Canis ISSN: 2398-2942

Skin: alopecia X

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

Contributor(s): David Scarff, Rosanna Marsella, Prof Linda Frank

Introduction

  • 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.

Pathogenesis

Etiology

  • 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

General
  • Breed.

Pathophysiology

  • 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.

Timecourse

  • Months to years.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

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