Originally published on TheHorse.com
Your equine athlete's performance hasn't been blue ribbon-worthy as of late. Or maybe your broodmare's gaits are looking a little off kilter. Could long toes on the hind feet be to blame? According to the results of a recent study, the answer in some cases is yes and sometimes the solution can be very simple.
"The hind limb stance in (horses with long toes) is one in which the load-bearing surface of the hoof appears to be too far forward in relation to the coronary band and to the fetlock and cannon bone," said Richard A. Mansmann, VMD, PhD, hon. Dipl. ACVIM, professor emeritus at North Carolina State University's College of Veterinary Medicine, where this study was completed, and owner of the Equine Podiatry and Rehabilitation Practice in Chapel Hill. "These horses tend to 'stand under themselves' with their hind feet, meaning that at rest the foot is placed further forward than normal in relation to the vertical axis of the limb and the main mass of the hind quarter, giving the horse a sickle-hocked appearance."
Armed with that information, the research team set out to determine if long toes could be a cause of gluteal (the muscles that run along the back of a horse's hindquarters on either side of the tail) pain in horses, and if corrective trimming and/or shoeing could correct the problem and eliminate the pain.
A radiograph illustrating breakover distance (the horizontal distance between the red arrow and red line).
Mansmann noted that the term "long toe" is too subjective to use in a research study because of varying opinions on exactly what constitutes long. Thus, the team determined the hooves' breakover distance as an objective measure in the study. They did this by measuring the horizontal distance between the tip of the horse's coffin bone and the dorsal-most point at which the hoof wall or shoe came in contact with the ground, as seen on lateral radiographs. He added that for the average-sized horse, the ideal breakover distance is likely between 0 and 20 mm.
The researchers evaluated 77 client-owned horses that were either examined by a team member in the field or were presented to the private practice from April 2006 to December 2007. The horses were either low- to medium- level performance horses or nonpregnant broodmares of various breeds, ranging in age from 4 to 24 years old. All of the horses had at least one set of lateral radiographs taken of their hind feet and on the same day Mansmann palpated their gluteal muscles.
The team split the horses into two groups: 67 shod horses and 10 barefoot horses.
In the group of shod horses, 50 out of 67 tested positive for pain (i.e., displayed an exaggerated response to palpation that consisted of one or more of the following: buckling of the hind limbs, pinning the ears back, threatening to kick the examiner, or kicking at the examiner) and 17 horses tested negative (did not react to palpation).
The average breakover distance for horses that displayed a positive response to palpation was 24.2 mm, while the average breakover distance for negative horses was 18.8 mm. The researchers noted that "although small, the difference in mean breakover distance between positive and negative horses was statistically significant."
In the group of barefoot nonpregnant broodmares (all housed in the same environment and not being ridden) all 10 displayed positive reactions to palpation. The average breakover distance for this group of horses was 25.6 mm.
To evaluate whether corrective trimming or shoeing could resolve the gluteal pain, the team reduced the breakover distance in all the painful horses' hind limbs and reevaluated the animals:
Only 24 shod horses (of the 50 that had been found painful) were available for a follow-up evaluation four to six weeks after corrective trimming or shoeing; however, all of those horses showed reduced gluteal pain. Twenty of the horses were negative for a reaction to palpation and the remaining four were only mildly positive (the researchers noted that all four of those were negative to palpation after another four to six weeks and a second corrective trim). The new average breakover distance for these horses was 10.9 mm.
All of the barefoot broodmares received follow-up evaluations one week after corrective trimming. Eight of the 10 were negative for reaction to palpation and two were mildly positive. The average breakover distance for these horses after corrective trimming also was 10.9 mm.
"Excessive toe length in the hind feet might be accompanied by pain in the gluteal region," Mansmann wrote in the study. "Shortening the toe can alleviate this pain within days or weeks."
The team added that "in cases where the toe length or gluteal pain was adversely affecting the horse's comfort or function, one could also expect an improvement in the horse's gait and performance after remedial trimming or shoeing."
So how can you tell if your horse's feet are causing him gluteal pain or if they might require evaluation?
Mansmann explained that most horses in need of a hind end evaluation will display behavioral problems including not performing as expected, not being willing to move off the leg, or stopping at jumps. He also noted that these horses might display signs of a sore back. Additionally, "any horse where their hind foot coronet is slanted such that an extended line (following the coronary band line) hits them behind the elbows should be evaluated," he said.
He added that most farriers, with the aid of the veterinarian and hind foot radiographs, can evaluate and adjust the breakover for a particular horse if needed.
The study, "Long Toes in the Hind Feet in the Gluteal Region: An Observational Study of 77 Horses," was published in the December 2010 Journal of Equine Veterinary Science. The abstract is available online.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.