The 63-Day Countdown

How to Count on the Countdown!

You might be confused about when your bitch is due or even how 63 days plays into it. Did you know puppies can be born as early as Day 58 or as late as Day 68? It depends entirely on when you are counting from, and how you arrived at Day 0 (plus or minus a few other factors). Let’s dive into the best way to predict when your bitch is going to whelp, including the significance of 63 days.

To understand how the countdown works, we need to establish a few details first. Day 0 in all published literature refers to the day of ovulation. This is NOT to be confused with the day of mating or insemination, or even when the bitch came into season. Puppies are typically due around Day 63 (averaging around 62 to 64 days) after the start of a female dog’s ovulation. An easy way to remember this is, instead of a 9 month gestation period like humans, dogs will deliver their puppies 9 weeks after ovulation. However, factors such as breed, size, and individual variations may also affect this time period.

Counting from Ovulation (62 – 64 Days)

In dogs, the most reliable way to detect ovulation is by performing vaginal cytology and measuring progesterone levels in the blood. Vaginal cytology involves taking a sample of cells from the vagina using a swab and examining them under a microscope. As a dog approaches ovulation, the cells in the vaginal lining change in appearance and structure, indicating the imminent release of eggs. Progesterone levels in the blood rise rapidly just before ovulation and remain elevated for several days. Measuring progesterone levels can help determine the optimal time for breeding or artificial insemination.

Additionally, changes in behaviour and physical signs such as a swollen vulva, increased urination, and a change in the consistency and colour of vaginal discharge may also indicate that a dog is ovulating. However, these signs are not as reliable as vaginal cytology and progesterone testing. But measuring with machines is not always perfect. It is worth noting that not all machines read progesterone levels 100% accurately, resulting in data being interpreted as slightly higher or lower than they actually are.  

Counting from Mating (56 – 68 Days)

Trying to estimate the due date from the date of mating can be tricky, and not very reliable in terms of giving an accurate due date. However, if you have had a natural mating and the female was receptive, it might help narrow it down. 

A receptive female is in what we refer to as “standing heat”. This is the period where she will actively entice and encourage mating. This window typically occurs from Day 2 to 6 following ovulation, but can also start earlier. If you have had more than one natural mating, and sighted them all, you have a better picture of the “standing heat” window. If matings occurred naturally over several days, you might know the first and the last day. Providing the window was about, or at least, 4 days long, the last mating would likely be on or around Day 6 from ovulation. If you are counting from a single mating with a receptive bitch, your female is likely in the region of Day 2 to 6, but there are no guarantees. 

It is important to note that many females become receptive to the male early, and will mate BEFORE ovulation. Semen has the ability to stay viable inside the female for up to 7 days (sometimes longer). Therefore, if the mating occurs before the eggs are even released, it may still be very possible for the sperm to be present and viable enough to fertilise the eggs once they mature some days later.

Final Thoughts

So, no matter how you count or what you do, it all comes down to ovulation. Try using our free chart, “63 Day Perpetual Breeding & Whelping Calendar“, to predict when your litter is due. As there are so many variances between individual dogs, breeds, and certain bitch bloodlines, we always recommend monitoring rectal temperature during the last week of pregnancy. Recording temperature trends during this period will help alert you to the timing of whelping through the pre-whelp temperature drop. You can access the free chart “Whelping Temperature Chart” here.