Narrowing down your dog’s whelping date

by Dr. Mikel Delgado, PhD

In order to know when to expect puppies, you’ve got to know when your bitch is ovulating (releasing eggs from her ovaries). You might think that whelping would be based on the mating date, but it’s not; it’s actually based on your bitch’s ovulation date!

How do we know when she’s ovulating?

Ovulation happens during estrus, the second stage of the reproductive cycle. There are several hormones and physical changes that can pinpoint the most likely time that your bitch is ovulating. 

Progesterone testing: to measure ovulation

Progesterone is a hormone released by the corpus luteum (in the ovaries). It leads to physical changes that support conception and pregnancy. Progesterone increases significantly around the time of ovulation, and measuring progesterone levels can help you determine the optimal time to breed your bitch.

A series of blood tests can measure the levels of progesterone in the blood. Progesterone testing should be started soon after signs of proestrus are observed (usually starting on day 6 of the heat cycle), and then repeated every two to three days until levels approach 3.0 ng/ml. A test the next day can confirm ovulation, which occurs at 5.0 ng/ml. A follow up test can confirm that ovulation actually occurred, as progesterone levels increase to around 20-30 ng/ml post-ovulation.

The optimum time to breed is 2-3 days after ovulation. Whelping generally occurs 63 days after ovulation.

Luteinizing Hormone testing: to measure the LH surge

Luteinizing Hormone is released by the pituitary gland to stimulate the production of estrogen, ultimately causing ovulation to occur. Bitches ovulate approximately 48 hours after the LH surge.

LH testing is often done in conjunction with progesterone testing, starting during the proestrus stage. Frequent sampling (even daily blood testing) is ideal as the surge only lasts 12-24 hours. LH levels rise, followed by an increase in progesterone levels, which confirms the LH surge.

It is recommended that a bitch is bred 4-7 days after the LH surge. Whelping usually occurs 65 days after the LH surge.

Vaginal Cytology: to measure changes in the estrus cycle

Swabs of the surface of the vaginal walls can be assessed under a microscope to determine the phase of the reproductive cycle. As estrogen increases, the number of “cornified” cells also increases. These cells look larger and flatter, with a small or absent nucleus. 

During estrus, there will be a large percent of cornified cells; 7-10 days after the LH surge, the cells will change dramatically to immature cells. Whelping will generally occur 56 to 58 days after this change, assuming that mating happened.  

Vaginal swabs should be taken frequently to assess cell changes. Cytology can detect changes in the estrus cycle, but it is not optimal for determining peak fertility, the LH surge, or ovulation. 

Vaginoscopy

Vaginoscopy allows a veterinarian to closely examine the inner lining of the vaginal walls (the mucosa) to assess changes related to the different stages of the reproductive cycle. Swelling and color changes in the vaginal walls occur during proestrus. During estrus, the swelling is reduced and the walls of the vagina have prominent, wrinkled folds. 

Vaginoscopy requires specialized equipment such as a proctoscope or otoscope. 

When is she fertile?

The optimal breeding date is 2-3 days after ovulation, but dogs are generally fertile from 3 days before ovulation until 4 days after ovulation.

When will she whelp?

Dogs whelp 63 days after ovulation, and 65 days after the LH surge, give or take a day.

The more accurately you time the LH surge and/or ovulation, the more accurately you can prepare for the whelping date. If your dog is 68 days past breeding, consult with your veterinarian ASAP as delayed whelping can be associated with dystocia and neonatal mortality.

Why is timing so important?

Paying attention to the timing of ovulation gives you the best chance of a successful pregnancy with each mating or insemination. Breeding during your dog’s most fertile window may also increase her litter size. Knowing the whelping date can also help with planning cesarean sections, and can also help you know when you have a potential emergency on your hands. 

Careful attention to timing may require some extra work, but is an incredibly worthwhile practice that will benefit your breeding program and your breeding dogs!

References and resources

VIN: Breeding Management and Ovulation Timing in the Bitch

Reproductive Revolutions: Ovulation Timing in the Bitch

DVM360: Breeding management 102 - It's all in the timing

DVM360: Canine breeding management--vaginoscopy and progesterone assays

Greer, M. L. (2014). Canine reproduction and neonatology. CRC Press.

Karabulut, T. S. F. T. Determining the optimal time of mating in bitches. Journal of Istanbul Veterinary Sciences, 1-1.

Kutzler, M. A., Mohammed, H. O., Lamb, S. V., & Meyers-Wallen, V. N. (2003). Accuracy of canine parturition date prediction from the initial rise in preovulatory progesterone concentration. Theriogenology, 60(6), 1187-1196.

Lopate, C. (2008). Estimation of gestational age and assessment of canine fetal maturation using radiology and ultrasonography: a review. Theriogenology, 70(3), 397-402.