Suppression of the oestrous responses of bitches to the GnRH analogue deslorelin by progestin.
Studies were undertaken in Australia and Belgium to determine whether the initial pro-oestrous-oestrous responses of anoestrous bitches to treatment with deslorelin administered in a s.c. implant were inhibited by progestin treatment. Thirty-nine bitches of mixed breeding were treated daily with 2 mg megestrol acetate kg-1 body weight for 21 (group 1, n = 5) or 14 days (group 2, n = 10), or with 1 mg megestrol acetate kg-1 body weight for 14 days (group 3, n = 10). A deslorelin (6 mg) implant was placed s.c. on day 14 (group 1) or day 7 (groups 2 and 3) of treatment. Bitches not treated with progestin also received a deslorelin implant (group 4, n = 9) or were untreated controls (group 5, n = 9). Signs of pro-oestrus-oestrus were not observed in bitches in groups 1, 2 and 5, but were observed in bitches in groups 3 (4/10) and 4 (9/9). Four bitches in group 4 were mated, two of which became pregnant. The pregnancies failed at about day 40 of gestation and were associated with low plasma progesterone concentrations. Treatment with progestin inhibited the pro-oestrous-oestrous responses of bitches to deslorelin.
Wright
P J
PJ
Department of Veterinary Science, University of Melbourne, 250 Princes Highway, Werribee 3030, Victoria, Australia.
Verstegen
J P
JP
Onclin
K
K
Jöchle
W
W
Armour
A F
AF
Martin
G B
GB
Trigg
T E
TE
D000818:Animals; D003270:Contraceptive Agents / Q000008:administration & dosage*; D003864:Depression, Chemical; D004285:Dogs; D004343:Drug Implants; D004958:Estradiol / Q000097:blood; D004971:Estrus / Q000187:drug effects*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D019290:Megestrol Acetate / Q000008:administration & dosage*; D011247:Pregnancy; D011374:Progesterone / Q000037:antagonists & inhibitors / Q000097:blood; D013997:Time Factors; D017329:Triptorelin Pamoate / Q000031:analogs & derivatives
D003270:Contraceptive Agents; D004343:Drug Implants; D017329:Triptorelin Pamoate; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D019290:Megestrol Acetate; C066438:deslorelin