Trimming's Effect on Horse Hoof Morphology

Farriers use a wide range of trimming techniques they use to improve the health and structure of each equine foot and hoof capsule on which they work.

During the 2017 International Hoof-Care Summit, held Jan. 24-27, in Cincinnati, Ohio, Brian Hampson, PhD, co-founder of the Australian Brumby Research Unit at the University of Queensland, Australis, presented the results of a study that looked at the effects of four trimming models on hoof morphology (form and structure).

Study Overview

In his study, Hampson evaluated 22 horses from the United States and Germany on which one of four trim types were performed over a 12-month period. His goal was to document morphologic changes associated with various barefoot hoof care models and to determine if hoof capsule changes occurred in relation to trimming philosophies. He also aimed to find out if the palmar soft-tissue volume within the foot changed over 12 months. He didn’t seek to determine if one trim method was better than another.

Hampson’s research team analyzed data provided by four farriery trimming schools which agreed to have students trim horses every four to six weeks according to their taught trim method and share their results. Photos and radiographs were taken before and after each trim. The farriers/trimmers selected study horses with healthy, disease-free hooves they thought they could change. Each farrier started with hooves that had not been trimmed in the previous six weeks.

The Trimming Methods

Hampson described the four schools’ trimming methods to the audience:

  • “Barefoot Hoof Orthopaedics (BHO)” from Dr. Konstanze Rasch of Germany: This technique doesn’t allow significant adjustments to the hoof wall from trimming underneath, because the belief is that it will stress the joints above. Instead, the farrier will thin the wall from the outside and let the natural movement of the horse trim the hoof down.
  • “Natural Hoof Care” from Dr. Tina Gottwald of Germany: This method uses a trim similar to those used for wild horses (the “mustang roll”) by rolling the hoof wall all the way around and taking the hoof back to the white material/wet line.
  • “Pacific Hoof Care Practitioners (PHCP)” from Sossity Gargiulo of the United States: This method keeps the outside hoof tubules from interacting with the ground by using a trim similar to wild horse trims by rolling the hoof wall almost all the way back to the heel.
  • “HoofPrint Method” from Cheryl Henderson of the United States: This trim creates a rocker toe and a thinner hoof wall.

Key Study Findings

The study results confirmed that trimming can change hoof capsule morphology. Some changes were positive, such as increased palmar ground support length and reduced toe length. Hampson’s team viewed resulting reduced sole depth and excessive shortening of the toe as negative effects of trimming.

Changes only varied incrementally based on the applied trimming method. Additionally, Hampson and colleagues found that hoof capsule changes might not align with or be as significant as proposed by each trim type’s advocates. Finally, they found that changes in palmar soft-tissue volume did not change relative to hoof capsule changes over the year-long study.

In his summary, Hampson discussed the importance of the hoof wall, especially at the toe and in the buttresses (in the back near the heels). “It’s thick here (in the back) because the heels slam on the ground in the heel strike in weight-bearing,” he said. “In toe off, there’s large movement forces in the dorsal foot, so you need a lot of meat to absorb that shock.”

Hampson said he’s not a fan of the excessive mustang roll, which involves trimming the hoof wall into a rolled look all the way around the hoof so that the horse bears more weight on the inner hoof wall and the sole. He said it’s not natural like many mustang roll fans promote. In his work with wild horses, he said he’s never seen a wild horse’s foot look like the mustang roll unless the horse was on the verge of death, traveling excessive mileage to survive drought conditions, or climbing rocky mountainous country to access feed.

“I don’t see the point in cutting that (the hoof wall) off, and I really haven’t had anyone give me a good explanation for why that’s done,” he said. “I’m not convinced that’s a natural horse’s foot.”

Additional Observations

The researchers also observed that:

  • None of the horses had perfectly symmetrical feet, and hoof morphology varied between horses;
  • No change occurred in distal phalanx (coffin bone) length, lamellar zone thickness (the distance between the laminae and the outside of the hoof wall), or sinker distance (the depth the bony skeleton had sunk over time into the outer hoof). There was no change overall in heel bulb length, palmar angle, dorsal hoof wall angle, and frog width in any group;
  • All the groups except BHO reduced the distance from the tip of the distal phalanx to the lamellar zone;
  • The horses had an overall 20% reduction in sole depth (2.9 millimeters) with no difference between the four methods;
  • All but the BHO horses had an overall 26% reduction in toe length (range of 8% from one group to 40% from another);
  • Hoof length didn’t change, but PHCP achieved a 10-millimeter reduction while BHO achieved a 7-millimeter increase;
  • The horses’ dorsal foot length decreased by 25% overall, while the BHO group experienced no reduction;
  • Overall palmar foot length increased by 8% (7 millimeters, with a range of 3-10 millimeters);
  • Heel angle increased by 2% overall (range of 5.8-degree reduction to 6.2-degree increase, with the increase not being significant);
  • The horses’ heel width reduced by 6.3 millimeters overall (ranging from an 18-millimeter reduction to a 2-millimeter increase with the PHCP trim).
  • An overall 2.5-millimeter reduction occurred in foot width (9.8-millimeter reduction to a 5.8-millimeter increase)
  • Horses that experienced the most aggressive toe trimming had the greatest reduction in foot length, the smallest increase in palmar foot length, a reduction in foot width, a 6-degree reduction in heel angle, and no change in heel width.

Take-Home Message

Hampson emphasized that good hoof trimming isn’t purely a science.

“Instead, it should be based on a combination of measurement ‘guides’ and a good knowledge of the biological and biomechanical consequences of hoof length and angle changes,” he said. “This is where art and science combine to produce the best results for the horse. Hoof care recipes work sometimes for some horses but will be detrimental for others.”

The results from this study will allow veterinarians, farriers, and horse owners to have more information with which to make educated decisions about hoof care, he said.