Alopecia (hair loss) related to dilute coat color is a recognized condition in dachshunds.. The condition may affect any dilutely pigmented dog. This condition was previously known as Blue Balding Syndrome, Blue Doberman Syndrome, Congenital Alopecia, etc. Dilute individuals carry a recessive genotype of dd. The dachshund coat colors may include blue or fawn (isabella). CMA 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 tan areas retain a normal appearance. 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. There is no cure for CMA. Treatment is limited to controlling the scaliness and any associated pruritus with various shampoos or topical treatments.
The cause of CMA is not clearly understood. Microscopic examination of hairs of dilute individuals reveals that the pigment (melanin) forms large granules (macromelanosomes) which are rarely found in deeply pigmented hairs. In dilute individuals with normal appearing coats, these macromelanosomes are not grouped or clumped and cause no distortion of the cuticle (outer covering) of the hair. Dogs with CMA have many large groups or clumps of macromelanosomes which tend to distort the cuticle of the hair. It is hypothesized that this distortion of the cuticle causes the hairs to break easily, resulting in the short stubby hairs commonly found in affected individuals. It is further hypothesized that the rupture of the hair releases byproducts of pigment formation, which are toxic to the hair follicles. Regrowth of broken hairs is reduced because of damage to the follicles caused by these toxins. Why in some dilute dogs the macromelanosomes are clumped and in others they are not, is an interesting question at this time. The relationship between dilute pigment and hair loss is clear, but why are some dilute individuals unaffected? 50-80% dilute Dachshund are affected. A third allele (dl) which is associated with CMA has been proposed. While this is a long way from being proven, it could help explain why some dilute animals are unaffected. Dogs with a genotype dd would be normal coated dilutes, ddl would be intermediates (mildly affected?) and dldl would be CMA affected. A genotype of Ddl should represent deeply pigmented dogs which were carriers of CMA.