F12 HISTOPATHOLOGY FEATURES OF A CANINE SYNDROME CHARACTERISED BY ALOPECIA AND ABNORMALITY OF STEROIDOGENESIS

^1,2Cerundolo R., ²Lloyd D.H., ³Rest J.R. ¹Faculty of Veterinary Medicine, Naples, Italy, ²The Royal Veterinary College, London, ³Rest Associates, Cambridge, UK

A syndrome characterised by progressive truncal hair loss and cutaneous hyperpigmentation has been recognised affecting middle-aged dogs. Alopecic animals show abnormalities of steroidogenesis with increases in both the serum concentrations of 17-hydroxyprogesterone pre- and/or post-ACTH stimulation, and the urinary cortisol/creatinine ratios.

A group of 24 affected dogs (15 Pomeranians, 4 chows, 2 Keeshonds, 2 miniature poodles, and 1 samoyed) was sampled and cutaneous biopsy punch specimens were collected, under local anaesthesia, by from alopecic (n: 47) and clinically normal (n: 16) hairy skin.

Histology of cutaneous specimens from alopecic areas showed superficial and follicular infundibular hyperkeratosis, sometimes with comedone formation, with catagenisation or telogenisation of hair follicles leading to loss of some follicles.

Hair follicles with trichilemmal keratinisation (flame follicles) seem to be a feature of this syndrome in which abnormality of steroidogenesis may play a role in the prolonged/permanent catagen/telogen phase.

These animals may offer a model to further study mammalian steroidogenesis and its relationship with hair follicle development. Similarities with congenital adrenal hyperplasia in man are likely. The involvement of cutaneous receptors of intermediate hormones of steroidogenesis, is also possible as hair loss seems to only affect certain areas of the body surface.