Clinical observation and points and diagnostic tests for non-inflammatory alopecia

 Breed: Predisposed breed?

 Color of hair coat and eyes: Dilute color (blue, fawn) or not?

 Quality of hair coat: Puppy coat? Dull and dry hair?

 Onset age: Congenital or tardive?

 Distribution of alopecia: Color-linked or non-color-linked? Symmetrical?

 Occurrence: seasonal or non-seasonal?

 Pigmentation: Alopecic skin is pigmented or not?

 General findings: Any other signs?

 Laboratory tests: Hematology, biochemistry, hormonal test

 Skin scrapings: Scabies, Demodex, dermatophytosis

 Stamp preparation: Malassezia, bacteria, mycosis

 Plucked hair examination by microscopy: Anagen or telogen hair? Aggregation of melanin within a hair shaft?

 Biopsy: Atrophy or hypertrophy of epidermis? Atrophic hair follicles? Dystrophic hair follicles? Flame follicles? Cystic hair follicles and follicular keratosis? Aggregation of melanin in hair shafts or epidermis?

Alopecia due to hair cycle abnormality without follicular dysplasia

1) Hyperadrenocorticism

 Dog breeds: Any breeds

 Onset age and sex: Usually middle aged to older dogs

 Cutaneous signs: Hair loss of trunk, skin atrophy, calcinosis cutis

 General signs: Polyuria and polydypsia, polyphagia, muscle weakness, obesity, pot-bellied appearance

 Laboratory findings: Leukocytosis with an increase in the number of multinucleated neutrophils, lymphopenia, eosinopenia, elevated ALP level

 Diagnosis: Signalment, history, clinical signs, ACTH stimulation test, dexamethasone suppression test, CT/MRI

 Therapy: Trilostane, op'-D, D, D, ketoconazole

2) Hypothyroidism

 Dog breeds: Predisposed to middle to large breeds, although any breeds may be affected

 Onset age and sex: Often four to eight years old: no difference between male and female

 Cutaneous signs: Hair loss often with pigmentation on nose, trunk, and tail

 General signs: Lethargy, intolerance to exercise, cold skin, weight gain without polyphagia

 Diagnosis: History, clinical signs, abnormal laboratory findings including moderate non-regenerative anemia, elevated total cholesterol, total T4, free T4 and TSH levels, TSH stimulation test

 Therapy: Supplementation of thyroxin

3) Alopecia X of Nordic breeds

 Dog breeds: Nordic breeds such as Pomeranian, Spitz, Samoyed

 Onset age and sex: Two to five years old, most frequently between two to four years old, male

 Clinical findings: Hair loss starts from thighs and extends to trunk with or without pigmentation. Puppy coats may appear before the hair loss occurs. Hair on the head and extremities is conserved. No abnormality other than hair loss is observed.

 Diagnosis: Signalment, history, clinical findings and exclusion of other possible causes such as hypothyroidism and hyperadrenocorticism

 Therapy: As this disease is basically a cosmetic problem, therapy that may cause severe side effects should be avoided

 Castration: Hair regrowth is expected after castration: however, recurrence after one year is possible

 Melatonin is reported to be effective in 33% of patients. Melatonin is inexpensive and safe and the dose is 3 mg/head or 6mg/head for two to three months

 Trilostane is regarded as the most effective and safe drug for this disease: however, it is very expensive. Four to 6 mg/kg of Trilostane is administered orally once a day for two months: Conduct ACTH stimulation test for every two months.

Alopecia due to structural abnormality of hairs (Follicular dysplasia syndrome)

Color-linked

1) Black hair follicle dysplasia

 Dog breeds: Bearded collie, Border collie, Basset hound, Papillion, Saluki, Beagle, Jack Russell terrier, Cocker spaniel or dogs with bicolor or tricolor coats containing black hair

 Onset age: Normal hair coat at birth. Black hair is exclusively affected by four weeks and the development of this condition stops at six to nine months old after most of the black hair is lost.

 Clinical signs: Loss of black hair in bicolor or tricolor-coated dogs

 Trichogram: Clumped melanin with the destruction of hair shaft, but is less intense than that of color dilution alopecia

 Treatment: Melatonin at 3-6 mg/head may be effective

2) Color dilution alopecia

 Diluted colors of black and brown are blue and fawn, and those color dilutions sometimes are lead to hair abnormality

 Dog breeds: Doberman pinscher, dachshund, Great Dane, Whippet, Italian Greyhound, etc.

 Onset age: Hair loss in dogs with strongly diluted hairs starts as early as six months of age. Alopecia in weakly diluted dogs starts at two to three years old.

 Clinical signs: Hair loss in diluted color area: later onset than black hair follicle dysplasia

 Trichogram: Numerous melanin clumping in hair shaft with the destruction of hairs

Non-color linked

1) Follicular dysplasia

 Dog breeds: Siberian husky, Doberman pinscher, Miniature pinscher, Airedale terrier, Boxer, English bulldog

 Onset age: Depend on a breed

 3 to 4 months old; Siberian husky

 1 to 4 years old; Doberman pinscher, Miniature pinscher

 2 to 4 years old; Airedale terrier, Boxer, English bulldog

 Clinical signs: Non-seasonal, non-color-related, symmetrical alopecia caused by follicular and/or hair dysplasia. SH: Primary hairs is lost and skin color changes to dark red.

 DP, MP: Hair loss in trunk extending to the back. AT, Boxer, EB: Hair loss confined to the trunk.

 Trichogram: Melanin clumping and breaking of the hair

 Treatment: Melatonin at 3 to 6 mg/head

2) Seasonal flank alopecia

 Dog breeds: Airedale terrier, English bulldog, Boxer, Scotch terrier

 Clinical signs: Nonpruritic, well-demarcated, usually bilaterally symmetrical alopecia of flanks, sometimes of nose, base of tail and ears. The alopecic skin area is often deeply pigmented. Alopecia occurs seasonally, starting between November and March, and ending after three to eight months.

 Histopathology: Dysplastic hair follicles containing keratin: melanin clumping and breaking of hair

 Diagnosis: Breeds, history, clinical findings and histopathology

 Treatment: Melatonin at 3 to 6 mg/head, bid

3) Pattern baldness

1.  Pinnal alopecia in male Dachshund

a.  Breed: male, rarely female Dachshund

b.  Onset age: 6 to 9 months old

c.  Clinical signs: Pinnal hair loss and normal coats

2.  Postauricular, ventrum and caudomedial hair loss

References

1.  Carlotti DN: Canine hereditary black hair follicular dysplasia and colour mutant alopecia; Clinical and histopathological aspects. Adv Vet Dermatol, 1:43-46, 1992

2.  Schmutz SM, Moker JS, Clark EG et al.: Black hair follicle dysplasia, an autosomal recessive condition in dogs. Can Vet J, 38: 644-646, 1998

3.  Knottenbelt CM, Knottenbelt MK: Black hair follicular dysplasia in a tricolor Jack Russell terrier. Vet Rec, 139: 475-476, 1996

4.  Laffort-Dassot C, Beco L, Carlotti DN: Follicular dysplasia in five Weimaraners. Vet Dermatol, 13: 253-260, 2002

5.  Schmeitzel LP: Alopecia X of Nordic breeds. Proceeding of the AAVD and ACVD, Maui, 131-138, 1999