Some American pit bull fanciers might prefer a red-nose or blue-nose specimen, but these are not different breeds. The canines in question do have red or bluish noses to match their red or blue coat colors. The red-nose pit bull has a much longer history than the blue-nose version. Until recently, the latter was relatively rare.
Pit Bull Genetics
The American Dog Breeders Association, which promotes and registers purebred pit bulls, notes that genetic research into coat color has not been done with the breed, since historically these dogs were not bred for color. However, in recent years the red-nose and blue-nose pit bull have become fashionable. Genetic coat research has been done with a similar breed, the American Staffordshire terrier. The ADBA states that the blue coloration results from a homozygous recessive gene mutation. The red-nose dog also results from recessive genetic traits.
Nose and Breed Standards
The United Kennel Club registers American pit bulls. Under UKC standards, the nose is "large with wide, open nostrils," but any color is acceptable. The American Kennel Club registers American Staffordshire terriers, a breed often used synonymously with pit bulls. However, the AKC standards, adopted in 1936, clearly state the nose of a "Staffy" is "definitely black."
Red-Nose Pit Bulls
Red-nose pit bulls date back to a 19th century Irish line of fighting dogs. Red pit bulls appeared to have the fighting advantage, so dogs of this color were inbred to promote ferocity. Constant inbreeding of the recessive red coloration led to dogs with red noses and paw pads. According to the Proper Pit Bull website, the AKC deplored dog fighting. One reason the Staffy standard so strictly prohibits nonblack noses was to keep these genes out of the breed. Today's red-nose pit bulls are not especially aggressive, according to the PPB. They are simply dogs with red noses.
Blue-Nose Pit Bulls
Blue-nose pit bulls descend from a relatively small genetic pool. Technically, blue results from black color dilution. Since the blue coloration is recessive, breeders sometimes must breed closely related dogs to create blue puppies. Blue coloration in various breeds leads to skin and health issues. It's not uncommon for blue dogs to suffer from severe hair loss from a young age. These recessive genetics can cause immune-related problems, as well as vision and hearing loss.