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INCREASING SOLE DEPTH: Finding The Right Balance

Investigating Sole Depth in Two Horses Using Infrared Thermal Imaging

The amount of sole protecting the Coffin Bone (P3) is an ongoing natural process that the horse has no control of. The hooves adapt, change and grow depending on a number of factors, often controlled by human intervention, be it for the good of the hoof or sometimes for the worse.

Horses with good sole depth will often be able to cope with variable ground conditions without a hitch. Depending on the working terrain, these horses may require shoeing or booting if the demands are too great, such as very rocky, slippery or unstable conditions. These horses rarely come up foot sore but may require exfoliation of the sole if the sole gets too thick; a sole that is too thick affects proper hoof mechanics including blood flow. Horses susceptible to thin soles are often tender on one or more hooves, may require regular shoeing or booting and/or hoof hardeners, and may have limited capacity for successful performance. Thin soles can as well affect hoof mechanics and blood flow.

What we do know about sole depth is that nature is always trying to get it right for each particular horse. Shedding soles and building up sole material are ongoing natural processes that occur to keep hooves as healthy as possible. But sometimes these processes are affected by +/- human intervention and environmental conditions, and sometimes they just need a helping hand to get to that ideal thickness.

Factors that influence sole depth include:

1. Genetics and Deformities: require ideal conditions, diet and trimming to encourage good growth.

2. Ground and Environmental Conditions: for example wet vs dry conditions, soft vs hard conditions, grass vs abrasive footings, winter (snow) vs summer (grass).

3. Stimulation: activity stimulates the sole by increased blood flow and through natural hoof mechanics (loading and unloading). Also, footings like sand, pea gravel, and gravel can stimulate sole building but it can also thin a sole if too abrasive for the quality of sole material.

4. Diet: this is a major pillar in horse health that is sometimes overlooked. If the hoof is well nourished and minerals are in good balance, then the sole and hoof have a really good chance of producing healthy material and maintaining quality. Improving hoof material may take months so it is not an “instant” process. Water, Quality Protein, Energy, Calcium, Sulfur, Manganese, Cobalt, Copper, Zinc, Selenium and Vitamins A, B, C, D and E are some important nutrients needed in correct amounts in the horse’s diet to maintain strong hooves and sole depth.

5. Quality and Appropriate Hoof Trimming and or Shoeing: If the horse’s hooves are trimmed appropriately for that horse then the healthy sole will continue to grow and increase depth, protecting the P3. However if too much material is removed, then the result is an “ouchy” horse that will require booting, shoeing, and/or hardeners. Sometimes it will take as long as two weeks to grow more sole so the horse can be comfortable again. If farrier practices are too aggressive the horse is subjected to cycles of growth and discomfort that defeats good sole depth maintenance.

6. Booting, pads and hardeners work to protect the delicate thin sole and promote growth, while protecting the new sole growth from abrasive forces of some footing materials. They also help to encourage more activity which again stimulates growth through increased blood flow and hoof mechanics.

7. Pathologies include laminitis, founder, obesity, thrush, navicular, etc. All can affect sole depth one way or the other. Some of these can cause toe-first landings that can impede sole growth, crushing material and restricting blood flow to the structures.

8. Behavioral Issues such as pawing the ground or gates can cause unnecessary wear on soles and increase chances of bruising to the hoof walls and soles.

While there are other influencing factors, these are the most common. When improving sole thickness one must consider ALL the factors and address each one where needed. For example if you provide a solid nutritional program but trimming practices are questionable then you will not be getting the results you hope to expect. All factors must work together, and monitoring needs to take place to ensure you are on the right track.

Earlier this year I purchased an Infrared Thermal Imaging Camera (Medical Grade) to help me understand more about my horses and my clients’ horses. At each 4 week trimming cycle I take images of the hooves. I took images for February, March and April. Because I live in Northern Ontario, I had snow on the ground still in February and most of March. By April the snow and ice were all gone. The track system the two horses are on have varying footings: mud, sand, light gravel, grass, clay, and their turnout barn with shavings. Both horses are on the same diet which is nutritionally complete and minerals are balanced.


Photo A: My older mare had thin soles during the winter/snow months (Feb and into March) but sole depth increased as soon as the snow was gone. The stimulation of activity plus the ground conditions were enough for more growth. There was never any tenderness despite the thinner soles during the winter. In the photos for this case the red indicates higher temps detected because of thinner soles (better heat transmission). It is normal to have red/higher temps in the collateral grooves and central sulcus. As sole material thickens it creates a thicker thermal insulation so the temps are lower (blue, green, yellow). All four hooves reacted the same way. This mare may be better off with booting during the winter months as added protection, and barefoot during the spring to fall months. Continued imaging and monitoring will confirm if this is the best route for this gal.

Photo B: My other mare reacted the opposite way for sole growth. She had thicker soles during the winter months (Feb and March). But as soon as the snow disappeared and she was subjected to the same footing materials and activity levels, there were more abrasive forces at work than her sole could handle and hence thinner soles resulted – at least that is my theory. The obvious symptom of a tender left front hoof left me scurrying to investigate the cause. The resulting images and palpitations were consistent with thinning soles. Boots and pads were immediately put on both fronts plus a hoof hardener product to maintain comfort, improve circulation and activity, and promote new sole growth again. This mare has been doing extremely well despite being a major founder case a few years ago due to PPID. She wears her boots intermittently but less so during the winter with the soft snow. Her PPID is well managed with medication and a specialized diet. This girl may be best off during the spring to fall to have her in boots more regularly, and less so during the winter. The application of the hoof hardener and sole depth results will also be monitored more closely moving forward.



Interested in taking the next step in your horse's nutrition? Do you need help in determining the best combination? Send an email to and share your story!


Jean Klosowicz, Equine Nutrition Consultant & Educator

Superior Equine Health and Nutrition Inc.

Bruce Mines, ON

fb: @SuperiorEquine


Healthy Horses. Happy Owners. Superior Results!

Superior Equine Health and Nutrition Inc. ~

The articles contained in this column are for the purpose of education and are not intended to take the place of proper veterinary care. They may be used in conjunction with such care to facilitate healing and maintain health of the horse.

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