after a single injection of alhs ( 10 ml , i.m . ) at day 42 of pregnancy ( n = 2 ) or the ovarian cycle ( n = 3 ) , progesterone was reduced ( p less than 0.05 ) to 7-24 % of preinjection values within 1-2 days , and by 4-8 days returned to levels not different from those in control bitches treated with normal horse serum .
C0032961
pregnancy
C0033308
progesterone