Follicular dysplasia

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Four dogs affected with BHFD and one control littermate (in the middle) at the age of 1 week. Note the silver-grey instead of black colour in dark-haired patches[1]

Follicular dysplasia is a skin disease of dogs characterized by abnormal hair growth and consequent alopecia.

A variant of this condition is color dilution alopecia (black hair follicular dysplasia).

An hereditary form of follicular dysplasia is color dilution alopecia, characteristically seen in the Doberman, is caused by one or more mutations within or near the MLPH gene[2]. In these cases, permanent hypotrichosis, limited to the dorsolumbar region and sides of the trunk is seen. The hypotrichosis begins at approximately the age of 2 years and progresses slowly with no skin hyperpigmentation[3]. Other breeds are also affected such as the Boston Terrier.

Black hair follicular dysplasia (BHFD) is a variant form of color dilution alopecia which primarily affects the Munsterlander, Huntaway[4], Jack Russell Terrier[5], Papillon, Gordon Setter[6], Saluki[7] and Bearded Collie[8]. This condition is characterized by a specific pigmentation phenotype and sometimes accompanied by hair loss and recurrent skin inflammation[9].

Canine black hair follicular dysplasia is a rare disorder confined to black coat regions affecting bicolor or tricolor animals within the first few weeks of life[10]. Lesions are characterized by dull, dry, lusterless hair, hair fracture, hypotrichosis and scaliness[11]. An autosomal recessive mode of inheritance has been determined for the Large Münsterländer[12]. Histopathology is characterized by accumulation of melanin clumps within hair shafts, follicular lumina, root sheaths and hair bulbs. Hair shafts are irregular, bulging or replaced by keratinous debris.

A differential diagnosis would include seasonal flank alopecia, systemic lupus erythematosus, follicular parakeratosis and sertoli cell tumor.

Treatment may require broad-spectrum antimicrobials if microbial cultures reveals bacterial infection.

Melatonin has been shown to improve hair regrowth in the Boxer dog[13], and the use of etretinate, a synthetic aromatic retinoid, and niacinamide may also be of benefit.

References

  1. von Bomhard W et al (2006) Black hair follicular dysplasia in Large Münsterländer dogs: clinical, histological and ultrastructural features. Vet Dermatol 17(3):182-188
  2. Philipp U et al (2005) Polymorphisms within the canine MLPH gene are associated with dilute coat color in dogs. BMC Genet 6:34
  3. Moura E & Cirio SM (2010) Follicular dysplasia of the adult doberman pinscher. J Am Anim Hosp Assoc 46(2):143-147
  4. Munday JS et al (2009) Black-hair follicular dysplasia in a New Zealand Huntaway Dog. N Z Vet J 57(3):170-172
  5. Knottenbelt CM & Knottenbelt MK (1996) Black hair follicular dysplasia in a tricolour Jack Russell terrier. Vet Rec 138:475–476
  6. Selmanowitz VJ et al (1977) Black-hair follicular dysplasia in dogs. Journal of the American Veterinary Medical Association 15:1079–1081
  7. Hargis AM et al (1991) Black hair follicular dysplasia in black and white Saluki dogs: differentiation from color mutant alopecia in the Doberman Pinscher by microscopic examination of hairs. Vet Derm 2:69–83
  8. Drögemüller C et al (2007) A noncoding melanophilin gene (MLPH) SNP at the splice donor of exon 1 represents a candidate causal mutation for coat color dilution in dogs. J Hered 98(5):468-473
  9. Kim JH et al (2005) Color-dilution alopecia in dogs. J Vet Sci 6:259-261
  10. Selmanowitz VJ et al (1972) Canine hereditary black hair follicular dysplasia. J Hered 63:43–4
  11. Dunn KA et al (1995) Black hair follicular dysplasia. Veterinary Record 137:412
  12. Schmutz SM et al (1998) Black hair follicular dysplasia, an autosomal recessive condition in dogs. Can Vet J 39:644–646
  13. Rachid MA et al (2003) Concurrent follicular dysplasia and interface dermatitis in Boxer dogs. Vet Dermatol 14(3):159-166