Canine Artificial Insemination
Knowing exactly when to inseminate the female can be quite challenging and, if not done properly, fertilization will not occur. In traditional breeding programs, with natural service, the bitch is bred at least three times on the 9th, 11th and 13th day after the vulva begins to swell and blood tinged discharge is seen. On average, bitches tend to ovulate on the 12th day after the onset of vulvar swelling. Unfortunately, this does not always occur and alternative methods may be required for some bitches to conceive. The goal of breeding is to inseminate the bitch four days before ovulation and then every two days until the final insemination at two days after ovulation. Insemination two days after ovulation results in the maximum litter size.
Determination of ovulation can be done in a variety of ways. Traditionally, tissue cells of the vagina are microscopically evaluated. Based on the appearance of these cells, the time of ovulation can be estimated. Unfortunately, this is not the most accurate method of determining ovulation.
The measurement of progesterone levels is much more accurate but is time consuming and daily checks throughout the heat cycle is not always practical or affordable. The hormone progesterone can be measured within the blood. The most accurate measurements can effectively predict ovulation, but these tests are done in a laboratory. An in-hospital version of the progesterone level test is available, which can give the user a rough idea when ovulation is going to occur.
A combination of the two methods has a pretty good success rate. About 4 to 5 days after the beginning of vulvar swelling and blood tinged discharge, the cells of the vagina should be evaluated daily. Once 80 percent of these cells have the typical cornified appearance indicating ovulation is near, blood samples are drawn every 2 to 3 days to evaluate progesterone levels. At this point, if there is not a limit to the number of inseminations, the first insemination is performed. If only one insemination is possible, this one should be done 2 days after ovulation.
Further evaluation of the vaginal cells is no longer necessary. Every 2 to 3 days, blood samples should be evaluated for progesterone levels and insemination occurs. Once the progesterone levels reach ovulation level, one final insemination is done 2 days later. Pregnancy can then be confirmed about 25 days later with an ultrasound.
Progesterone levels can be determined either by a laboratory or by an in-hospital test kit. The laboratory can give specific values to the progesterone level. The in-hospital test kit can indicate levels of progesterone based on color changes.
For laboratory values, the serum progesterone is typically less than one ng/ml until 2 days before ovulation. At this time, the level of progesterone will rise to 1 to 2 ng/ml. On the following day (one day before ovulation), the progesterone level will be 2 to 4 ng/ml. On the day of ovulation, the progesterone will be 4 to 10 ng/ml. After ovulation, the progesterone levels rapidly rise and can be anywhere between 15 to 90 ng/ml.
For the in-hospital test, there are sample color changes that can help indicate approximately where in the ovulation process the dog is in currently.