Last Updated on February 25, 2022 by Allison Price
Quarter cracks in horses’ hooves can ruin their riding plans. They can take many months to fix, even with the expertise of a veterinarian and hoof care professional. In the worst cases, they can cause permanent lameness.
These cracks are named so because they occur in the heel quad (back half, one quarter of each foot on either side of the foetus) of the horse’s hoof wall. They are usually located vertically and originate at the hairline.
These problems can arise from hoof imbalances or other issues and require a multimodal approach to solve them, according to Stuart Muir NZCEF CJF, Dipl. WCF, APF is the resident farrier at Rood & Riddle Equitation Hospital in Lexington, Kentucky. He works closely with Scott Morrison, DVM and other veterinarians. Muir spoke out about quarter cracks and the problems they pose during the 2020 American Association of Equine practitioners’ Annual Convention.
What causes quarter cracks?
The severity of quarter cracks varies. They can cause mild lameness or can go beyond the hoof wall and cause bleeding. These cases are more severe and can result in a 3–5 point lameness score on the AAEP’s 5-point scale. 5 is non-weight bearing.
Quarter cracks can also expose the hoof’s internal structures to infection risk and scarring. Deeply penetrating cracks may cause damage to the delicate laminae (tissues that attach the hoof capsule to the coffin bones) and the lateral cartilages. These structures slope upwards from the wings of coffin bones and can cause sidebones when ossified.
Muir stated that horses’ feet are subject to a certain amount expansion and contraction. “As long the contraction and expansion are within the limits of what the hoof capsule is able to withstand, there will be no problem. Quarter cracks, however, are a sign of capsule dysfunction.
Muir suggested several reasons to avoid capsule dysfunction.
- Poor hoof quality and growth can be caused by poor nutrition, poor hygiene, inadequate exercise and sleeping in stalls. A combination of all these factors can lead to horse hoof problems, including thrush and white line disease.
- Moisture can cause the hoof wall to become soft. Horses with quarter cracks in their past might find it difficult to resist moisture.
- Limb conformation. Horses’ conformation can cause force to the ground, stressing, distorting and eventually damaging the hoof capsule. The hoof capsule that is distorted will be more susceptible to breaking down.
- Loading position and gait abnormalities due to conformational issues may cause hoof distortion. Blunt force trauma can also result from interference between feet or legs.
- Unbalanced trimming and shoeing. These can be caused by the above mentioned conformational issues or infrequent or irregular hoofcare.
It is important to evaluate whether our shoeing habits are long-lasting.Stuart Muir
Shoeing Strategies
Muir stated that different hoof problems can cause quarter cracks. Farriers and veterinarians should address each case separately. He said, “It’s crucial that we always seek to determine the root cause of these horses cracking and then try to make sure that they have a functional, healthy foot.”
A horse with a low (or clubby) foot, for example, will require a different approach to handling than one with a positive palmar angle. He said that the former might require more heel support while the latter may benefit from a composite or glue-on shoe to allow for the hoof capsule’s relaxation.
Muir stated that hoof perfusion (growth), is the farrier’s best friend when it comes to quarter cracks. Healthy growth is often linked to blood flow in the feet as well as genetics. This gives the farrier more foot and allows the crack to grow out. Muir displayed venograms, which are foot X-rays taken after contrast media was injected into the blood vessels. This indicates that wedging can reduce circulation and lead to hoof growth. He said, “.” He said that shoe prescriptions should be changed if the hoof capsule responds well to treatment or if there are other conditions (diseases or damage).
Muir shared his belief in the importance of shoeing the horse around the center rotation. This creates a 50/50 balance between the heel and toe of the shoe, which ensures that the horse’s heels remain well supported. This can reduce leverage, which could otherwise cause the crack to continue to split.
Muir stated that heart bar shoes were used by farriers and veterinarians for quarter cracks treatment for years. The shoes feature a bar at the heel that is attached to a plate over the frog. This allows the structure to distribute the load of the foot, which reduces stress and helps prevent cracking. Muir stated that there are now more options available, including fillers, impression materials and pads, as well as other bar shoes that could serve the same purpose. He said that the farrier’s comfort with the products will determine the best approach.
Crack Repair
Muir stated that farriers and veterinarians have more options for fixing cracks. These materials include fillers, Kevlar, Kevlar or another woven fabric patch, adhesives and stainless stitches. They are often used in conjunction with shoeing to support the hoof wall. To reinforce the wall, patching is done by using adhesive to attach fabric to the crack. To achieve the same result, you can use stainless steel sutures to close the crack.
He said that the hoof quality, crack depth and location will all play a role in deciding whether to use stitching or patching. Quarter cracks are often found in areas where the hoof wall is weak or thin. Otherwise, a crack would not have formed. Muir stated that stitching through the wall can be dangerous. Muir noted that he uses acrylic glue to fill pillars for stitching into hoof. He places the stitches through the filler on horses with thin hoof walls.
Do not discount a barefoot approach
Many of the horses Muir has worked on are sport horses. Their owners want them to be in training and wearing shoes. To allow the hoof capsule heal, it might be better to rest the horse, pull the shoes and manage the quarter crack barefoot. A case study was shared by the author about a hunter that, after months of shoeing with very limited results, saw significant improvement in his monthly performance when he went barefoot.
Take-Home Message
Quarter cracks can be serious and cause severe lameness. Because quarter cracks result from a variety of factors–ranging from hoof health to conformational abnormalities–veterinarians and farriers must take an individualized approach to treating them.
