SERUM PROGESTERONE PROFILE DURING DIFFERENT STAGES . OF INDUCED AND NATURAL ESTROUS CYCLES IN BITCHES

Abstract

Estrus was induced in twelve anestrus bitches using a sustained release preparation of leuprolide acetate
and diethylstilbestrol. Bitches with GnRH regimen of estrus induction (n=6) showed a mean serum progesterone
level of 0. 72 ± 0.33 ng/ml on the first day of treatment, 0.28 :t: 0.08 ng/ml on the second day of proestrus, 3.80 ±
1. 07 ng/ml on the first day of estrus, 15.12 ± 3. 73 ng/ml on the day of second mating and 17. 92 ± 1.15 ng/ml on
the tenth day of second mating. Bitches treated with diethylstilbestrol (n=6) showed a mean serum prog9Sterone
profile of0.47 ± 0.27 ng/ml on the first day of treatment, 0.2 ng/ml on the second day of proestrus, 5.53 ± 0.66 ng/
ml on the first day of estrus, 13.67 ± 2.84 ng/ml on the day of second mating and 15.87 ± 0.27 ng/m1 on the tenth
day of second mating. Animals in natural estrum (n=6) showed a mean serum progesterone level of 0.36 ± 0.12 ng/
ml on the second day of proestrus, 3.56 ± 0.50 ng/ml on the first day of estrus, 8.12 ± 0.36 ng/ml on the day of
second mating and 17.80 ± 0.58 ng/ml on the tenth day of second mating. In treatment groups, the serum
progesterone levels raised quickly to higher levels during estrum when compared to control animals, but in all
animals it reached to similar levels by metestrum. Retrospective studies revealed that ovulation occurred in GnRH
treated and diethylstilbestrol treated animals by 8th to 11 111 day and 6th to 1111> day from first day of proestrus
respectively. Ovulation occurred in estrus induced animals earlier than that in control animals which is due to the
shortened and pronounced proestral changes in treated animals. But in animals where estrus was induced using
diethylstilbestrol, the ovulatory period was inconsistent which necessitates more frequent assessment of
progesterone profile for timing of ovul_ation.1 GnRH treated animals, diethylstilbestrol treated animals and control
animals had a conception rate of 83. 3, 50 and 83.3% respectively with similar gestation length and litter size in all
groups. It is concluded that serum progesterone profile studies can be employed for selecting good subjects for
estrus induction treatment, timing of ovulation and to assess the normal progression of the estrous cycle in natural
and induced estrous cycles.