<P> The chestnut, also known as a night eye, is a callosity on the body of a horse or other equine, found on the inner side of the leg above the knee on the foreleg and, if present, below the hock on the hind leg . It is believed to be a vestigial toe, and along with the ergot form the three toes of some other extinct Equidae . Darren Naish dissents from this belief, noting that the chestnut is "not associated with the metacarpus or metatarsus, the only places where digits occur ." </P> <P> Chestnuts vary in size and shape and are sometimes compared to the fingerprints in humans . For purposes of identification some breed registries require photographs of them among other individual characteristics . However, because chestnuts grow over time and horse grooms often peel or trim off the outer layers for neatness, their appearance is subject to change . </P>

Why do horses have chestnuts on their legs
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