Spaying-induced coat changes: the role of gonadotropins, GnRH and GnRH treatment on the hair cycle of female dogs.
Although spaying can result in qualitative hair coat changes in dogs, the influence of spaying on the hair growth cycle has never been described. The study aims were to examine the effect of spaying and gonadotropin-releasing hormone (GnRH) treatment on canine hair coat, cycle stages of hair follicles, plasma gonadotropin concentrations and mRNA transcription of luteinizing hormone (LH) and GnRH receptors in hair follicles. Fifteen female dogs were examined before and 1 year after spaying and 24 spayed dogs before and after GnRH treatment. Spaying resulted in increased plasma gonadotropin concentrations and increased anagen : telogen ratio of hair follicles, but only 20% of the dogs developed coat changes. No differences were found in mRNA transcription of LH and GnRH receptors. GnRH treatment resulted in reduced plasma gonadotropin concentrations and improvement of coat changes in 79% of patients. This was associated with an increase in catagen hair follicles without changes in the anagen : telogen ratio. The present study demonstrated that spaying had an effect on the anagen : telogen ratio of hair follicles. Spaying-induced coat changes did not correlate with the anagen : telogen ratio. GnRH treatment reduced gonadotropin concentrations and reversed coat changes in some dogs, but had no effect on the hair growth cycle other than increasing the number of catagen hair follicles. A weak positive correlation between the plasma LH concentration and the anagen : telogen ratio was noted; however, our data did not suggest a direct receptor-mediated hormonal effect on the hair follicle. The present study did not identify the pathomechanism of spaying-induced coat changes.
Reichler
Iris Margaret
IM
Section of Small Animal Reproduction, Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland. ireichler@vetclinics.unizh.ch
Welle
Monika
M
Eckrich
Christine
C
Sattler
Ursula
U
Barth
Andrea
A
Hubler
Madeleine
M
Nett-Mettler
Claudia S
CS
Jöchle
Wolfgang
W
Arnold
Susi
S
D000818:Animals; D002455:Cell Division / Q000187:drug effects*; D004285:Dogs; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology* / Q000627:therapeutic use*; D006062:Gonadotropins / Q000097:blood; D006197:Hair / Q000254:growth & development; D018859:Hair Follicle / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development; D007986:Luteinizing Hormone / Q000097:blood; D010052:Ovariectomy / Q000009:adverse effects / Q000379:methods / Q000662:veterinary*; D011966:Receptors, LHRH / Q000378:metabolism; D012880:Skin Pigmentation
D006062:Gonadotropins; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone