This condition is seen in dogs with a dilute coloured coat and occurs in up to 90% of blue Dobermanns, and 75% of fawns. This condition also occurs in other breeds where breeding for colour dilute individuals occurs, although it does not tend to be seen at such high rates as in the Dobermann, and prevalence rates can vary depending on the breed. Colour dilute Weimeraners do not seem to be affected at all. The reason for the amount of variation between colour dilute animals of different breeds is not known. The main breeds affected (other than the Dobermann) include the Boston terrier, the Chihuahua (blue), Great Dane (blue), Dachshund (blue), Miniature Schnauzer, Miniature Pinscher (blue), Shetland Sheepdog (blue), Whippet (blue), Standard Poodle (blue), Yorkshire Terrier (grey/blue), Irish Setter (fawn) and the Bernese Mountain Dog.
Colour dilution alopecia is a type of follicular dysplasia, and only occurs when colour dilution is present. A blue coloured animal is the colour dilute form of the normal black and tan colouration, and fawn is the colour dilute form of the normal red colouration. It is thought that there is a defect in the regulation of melanisation (pigmentation) and the structure of the hair cortex, although the underlying genetic defect is not fully understood. Affected animals are born with normal hair coats, but usually signs will be seen between 6 months and 2 years of age, when the hair will begin to break, and patchy alopecia (hair loss) occurs. This usually starts on the back, and will progress to widespread hair loss wherever there is light coloured hair. The skin becomes dry and scaly, and is prone to infections. Hair that is lost will not grow back. Affected dogs are also susceptible to sunburn and cold.
There is no cure for this condition. Diagnosis is confirmed with skin biopsy, which will show characteristic changes when assessed by an experienced veterinary dermatopathologist. Treatment is symptomatic, using antiseborrhoeic shampoos and oil rinses, moisturisers and antibiotic therapy or antiseptics for secondary infections.