what are chestnuts on horses

Chestnuts on horses are callosities, which are harder fleshy growths found on the inner side of the leg above the knee on the foreleg and, if present, below the hock on the hind leg. They are sometimes compared to fingerprints in humans and vary in size and shape. Chestnuts are formed from small deposits of keratin that gather on the horses leg, and they feel oily and scaly to the touch. They are totally harmless and are used for identification purposes by some breed registries, which require photographs of them among other individual characteristics. Horse groomers often peel or trim off the outer layers of chestnuts for neatness, so their appearance is subject to change. The evolution of the horse involved a reduction in the number of toes to one, along with other changes to the ancestral equid foot, and the chestnut is thought to correspond to the wrist pad of dogs and cats. Alternatively, it may be a vestigial scent gland similar to those found in some deer and other animals.