Thehorse.com - http://www.thehorse.com/ViewArticle.aspx?ID=7630
Do your horse’s hooves have these healthy characteristics?
Much has been written about the equine foot, yet many of us know little about how it's really supposed to look and work. Sound horses don't all have the same size or shape feet (just like humans), and that fact often makes it more difficult to understand the healthy foot's form and function.
This means we can't use a one-size-fits-all approach to say what makes a healthy foot. We have to learn about how the horse's foot is built and how it works, and we must understand how individual variation changes the equation. With that understanding, we can look at our horses' feet and identify characteristics that are healthy, and those that hint at problems in the making.
Outside of the Healthy Foot
The healthy hoof wall is a semi-rigid, keratinized (nonsensitive) structure that protects underlying structures and supports weight along with the sole and frog. It has a hard, dense, naturally polished surface with distinct tubules that run straight (not flared) from the coronary band (at the hairline) to the ground. The wall should be intact, not cracked or chipped, and it should have a dense, tight tubular pattern. The toe is the thickest part of the wall and should be at least three-eighths of an inch thick in most mature breeds. It thins at the widest point of the foot and thickens again as it reaches the turning point at the heel.
Healthy adult hooves normally are wider at the ground than at the coronary band, but foals have feet that are narrower at the ground.
Growth rings, where they haven't been rasped off, provide valuable information on the health of the foot. They should be evenly spaced around the foot, indicating that toe and heel growth are equal (each ring shows about 30 days' growth). A narrow pattern in one area indicates slower growth due to reduced circulation; this could be from overloading as a result of poor conformation and/or balance, injury, or disease. (Note that slightly narrower growth rings on the medial or inner side of the foot are common due to asymmetrical loading from the horse's limbs being placed at the body's corners; this is not normally a cause for concern.)
Hoof angles are a function of conformation of external as well as internal structures, age, breed, load, growth rate, and environmental conditions. We'll get to the internal structures in a bit.
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