If your dog has a multicolored coat then it may be susceptible to a rare condition known as Black Hair Follicular Dysplasia, or BHFD. A hereditary disorder carried through recessive genes, BHFD can appear in any purebred or crossbreed dog with a multi-colored coat. An as-yet-unidentified genetic defect in the skin pigment (melanin) and in the hair shaft formation is believed to be the cause. This condition causes the black or dark-haired portions of the coat to fall out when the animal is still a puppy or young dog, leaving behind bare skin. In the early stages, the pup's dark hair will gradually fade and take on a washed-out, gray or bluish cast. These darker areas of skin are eventually left completely bald and may be covered with lesions, pimple-like pustules and/or dry, scaly skin. At the same time that all these symptoms are occurring, the dog's adjacent, light-colored fur remains normal. While the hair loss is usually permanent, there usually are no other serious effects on the dog's general health. A few animals may have an increased vulnerability to bacterial infections, but this has not yet been definitively proven. Most affected puppies appear normal at birth, but begin losing their dark hair when they're about four weeks old. The loss of dark-pigmented hair continues until the dog's darker patches are completely bald, usually by eight to nine months of age. The coat on a dog's body is generally affected more than the fur on the animal's head and neck.
Any dog with a multi-colored coat that also carries the defective gene can end up with BHFD. Breeds most often affected include: Airedale Terriers, Bassett Hounds, Curly-Coated Retriever, English Bulldogs, Irish Water Spaniel, Malamutes, Papillons, Portuguese Water Dogs, Schipperkes, Siberian Huskies, and Staffordshire Terriers. Hair loss in most of these animals occurs at a young age, but in some breeds, notably Doberman Pinschers, Irish Water Spaniels, Portuguese Water Dogs and Curly-Coated Retrievers, the disorder does not produce symptoms until the dog is between one and four years age, rather than during puppyhood. Also, in these animals, the hair loss is usually concentrated around the dog's lower back.
In yet another variation, seen mostly in Airedale Terriers, English Bulldogs and Staffordshire terriers, the hair loss begins between two to four years of age, and spreads over the back and sides in a saddle-like pattern. With these animals, the hair may regrow and then be lost again in a cyclical pattern.
There is a DNA test that can identify dogs that carry the gene, which is obviously useful in preventing the disease from being spread to a new generation. Meanwhile, there is no cure for BHFD, and changes in the dog's coat are usually permanent. In some cases, special shampoos and fatty acid supplements are prescribed to treat dry, scaly skin. Sometimes dogs with BHFD also develop skin infections, which are treated with antibiotics.