The Tail of the Shetland
The tail is a good indicator of whether or not a particular sheep is a purebred Shetland. The Shetland is a member of the European short-tailed race of sheep and it exhibits a wool covered, fluke-shaped tail that is broad at the base and tapers to a flattened hairy tip. Length is not as important as shape, but the tail is seldom over 6 inches long with the norm being about 4 to 5 inches.
It is consistently composed of 13 vertebrae as opposed to 20 or more in long-tailed sheep.