The currently accepted medical terminology for this condition is Color Dilution Alopecia (CDA). This condition may affect any dilutely pigmented dog, regardless of coat color. This condition develops in some, but not all dogs that have been bred for unusual coat colour, especially “fawn” (which is a dilution of a normally red or brown coat) or “blue” ( which is a dilution of the normal black and tan coat color).
CDA is an inherited type of follicular dysplasia.
This condition has also been known as : Blue or Fawn Doberman Syndrome, Fawn Irish Setter Syndrome, Blue Dog Disease, Blue Balding Syndrome, Blue Doberman Syndrome, Color Mutant Alopecia, and Congenital Alopecia.
Dobermanns – has the highest frequency of this condition. It occurs in 93 % of blues and 75 % of fawns.
Dilution is caused by irregularities in melanin transfer and storage.
The term Color Mutant Alopecia arose because dilutes were at one time mutations from the deep pigment occurring in wild canines. Dilutes are now a regularly occurring form of pigmentation in many breeds and have been for hundreds of years. The term mutation is therefore not applicable to dilute individuals. References to Doberman Pinschers or blue hair coats arose because the condition is common in blue individuals of this breed, but it is not limited to either blue dogs or Dobermans.
Alopecia means hairlessness. The affected dogs will have a poor, patchy coat that progresses to a widespread permanent hair loss. At the cellular level, there are abnormalities of the hair follicles and uneven clumping of pigment (melanin) granules in the hair shafts in affected areas.
CDA affected dogs are born with normal hair coats. The dilute (also known as Maltese) gene also appears in both mice and cats. In the mice and cats it is not associated with any abnormal coat conditions. Dilute individuals carry a recessive genotype of dd and are characterized by blue, bluish-grey, lavender or flesh-colored noses, lips and eye rims. The coat colors may include blue, fawn, blue-fawn, bronze, taupe or some variation of these. These dogs are usually easily distinguished from their deeply (non-dilute) pigmented counterparts. Deeply pigmented individuals carry a dominant genotype of Dd or DD and have black or liver noses, lips and eye rims. Coat colors may include black, red, red-fawn, liver or variations.
CDA is characterized by loss of hair from dilutely pigmented areas. Coats are normal at birth, and onset of hair loss usually begins between six months and three years of age. Hair loss usually begins along the dorsal midline (middle of the back) and often spares the head, tail and limbs. The pattern seems to vary from breed to breed. It has been suggested that darker colored (steel blue) individuals are less likely to be affected, may be less severely affected or may start to lose hair later in life than lighter colored dogs. This suggests that the severity of the disease may be related to the amount of dilution present. Deeply pigmented or white areas of coat are unaffected. In blue dogs with tan points (Yorkies and Dobermans) the tan areas retain a normal appearance.
In piebald (white spotted) individuals, the white areas are unaffected by the hair loss. The hair loss may be total or partial and any remaining hairs are usually sparse, rough and easily broken or removed. The skin in the affected areas is usually scaly and may occasionally develop bacterial infections. Pruritus (itching) is usually absent, unless a bacterial infection has set in.
Most dogs who develop this condition are born with (except for color) normal appearing coats. Symptoms generally develop in dogs 4 months to 3 years of age. As they grow and mature, they develop brittle hair, followed by patchy hair loss sometimes referred to as a ‘moth-eaten’ coat. Only the blue portions of the coat are affected. Other colored areas remain normal. The condition is incurable.
Breeding advice Affected dogs, their parents and siblings should not be used for breeding. The condition can be entirely avoided by the use of non-colour-diluted dogs in breeding programs.
Color Dilution Alopecia (CDA) has been recognized in dilute individuals of many breeds of dogs including:
3. Doberman Pinschers
4. Great Danes
5. Irish Setters
6. Italian Greyhounds
6. Standard Poodles
9. Yorkshire Terriers
10. Miniature Pinscher
11. Silky Terrier
13. Boston Terrier
15. German Shepherd Dog
16. Shetland Sheepdog
18. Bernese Mountain Dog
19. English Bulldog
Alopecia is a common and often frustrating problem in dogs. Alopecia may be strictly a cosmetic concern to the owner (especially if a show dog), or may indicate an underlying external or internal disease process.
Parasites, allergy, bacterial or fungal infection, hormonal disease/imbalances and congenital or genetic disorders of hair growth may all contribute to alopecia.
When evaluating a dog with alopecia, it is important to characterize the alopecia according to its age of onset (congenital or acquired), duration, location, pattern (focal, multifocal/patchy or diffuse/symmetrical), degree of pruritus and whether complete (no hair at all) or partial (stubble/broken hairs) alopecia exists.
It is also important to determine the relationship of the alopecia to the season of the year, vaccination date, medications, clipping, surgery, estrous cycle (whelping), and stress of illness or fever.
Certain breeds are predisposed to specific causes of alopecia
Signs of color dilution alopecia include hair loss and recurrent skin infection on the back. It can involve the whole body. The condition starts between the ages of six months and two years. Early hair loss occurs due to hair breakage, making it similar to structural follicular alopecia. It is important to treat the skin infections, and etretinate has been used to treat the hair loss