Use of pulsatile intravenous administration of gonadotropin-releasing hormone to induce fertile estrus in bitches.
The pulsatile IV administration of gonadotropin-releasing hormone (GnRH) was evaluated as a method to induce fertile estrus in 8 anestrous Beagle bitches. Bitches received 1.25 micrograms of GnRH every 90 minutes for 11 to 13 days. Gonadotropin-releasing hormone was delivered by use of an automatic pump. Reproductive history was known for all bitches, 4 of which, on the basis of 3 or 4 preceding cycles, had an interestrous interval of 219 +/- 14 days (mean +/- SEM). Estrus induction was attempted during early anestrus in 6 bitches (ie, 148 +/- 10 days since the preceding estrus) and late anestrus in 1 bitch (ie, 260 days since the preceding estrus); another bitch had not had an estrous cycle for nearly 2 years before GnRH administration. Signs of estrus were seen within 16 days after the start of GnRH administration in the bitches with regular estrous cycles (group 1, n = 7), and within 23 days in the bitch (group 2) with prolonged anestrus. All bitches were bred, and 7 of 8 (87.5%) became pregnant, with a mean litter size of 4.5 +/- 0.75. A normal hormonal response pattern was observed in group-1 bitches--a peak increase in plasma estrogen concentration of 22.3 +/- 2 pg/ml immediately before the onset of estrus. Peak plasma progesterone concentration (17.3 +/- 3 ng/ml) was observed 1 to 14 days after the onset of diestrus in the group-1 bitches that ovulated, and adequate plasma progesterone concentration was maintained throughout gestation.(ABSTRACT TRUNCATED AT 250 WORDS)
Cain
J L
JL
Department of Veterinary Medicine, University of California, Davis 95616.
Cain
G R
GR
Feldman
E C
EC
Lasley
B L
BL
Stabenfeldt
G H
GH
D000818:Animals; D004285:Dogs / Q000502:physiology*; D004967:Estrogens / Q000097:blood; D004973:Estrus Synchronization; D005260:Female; D005298:Fertility / Q000187:drug effects*; D007260:Infusion Pumps / Q000662:veterinary; D007262:Infusions, Intravenous / Q000662:veterinary; D010906:Pituitary Hormone-Releasing Hormones / Q000008:administration & dosage* / Q000494:pharmacology; D011247:Pregnancy; D011374:Progesterone / Q000097:blood
D004967:Estrogens; D010906:Pituitary Hormone-Releasing Hormones; D011374:Progesterone