Induction of fertile estrus in bitches using a sustained-release formulation of a GnRH agonist (leuprolide acetate).
A single subcutaneous injection of a sustained-release formulation of a potent GnRH agonist, leuprolide acetate (LA; [D-Leu6, Pro9NEt]-GnRH), was evaluated as a method of inducing fertile estrus in 12 mature anestrous and 6 prepubertal beagle bitches. The bitches were treated with microencapsulated LA (100 micrograms/kg, s.c.) at 120 or 150 d post partum, or at 1 yr of age, followed by a GnRH-analogue (fertirelin; [Pro9NEt]-GnRH, 3 micrograms/kg, i.m.) on the first day of induced estrus. Signs of estrus were seen within 10.3 +/- 0.9 d after LA administration in all bitches. The interestrous interval in 120- and 150-d post-partum bitches was shortened (P < 0.05) to 191 +/- 3 and 222 +/- 3 d, respectively, compared with 264 +/- 11 d in control bitches. All LA treated dogs demonstrated behavioral estrus and mated. Three of 6 (50%) at 120 d post partum, 6 of 6 (100%) at 150 d post partum and 5 of 6 (83%) of prepubertal (1-yr old) bitches then became pregnant and produced a mean litter size of 4.1 +/- 0.8 pups. A normal circulating estrogen and progesterone response pattern was observed in mature anestrous bitches. A prepubertal bitch that failed to become pregnant had a similar estrogen response pattern but an insufficient progesterone profile. The results suggest that microencapsulated LA can be useful in inducing fertile estrus in the domestic dogs.
Inaba
T
T
Department of Animal Reproduction, College of Agriculture, Osaka Prefecture University, Sakai, Japan.
Tani
H
H
Gonda
M
M
Nakagawa
A
A
Ohmura
M
M
Mori
J
J
Torii
R
R
Tamada
H
H
Sawada
T
T
D000780:Anestrus; D000818:Animals; D002214:Capsules; D003692:Delayed-Action Preparations; D004285:Dogs; D004967:Estrogens / Q000097:blood; D004971:Estrus / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005298:Fertility; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D006728:Hormones / Q000008:administration & dosage / Q000494:pharmacology; D016729:Leuprolide / Q000008:administration & dosage / Q000494:pharmacology*; D008098:Litter Size / Q000187:drug effects / Q000502:physiology; D049590:Postpartum Period; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012741:Sexual Maturation; D013997:Time Factors
D002214:Capsules; D003692:Delayed-Action Preparations; D004967:Estrogens; D006728:Hormones; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D016729:Leuprolide; C009936:fertirelin