Some border collies may also have single-color coats. Eye color varies from brown to blue, and occasionally eyes of differing color occur; this is usually seen with merles. The ears of the border collie are also variable — some have fully erect ears, some fully dropped ears, and others semi-erect ears (similar to those of the rough collie). Some border collies may also have single-color coats. Eye color varies from brown to blue, and occasionally eyes of differing color occur; this is usually seen with merles. Breed standards state that its tail must be slightly curved and must stop at the hock. 'Meet Piper, the Airport K-9 Wildlife Control Dog Who Keeps Runways Safe'.
single-color coats.|must stop at the hock. single-color|tail must be slightly curved and must stop at the hock. single-color coats.|tail must be slightly curved and must stop at the hock.
single-color coats.|must stop at the hock. single-color|tail must be slightly curved and must stop at the hock. single-color coats.|tail must be slightly curved and must stop at the hock.