Skin: alopecia X in Dogs (Canis) | Vetlexicon
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Skin: alopecia X

ISSN 2398-2942

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Synonym(s): Adult onset growth hormon deficiency; adrenal sex hormone imbalance; hyposomatotropism in the mature dog; pseudocushings syndrome; congenital adrenal hyperplasia-like syndrome; castration responsive dermatosis


  • Rare dermatosis, probably identified as 'growth hormone-responsive dermatosis' in the past. Also known as Adrenal sex hormone imbalance. However is now common in certain breeds, eg Pomeranians in the US.
  • Cause: unknown.
  • Signs: bilaterally symmetrical truncal alopecia often with hyperpigmentation of the skin.
  • Diagnosis: signs, histopathology, ruling out other endocrine diseases such as hypothyroidism and hypercortosolemia.
  • Treatment: neutering, if intact. Chemotherapy options include melatonin - mitotane, trilostane, or benign neglect.
  • Prognosis: good for health since this is a cosmetic disease but poor for permanent hair regrowth.

Presenting signs

  • Bilaterally symmetrical alopecia over frictional areas of tail, caudal thighs, ventral abdomen, cervical area and lateral trunk; head and extremities usually spared. Usually affecting flanks.
  • Dull, dry coat +/- scaling.
  • Truncal primary hairs lost at same time as hair in frictional areas giving the remaining coat a 'puppy-like' appearance.
  • Hyperpigmentation in alopecic areas.
  • Tufts of hair regrow at sites of skin biopsy or trauma.
  • Coat color may darken or lighten, with irregular streaks.
  • Tufts of hair regrow at sites of skin biopsy or trauma.

Age predisposition

  • Usually 1-3 years old, but may be any age from 1-10 years.
  • Over 8 years old.

Breed/Species predisposition



  • Etiology is unknown.
  • Current research is focusing on genetics and hair follicle receptors.
  • It is likely that there is an inhibition of anagen initiation or prolongation which could be multifactorial.

Predisposing factors

  • Breed.


  • Poorly understood condition, etiology and pathogenesis not known.
  • Hormonal alterations reported could be normal for those breeds and may not reflect pathophysiology of the disease.
  • May be hair cycle arrest causing alopecia which coincidentally responds to GH supplementation. GH is a known stimulator of anagen.
  • The presence of mild hyperadrenocorticism might explain response to mitotane in some cases although response to mitotane does not generally correlate with cortisol concentrations.


  • Months to years.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Frank L A, Donnell R L, Kania S A (2006) Oestrogen receptor evaluation in Pomeranian dogs with hair cycle arrest (Alopecia X) on melatonin supplementation. Vet Dermatol 17 (4), 252-258 PubMed.
  • Frank L A (2005) Growth hormone-responsive alopecia in dogs. JAVMA 226 (9), 1494-1497 PubMed.
  • Shibata K, Koie H, Nagata M (2005) Clinicopathologic and morphologic analysis of the adrenal gland in Pomeranians with non-illness alopecia. Jap J Vet Dermatol 11 (3), 115-120 J-STAGE.
  • Cerundolo R, Lloyd D H, Persechino A, Evans H, Cauvin A (2004) Treatment of canine Alopecia X with trilostane. Vet Dermatol 15 (5), 285-293 PubMed.
  • Frank L A, Hnilica K A, Oliver J W (2004) Adrenal steroid hormone concentrations in dogs with hair cycle arrest (Alopecia X) before and during treatment with melatonin and mitotane. Vet Dermatol 15 (5), 278-284 PubMed.
  • Frank L A, Hnilica K A, Rohrbach B W, Oliver J W (2003) Retrospective evaluation of sex hormones and steroid hormone intermediates in dogs with alopecia. Vet Dermatol 14 (12), 91-97 PubMed.
  • Takada K, Kitamura H, Takiguchi M, Saito M, Hashimoto A (2002) Cloning of canine 21-hydroxylase gene and its polymorphic analysis as a candidate gene for congenital adrenal hyperplasia-like syndrome in Pomeranians. Res Vet Sci 73 (2), 159-163 PubMed.
  • Rijnberk A, Van Herpen H, Mol J A & Rutteman G R (1993) Disturbed release of growth hormone in mature dogs; a comparison with congenital GH deficiency. Vet Rec 133 (22), 542-545 PubMed.
  • Schmeitzel L P (1990) Sex hormone-related and growth hormone-related alopecias. Vet Clin North Am Small Anim Pract 20 (6), 1579-1601 PubMed.
  • Schmeitzel L P & Lothrop C D (1990) Hormonal abnormalities in Pomeranians with growth hormone responsive dermatosis. JAVMA 197 (10), 1333-1341 PubMed.
  • Lothrop C D Jr. (1988) Pathophysiology of canine growth hormone responsive alopecia. Comp Cont Ed Pract Vet 10 (12), 1346-1349 VetMedResource.
  • Scott D W & Walton D K (1986) Hyposomatotropism in the mature dog; a discussion of 22 cases. JAAHA 22 (4), 467-473 Eureka Mag.

Other sources of information

  • Frank L A (2009)Canine alopecia X.In:Hair Loss Disorders in Domestic Animals. L Mechlenburg, M Linek, DJ Tobin, eds.Wiley-Blackwell: Ames, Iowa, p. 148-155.
  • Schmeizel L Pet al(1995)Congenital adrenal hyperplasia-like syndrome.In:Current Veterinary Therapy XII. Eds: Bonagura J D & Kirk R W. Philadelphia: W B Saunders Co.
  • Schmeizel L P & Parker W (1993)Growth hormone and sex hormone alopecia.In:Advances in Veterinary Dermatology - Volume 2.New York: Pergamon Press. Eds: Ihrke P Jet al. pp 451.
  • Rosenkrantz W M and Griffin C E (1992)Lysodren therapy in suspect adrenal sex hormone dermatosis.Proceedings World Congress Veterinary Dermatology2, 121.
  • Rosser E J (1989)Castration responsive dermatosis in the dog.In:Advances in Veterinary Dermatology, Volume 1. Eds: von Tscharner C & Halliwell R E W. London: Bailliere Tindall.
  • Rosser E J (1987)Growth hormone-responsive dermatosis versus castration responsive dermatosis.Derm Dialogue.
  • Baker K (1986)Hormonal alopecia in dogs and cats.In Pract8(2), 71-78.