many factors that contribute to pain in a horse’s foot, and those factors can originate from a bevy of controllable and uncontrollable sources.

What Causes Palmar Foot Pain?
According to Conklin, these are some of the primary causes of the disorder:

– Genetics
diagram“From what we know, it can be genetic,” Conklin says. “In other words, a horse can have a predisposition for it. This doesn’t mean they’re born with the foot pain. It means that if a parent had some weakness in the navicular bone, it can get passed on. Then, when the horse gets old enough to have a job, you can see some problems develop.”

– Conformation
“If your horse is badly conformed, say, with a long toe, low heal and very thin digital cushion [a structure in the back of the hoof that protects the region around the navicular bone], then he can’t absorb the amount of concussion that a horse with an upright hoof structure, a lot of frog and a lot of digital cushion can,” Conklin says. “So after a while, if you’re running on a lot of hard ground, and you get exaggerated concussion in that area, you could end up with a damaged bone.”

– Bad Shoeing  
“A horse that has been shod wrong, especially if his conformation isn’t ideal, is going to have a lot of stress put on his tendons and ligaments,” Conklin says. “The foot isn’t landing symmetrically. They aren’t landing flat. Imagine landing wrong on your foot and slapping the same area over and over again. Over time, that can cause strain and even tear tendons and ligaments.”

– Traumatic Events
“There’s no way an owner can control this, but horses can be running out in the pasture and step in a hole and tear part of the deep flexor tendon,” Conklin says. “These traumatic events happen all the time with horses.”

– Wear and Tear
“Barrel horses, and rodeo horses in general, are susceptible to palmar foot pain, more so than cutting horses and reining horses and race horses,” Conklin says. “They have jobs that require short bursts of energy and hard stops and turns. That all contributes to stress on the legs and feet.”

– Poor Management
“As an owner, you have to keep up with what you control,” Conklin says. “You can’t control wear and tear except by not running your horse in arenas that are rock hard. You can control early detection. Don’t let your horse keep running if something is wrong. Don’t try to bute your way through it. Get a diagnosis. You can also control foot management. Get yourself a good competent farrier who really pays attention to your horse’s needs.”

While it’s tempting to diagnose your horse with palmar foot pain at home, you should take animals that appear to be in pain for more than three days to a veterinarian for an official diagnosis and treatment.

You can, however, watch out for these warning signs that your barrel horse might be developing a problem:
—Slower performance times, accompanied by a hint of lameness toward the back of the foot
—Refusal to turn barrels or running past barrels, accompanied by a hint of lameness toward the back of the foot
—Suddenly running stronger in one direction than in the other
—A distinctive head bob when running, as if the horse is struggling to get along
—Walking or running on the toe of the hoof instead of the whole hoof

REMEMBER: Palmar foot pain has only been reported on a limited basis in the back legs. It is primarily found in the front legs.


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