Alterations of the pituitary-ovarian axis in dogs with a functional granulosa cell tumor

Buijtels, J.J.C.W.M.; de Gier, J.; Kooistra, H.S.; Kroeze, E.J.B. Veldhuis; Okkens, A.C.

doi:10.1016/j.theriogenology.2009.06.031

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Volume 73, Issue 1 , Pages 11-19, 1 January 2010

Alterations of the pituitary-ovarian axis in dogs with a functional granulosa cell tumor

J.J.C.W.M. Buijtels
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
- Corresponding author. Tel.: +31302531682; fax: +31302518126.
J. de Gier
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
H.S. Kooistra
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
E.J.B. Veldhuis Kroeze
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
A.C. Okkens
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands

Received 19 December 2008; received in revised form 11 May 2009; accepted 22 June 2009. published online 12 October 2009.

Abstract

Information on the pituitary-ovarian axis in dogs with a granulosa cell tumor (GCT) is lacking. Therefore, we investigated the plasma concentrations of luteinizing hormone (LH) and estradiol before and after gonadotropin-releasing hormone (GnRH) administration in seven bitches with a functional GCT (GCT-total), of which three were intact (GCT-intact) and four had remnant ovarian tissue (GCT-ROT). The results of the GnRH stimulation test were compared with those in six anestrous and six ovariectomized bitches. The most noteworthy results were as follows. The basal plasma LH concentrations of the GCT-ROT bitches were higher (P<0.05) than those of the anestrous bitches. The increment in the plasma LH concentration after GnRH administration in the GCT-total bitches was lower (P<0.001) than the increments in both the anestrous and ovariectomized bitches. The basal plasma estradiol concentrations in the GCT-total bitches were higher (P<0.001) than those in the anestrous and ovariectomized bitches. In conclusion, the pituitary-ovarian axis is affected in bitches with a functional GCT and is characterized by relatively high plasma LH concentrations in GCT-ROT bitches and a subnormal LH response to GnRH stimulation in all GCT bitches compared with those in anestrous and ovariectomized bitches. The relatively high proportion of dogs with remnant ovarian tissue among the GCT bitches suggests a pathogenetic role for elevated gonadotropin secretion in the pathogenesis of GCT.