Successfully breeding your bitch is more than prenatal care, vet visits, and the joy of playing with puppies. It’s also a matter of exact timing. While a bitch’s heat cycle can last about a month, her most fertile period only lasts a few days. By breeding her within that window, you maximize the chances of conception. But by missing that window, even by just a few days in some instances, you risk having to wait until the bitch’s next heat cycle to try again, which can prove time-consuming and financially taxing.
Understanding the nuances of your dog’s heat cycle (particularly when she experiences ovulation) optimizes the likelihood of conception and helps you predict a whelping date. It also empowers you to make decisions about your bitch’s health, diet, and overall well-being. If you have specific questions regarding your dog’s needs, consult her veterinarian.
What to Know About the Heat Cycle
Female dogs reach sexual maturity at about 6 months, with the time of their first heat depending on their size and breed. Some dogs go into heat at 4 months, while others may not experience a heat until 6 months.
“Going into heat” refers to a period when an un-spayed female dog is receptive to mating and could become pregnant. Most bitches experience heat twice a year (with the exception of Basenjis that experience it once) for two to three weeks. Dr. Gavin Casper, DVM, Medical Director of Hometown Animal Hospital in Weston, FL, shares some more key information.
He says, “Dogs have four stages of their heat cycle, and two of them (proestrus and estrus) comprise what is commonly referred to as going into heat. This is where the dog has bloody discharge and vulvar swelling and receptivity towards a male. During this time, a female dog will go through ovulation.”
Ovulation refers to a short period during a dog’s heat cycle when her ovaries release egg cells that can be fertilized. It’s key to breed a female dog around the time of or during ovulation to increase the chances of successful impregnation.
Understanding the Hormones Involved in Ovulation
The three hormones that play the most critical roles in a dog’s heat cycle (and by extension, ovulation) include:
- Estrogen. At the start of a dog’s heat cycle, her body will release estrogen, which thickens the vagina and primes red blood cells. The release of estrogen could last between one and 21 days — sometimes longer.
- Luteinizing hormone (LH). After the estrogen cycle, an increase in LH will trigger ovulation, called “Day 0.” After 48 hours, the bitch will start ovulating, with her most fertile period being Day 4 through Day 6 after the initial LH spike.
- Progesterone. But how can breeders pinpoint when their dog experiences fluctuations in LH levels? By testing her progesterone levels, which correspond with the increase in LH. This can be accomplished through a blood test or vaginoscopy, a diagnostic examination that assesses the dog’s reproductive system. Progesterone testing is key because it helps breeders pinpoint the day a bitch will whelp, which is especially helpfully if a planned C-section is involved.
Testing allows for the exact timing of ovulation in breeding bitches. Yet, some behavioral changes may also indicate the onset of this period. Dr. Casper’s family breeds Nova Scotia Duck Tolling Retrievers, and from experience, he describes:
“When the females ovulate, they exhibit a similar grouping of behaviors – ‘flagging’ or standing in front of males enticing them to be mounted or mounting other dogs, urinating frequently when outside, sometimes nesting behaviors, and some whining and restlessness.”
Timing Ovulation in Your Breeding Bitch
Dr. Scarlette Gotwals, DVM, has more than 20 years of experience researching and working in the canine reproductive field. During her appearance on the AKC Canine Health Foundation’s podcast, she emphasized the importance of accurately testing dogs’ progesterone to predict LH surges and increase bitches’ fertility.
Dr. Gotwals shares: “Progesterone is baseline prior to the LH surge, begins to rise at the time of the LH surge, is in the 4-8 nanograms-per-milliliter range by time the bitch ovulates, and is greater than 20 nanograms per milliliter (often 30-40 ng/mL) range by the time the bitch is in her peak fertile period.”
In other words, before a bitch experiences an LH spike, her progesterone levels will be baseline, with their exact values depending on what’s “normal” for your dog. A dog’s basal progesterone level is less than 1ng/mL; progesterone will measure 4-8 nanograms-per-milliliter range by the time the bitch ovulates. At her peak fertile period, the bitch’s progesterone levels will be in the 30-40 ng/mL range.
“The most common error with ovulation timing is to stop [progesterone] testing too soon,” Dr. Gotwals continues. “Sometimes breeders are so excited their bitch has come into season that they start checking progesterone levels too early and too frequently … They also may perceive a subtle fluctuation in baseline as ‘she’s going up’ and don’t confirm the sustained rise with a significantly elevated value. In these cases, they end up breeding too early, and the bitch misses.”
Dr. Gotwals notes that breeders can prevent this by understanding their bitch’s baseline progesterone levels, then test around the time of the LH spike and continue to test until they confirm ovulation with 4-to-8 nanograms per milliliter or greater.
Timing Whelping in Your Pregnant Bitch
If your bitch is successfully impregnated, she should deliver puppies more or less 65 days from the date of the LH surge or 63 days from ovulation, not the time of the breeding itself. That’s because healthy sperm can survive inside the female for three to seven days, and it can impregnate the female once she ovulates. So, if a bitch breeds with a stud, she might not become pregnant until days after when her LH surges, and her body releases egg cells.
Continuing to measure a pregnant dog’s progesterone levels is a great resource when predicting whelping or planning elective c-sections (which is fairly common in some breeds). At the time of delivery, the bitch’s progesterone levels will usually be less than 2.0 nanograms per milliliter.
Tips for Successfully Breeding Your Bitch
Pinpointing your bitch’s most fertile period is just one aspect of successfully breeding her. There are also other aspects to consider, such as the quality of the stud’s semen. As noted, robust sperm can last three to seven days after being deposited into a female. However, low sperm count, abnormal sperm, or poor motility could complicate conception and allow less room for error when timing ovulation.
“When using frozen semen or semen of poor quality, blood samples [from the bitch] should be drawn daily and tested for LH,” Dr. Gotwals expands. “Typically, progesterone levels are run every other day and serum saved from the days in between. Once the progesterone rise is documented, the appropriately saved samples can be tested for LH. Progesterone levels need to be followed until ovulation is clearly confirmed.”
Dr. Casper says that beyond understanding your bitch’s heat cycle and checking her progesterone levels, you should also take extra steps to ensure her health and well-being. He says, “While a dog is ovulating, breeders should monitor for any troubling signs of underlying illness, such as abnormal colored or foul-smelling vaginal discharge, signs of a uterine infection like lethargy, vomiting, diarrhea, fever, or pain, or drastic behavioral changes, like aggression or severe restlessness. Any of these signs warrant veterinary intervention.”