Are dapples a sign of horse health?

You sometimes hear it said that a dappled coat means a healthy horse. Is this true?

Sort of.

A dappled coat on a grey horse is caused by the particular pattern in which the grey fades with age.

A dappled coat on a non-grey horse indicates that the horse has a genetic predisposition to produce dapples. However, these dapples are brought out more by regular grooming and good health. Also, dapples are not visible (although the genetics may be present) on black horses.

So, yes, a horse with dapples is healthy and has a good coat. However, not all horses that are healthy and have good coats have dapples.

This bay horse illustrates the point quite nicely - the top half of his body has visible dappling, whilst the lower half is plain. His genetics are allowing dapples to express only on part of him. Image source
Лена via Wikimedia Commons.