Abstract
Induction of abortion in cows with Prostaglandin F2α-analogue or with Dexamethasone.
Yohji Ohnami, M. Sasaki, M. Kikuchi (School of Vet. Med. Anim. Sci., Kitasato Univ.)
When plostaglandinF2α-analogue (PGF2α-A) was administered at a dose of 0.8-2.4mg into 29 cows in the 2nd-8th month of pregnancy, an abortion was induced in all of the 16 cows in the 2nd to the 4th month of pregnancy, 5 of the 6 in the 5th month, but not in the cows in the 6-8th month. When administered with dexamethasone (Dx) at 30mg, an abortion was induced in neither of the two cows that were less than 5 months pregnant. However, abortions were induced in 2 of the 3 in the 5th month, one in the 6th month, and both in the 8-9th month of pregnancy experienced an abortion or went into premature labor.
Retained placenta was not found in the cows up to the 4th month of pregnancy, but it was observed in all of the cows that were pregnant more than 5 months. In respect to the occurrence of retaind placenta, there was no difference between PGF2α-A and Dx administration. The mean blood progesterone (P) level in the cows which underwent an abortion were 0.9 ng/ml or less at the time around the abortion, although the level was 5.7 ng/ml on the day of PGF2α-A administration. The P level of the cows in which an abortion was induced by Dx, was 6.8 ng/ml on the day of drug administration and reached 1.0 ng/ml or less more than 3 days later. These results indicate that PGF2α-A is markedly effective in inducing an abortion in cows up to the 4th month of pregnancy and Dx is effective in cows pregnant 6 months or more.
