The visible signs of a bitch "spotting" as she comes in to season will only give an approximate indication of ovulation time , which can vary considerably between breeds and individuals. For breeding purposes, often travelling considerable distances to a suitable stud dog, taking the guesswork out of ovulation can save a lot of time , effort and possible disappointment if you miss the boat. This can be detected accurately by assessing the initial rise in Progesterone levels. Sampling is generally taken on an alternate day basis until a rise in hormone level is detected.
Our laboratory provides a semi-quantitative ELISA test to measure the progesterone levels in a sample of blood. At the end of Pro-oestrus, the maturing follicle will secrete less oestrogen, which triggers a luteinising hormone(LH) surge. This in turn will trigger a rise in progesterone from 2-4 ng/ml up to 10 ng/ml. This is the threshold level to stimulate ovulation. Hence we can forecast the optimal time for mating.
A similar test can be used for mares, especially those who may be slow to start cycling at the beginning of the season, when monitoring of the Progesterone levels enables the vet to determine when the mare is likely to be susceptible to treatment. This can also be a useful test with mares undergoing AI treatment, especially those who do not obviously "show". For further details, please refer to our stud section.