How can we find out ovulation has occurred?
The timing for ovulation can be conducted using vaginal cytologic exams. Or it can be either conducted by assessing the concentration of progesterone in serum or testing for LH. To review the full cycle before breeding, tests are usually conducted on the first few days of proestrus phase and can be performed up to every 2-3 days to get the best time for breeding.
Progesterone concentrations are usually obtained every 48 hours when about 70% of the epithelial cells are cornified. The aim is to detect the first day when progesterone rose, which also correlates with the surge in LH. This day is known as day zero, and is used to determine the day that the bitch is most fertile. Usually, 2-7 days after day zero mark the days when the bitch is most fertile for breeding and to produce better rates of conception. However, the specific days and number of breeding depend on the type of semen being used. This could be fresh semen, chilled, or frozen.
When LH testing is used to determine the timing for ovulation, serum samples are tested daily. The samples are collected when the vaginal cytology contains a minimum of 70% superficial cells. An additional progesterone test is conducted 48 hours later to confirm LH surge or the initial increment in progesterone.