Correlation of serum progesterone levels with reproductive events and actions.
Progesterone levels
(Can vary)
Approximate day of heat cycle.
(Can vary greatly)
Event
Action
<1.0 1 - 6 Proestrus do a baseline progesterone level
1.0 - 1.9 6 - 9 Ovulation minus approximately 3 days check progesterone levels and do smears every other day. Do LH peak if using frozen semen or semen of less than optimal quality.
2.0 - 2.9 (LH peak) Early Estrus
Ovulation should occur in 2-3 days. 
Continue to follow smears and progesterone levels until level of 4.0 - 5.0 is reached. This will help insure that ovulation has occurred.
4.0 - 5.0 10 Mid estrus Ovulation occurs Eggs need 2 more days to mature  Breeding to start in 2 - 3 days
> 6.0 - 8.0 12 Eggs are mature

Continue to follow smears. No further progesterone levels are required.
Breeding begins:

  • Natural 2 - 3 days after a level of 4 - 5 is reached
  • A.I. 2 - 3 days after a level of 4 - 5 is reached
  • Surgical with frozen or compromised semen 3 days after a level of 4 - 5 is reached. 5 days after 2.0 - 3.0 is reached
- 16 - 19 Diestrus
Indicated by change in vaginal smears and/or failure of bitch to stand for male