Canine hereditary black hair follicular dysplasia

Four Large Münsterländer cross-bred dogs affected with black hair follicular dysplasia (BHFD) and one unaffected control littermate were observed, and skin was sampled weekly over the first 19 weeks of life. Affected dogs were born with silvery grey hair, a consequence of melanin clumping in the hair shafts. Hair bulb melanocytes were densely pigmented, and contained abundant stage IV melanosomes but adjacent matrix keratinocytes lacked melanosomes. Melanin clumping was not prominent in epidermal melanocytes in the haired skin but occurred in the foot pads. Follicular changes progressed from bulbar clumping, clumping in the isthmus/infundibulum and finally to dysplastic hair shafts. Alopecia developed progressively in pigmented areas. Silver-grey hair, melanin clumping, accumulation of stage IV melanosomes within melanocytes and insufficient melanin transfer to adjacent keratinocytes are also classic features of human Griscelli syndrome. The underlying cause in Griscelli syndrome is a defect of melanocytic intracellular transport proteins leading to inadequate and disorganized melanosome transfer to keratinocytes with resultant melanin clumping. In view of the correlation in the phenotype, histology and ultrastructure between both disorders, a defect in intracellular melanosome transport is postulated as the pathogenic mechanism in BHFD.

Section: Discussionsupporting

confidence: 42%

Section: Introductionmentioning

confidence: 99%

Black hair follicular dysplasia in Large Münsterländer dogs: clinical, histological and ultrastructural features

Bomhard¹,

Mauldin²,

Schmutz

et al. 2006

“…BHFD in dogs was first described in 1972 as alopecia that is confined to black regions of the hair coat 51,125 . It has since been reported in a variety of breeds such as Bearded collie, Saluki, Border collie, King Charles spaniel, Jack Russel terrier, and Gordon setter 126–134 .…”

Section: Congenital Alopecia In Domestic Animalsmentioning

confidence: 99%

An overview on congenital alopecia in domestic animals

Mecklenburg¹

2006

Alopecia, that is, lack of hair in any quantity, is a frequent complaint of pet owners. Although mostly acquired, rare congenital forms of alopecia exist that are associated with abnormalities in hair follicle morphogenesis. Congenital alopecias can result in changes in quality or quantity of hair follicles and the hair fibres produced by them. They vary in terms of clinical presentation and mode of inheritance. Histopathology is usually needed in order to differentiate between a reduced number of otherwise normal hair follicles and qualitative hair follicle abnormalities. Although our understanding of the molecular mechanisms that drive hair follicle morphogenesis in mice and humans has significantly increased during the last decade, still very little is known about congenital alopecias in domestic animals. Because of their rarity and the general lack of knowledge about their pathophysiology, classification of congenital alopecias in domestic animals is still unsatisfactory. This article reviews hair follicle morphogenesis and its most important molecular mechanisms, and it discusses the various forms of congenital alopecia occurring in domestic animals that have been described in the literature, differentiating between hair follicle aplasia, hair follicle dysplasia (i.e. defects associated with hair follicle development and defects associated with hair shaft formation), and neuroectodermal dysplasias, the latter involving the hair follicle pigmentary system.

“…Colour dilution alopecia has been reported in colour dilute individuals of many breeds: Doberman, 2,4–10 Yorkshire Terrier, 2,8,11–15 Miniature Pinscher, 2,7 Great Dane, 4,5,8 Whippet, 4,5,8 Italian Greyhound, 2,8,16 Saluki, 8,12 Chow‐chow, 5,8 Smooth‐haired Dachshund, 4,5,8 Wire‐haired Dachshund, 3 Silky Terrier, 17 Boston Terrier, 18 Newfoundland, 18 Bernese Mountain Dog, 18,19 Shetland Sheepdog, 18,19 Schipperke, 18,19 Chihuahua, 2,7 Poodle, 2,6,8 Irish Setter 4,5,8 and cross‐breed 20 . Black hair follicular dysplasia has been reported in young bicoloured or tricoloured animals of the following breeds: Dachshund, 6 Papillon, 6 Saluki, 21,22 Bearded Collie, 23 Cavalier King Charles Spaniel, 24 Border Collie, 24,25 Beagle, 18,19 Basset Hound, 18,19 Cocker Spaniel, 2 Pointer, 2 Gordon Setter, 2 Schipperke 18 and cross‐breed 26,27 …”

Section: Colour‐linked Follicular Dysplasiasmentioning

confidence: 99%

“…Clinical signs consist of alopecia or progressive hypotrichosis in a young animal of predisposed colour and breed. Tan areas are spared in colour dilution alopecia and only black areas are affected in black hair follicular dysplasia 18,19,28 . Hair examination shows numerous large melanin clumps in the cortex and medulla of hairs from the affected area and defects and fractures of the hair cuticle 3,9,21,29,30 .…”

Section: Colour‐linked Follicular Dysplasiasmentioning

confidence: 99%

Follicular dysplasia in five Weimaraners

Laffort-Dassot

Beco

Carlotti

2002

This study evaluated the clinical and histopathological features and results of light and electron scanning microscopy assessments of follicular dysplasia in five Weimar Pointers. The data were compared with those obtained in three normal Weimaraners. In our study, this dermatosis affected young adults that showed progressive alopecia of the trunk (head and limbs were spared) associated with recurrent folliculitis/furunculosis. Exclusion of other dermatoses and the presence of histopathological lesions and hair shafts abnormalities seen in light and/or scanning electron microscopy similar to colour dilution alopecia led to the diagnosis of follicular dysplasia. The lesions we observed are the same as those described previously in colour dilution alopecia, but they were less pronounced in all our samples.