The importance of color in the Border Collie depends primarily on the owner; owners of working dogs have historically cared little about the color of the dogs-only that the dog be able to perform his or her duties. Owners interested in entering conformation show rings need to pay more attention in order to present a winning dog, and dogs must meet the Border Collie breed standard of the sponsoring Kennel Club.
Traditionally speaking, Border Collies have been mostly black dogs with smaller patches of other color, but Border Collies do exist in a full range of colors. The AKC allows almost any color, but restricts white dominance. In keeping with tradition, old-school Border Collie owners have steered clear of red or white Border Collies-red for matters of superstition, and white because it was believed sheep didn't respond well to dogs of their color.
Superstitions continue to break down among working dog owners, and both red and white Border Collies are proving their working and herding abilities admirably. Newer generations are far less concerned with colors such as these.
On Genetics And Color
Breeders are noting more and more red Border Collies in the ranks of the breed today. This result is in part due to the widened acceptance of this color of Border Collie, and from the expression of genetics.
Both white and red colors in Border Collies are the result of genes that are recessive when placed against the more dominant brown and black genes. When a recessive white or red gene is paired with a dominant gene, the dominant gene is expressed. White alleles occur in different combinations which determine the amount of white that a Border Collie will have, ranging from none to completely white. Often, the white gains on the other colors over generations of breeding.
Thus, a white or red Border Collie is not a genetic anomaly, just a less common genetic expression, and dogs of this color are not defective in any way (that is, of course, provided good breeding has been attended to otherwise). There is one exception to this general statement in regards to white Border Collies who have been produced from the pairing of two "merle" dogs.
Merles should never be paired for breeding. Two merles have the ability to each contribute the merle gene. Normally a quarter of pups born to two merle parents will inherit two merle genes, and when they do, the pup may be blind, deaf, or both blind and deaf. These dogs can usually be identified by appearance-the pup will normally be mostly white with small merle spots. This is common knowledge among Border Collie breeders, and is completely avoidable as long as merles are not mated together (as they never should be). As long as you can be sure of the parentage of a white Border Collie, though, there is no reason for concern, and again, any good breeder will know the parents of their pups; one who doesn't isn't a person that you should buy a puppy from!
In the end, white and red are perfectly respectable, while less common, colors for Border Collies. Especially for those who prefer a unique look for their dog, a red or white Border Collie might just be the perfect collie fit!