title: The pituitary-ovarian axis in dogs with remnant ovarian tissue.
abstract: It can be difficult to confirm the presence of remnant ovarian tissue (ROT) in bitches that are presumed to be ovariohysterectomised. A GnRH stimulation test can be used to distinguish ovariectomised bitches from those in anoestrus, but it is uncertain whether the GnRH-induced changes in plasma LH and oestradiol concentrations that occur in intact bitches also occur in ROT-bitches. We report here eighteen ROT-bitches and compare the results of GnRH stimulation tests with those of six ovariectomised and six bitches in anoestrus. The basal (n = 17) and/or GnRH-stimulated (n = 18) plasma oestradiol concentration was above the detection limit of the assay, i.e., < 7 pmol/l, in all ROT-bitches but below the detection limit in all ovariectomised bitches. Basal plasma LH concentration was significantly higher in ROT-bitches (4.1 ± 0.7 μg/L) than those in anoestrus (0.64 ± 0.04 μg/L), and significantly lower than in ovariectomised bitches (20.2 ± 3.6 μg/L). Basal plasma LH concentration was relatively high in bitches in which there was a long interval between ovariectomy and appearance of oestrus. GnRH administration resulted in a significant increase in plasma LH and oestradiol concentrations in ROT-bitches. The GnRH-induced increase and subsequent decline in plasma LH concentration were significantly less in ROT-bitches than in either ovariectomised bitches or those in anoestrus. The GnRH-induced increase in plasma oestradiol concentration was significantly smaller in ROT-bitches than in those in anoestrus. In conclusion, the results of this study demonstrate that in dogs ROT is associated with noticeable changes in the pituitary-ovarian axis and suggest that a GnRH stimulation test may be used to distinguish between completely ovariectomised bitches and those with ROT.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. J.J.C.W.M.Buijtels@uu.nl
authors.forename: J J C W M
authors.initials: JJ
authors.lastname: Buijtels
authors.forename: J
authors.initials: J
authors.lastname: de Gier
authors.forename: H S
authors.initials: HS
authors.lastname: Kooistra
authors.forename: E C
authors.initials: EC
authors.lastname: Naan
authors.forename: C H Y
authors.initials: CH
authors.lastname: Oei
authors.forename: A C
authors.initials: AC
authors.lastname: Okkens
mesh_terms: D000818:Animals; D004285:Dogs / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D030762:Estrous Cycle / Q000097:blood; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood; D010052:Ovariectomy / Q000662:veterinary; D010053:Ovary / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D010902:Pituitary Gland / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D014463:Ultrasonography
chemical_list: D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone