AKC eNewsletter

Summer 2005

Ovulation: Timing is Everything

By Katherine Settle, DVM

As breeders, many of us have been successfully breeding dogs for a long time. For the most part, we breed when the bitch “says” she’s ready and the stud “says” she’s ready. Ovulation timing is important because 75 percent of the missed breedings can be contributed to improper timing of the breeding. Since some of us are now in a new age of long-distance breeding, where the bitch and stud stay at home and the semen travels, timing the bitch’s ovulation is critical.

Do your homework in hopes that your biggest worry will be the sleep that you lose on whelping night. Border Terriers.
Credit: Isabelle Francais.
By keeping accurate breeding history records, we can get an idea of future heat cycles. Always keep a record of the date, the day of the cycle the bitch was bred, the results of the 30-day pregnancy ultrasound or test results, the date of whelping, and the number of pups. Even if the bitch was not bred, you can get an idea if the cycle was long or very short and when she began flagging.

There are three ways to help us determine ovulation in a bitch. By doing vaginal smears on a bitch, we can get an idea of when she should be receptive. If we continue to do vaginal smears, we can determine the day that the smear makes a 20 percent change back from cornified (superficial and anuclear cells) to non-cornified (para-basal and intermediate superficial cells). This smear is called a diestrus smear. If we count back 6 days, that is the approximate day of ovulation. Another post ovulation way is to count back 63 days from whelping. As you can see, neither of these is helpful for the current breeding cycle. So the best way to time ovulation is with hormones. Progesterone is the hormone we use most often.

Some progesterone tests are run in the veterinary hospital and give a range of numbers, such as 3-10ng/ml. This may be adequate if you are doing multiple tests and plan a breeding with the male present. If we assume that male sperm can live around six days, you can afford more flexibility with the timing. However, with chilled semen we assume the cooled sperm can survive about three days, one in travel and two in the bitch. Frozen, we assume about 12-hour sperm survival, and the timing must be even more accurate. A radio immune assay progesterone (RIA) is the most accurate. RIA’s give you a result in a number, like 3.2ng/ml. Always check the laboratory turn-around time and the cost. Another test, LH, can also be done in the veterinary hospital, but I only use it to help support my progesterone result.

Keep accurate breeding history records to get an idea of future heat cycles.
I usually begin my progesterone testing around day 5 of a three-week cycle. Sometimes, I use the vaginal smear to tell me if progesterone testing would be too early. I repeat another progesterone depending on the previous progesterone result. The initial rise in progesterone represents the LH peak. Usually this is when the progesterone is around 2ng/ml. Two days later, I expect the progesterone to be within an ovulation range, which is around 3.5-5ng/ml. In a bitch (which is different from people and horses), the eggs are not ready to be fertilized when they are ovulated. They must go through another change, and are ready one to five days after ovulation. Using a bell curve and playing the averages, most bitches’ eggs are ready to be fertilized on day 3 after ovulation, less on days 2 and 4, and even less on days 1 and 5. So when breeding artificially, we put chilled semen in on day 2 after ovulation, thus the sperm cover day 2 and 3. For frozen we inseminate on day 3. Also, with frozen, semen should always be put into the uterus using surgical insemination or insemination by rigid endoscopy (TCI, Trans Cervical Insemination). In your planning stages for the desired breeding, be sure to check with the people on both ends about their availability to collect the male or inseminate the bitch. Can they be available on a Sunday? Also, remember that overnight deliverers currently do not pickup on Saturday or Sunday. If airlines are to be used, the person shipping must be a known shipper (Check with airlines for registration requirements). Sometimes, we must just work around these problems, which means we may have to settle for a day before or after we would have preferred.

In using these tests, we are basing our interpretation on averages. Also, not all bitches “read the book,” and many will have test results that do not follow what we expect. With these bitches, we evaluate all the tests and clues and use our best educated guess.

Do your homework and plan properly in hopes that your biggest worry will be how much sleep you lose on whelping night!

Dr. Katherine Settle, along with her veterinarian husband, John Schontz, own two veterinary practices. Settle has been working in canine reproduction for more than 24 years.

Article may not be reprinted without permission.

  Ronald N. Rella, director, Breeder Services
Theresa Shea, editor | Email: AKCbreeder@akc.org | Joanne Beacon, designer
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© The American Kennel Club 2005