Find a dog's due date and whelping window from the breeding date, the LH surge, ovulation or diestrus, with the days for ultrasound, relaxin and the X-ray litter count.
Dog Pregnancy Calculator - Due Date and Whelping Window
Find a dog's due date and whelping window from the breeding date, the LH surge, ovulation or diestrus, with the days for ultrasound, relaxin and the X-ray litter count.
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Dog due date from a breeding, an LH test or ovulation
Pick what your date stands for, enter it, and the dog pregnancy calculator gives the due date, the normal whelping window, the day and week of pregnancy, and the dates for palpation, the relaxin test, ultrasound and the X-ray that counts puppies. The windows come from the Merck Veterinary Manual: 58 to 72 days after the first breeding, 64 to 66 days after the LH surge, 56 to 58 days after the first day of diestrus.
What to type, and where the date comes from
- What the date is - the first day the female accepted the male, the LH surge (or the first progesterone result above about 2 ng/mL), the estimated ovulation, or the first day of diestrus from vaginal cytology. Your veterinarian's breeding report names the one you have.
- The date itself - for two or three matings, enter the first one. The window already allows for sperm that wait several days in the tract.
- Count days as of - optional. Empty means today. Fill it in to see what the countdown will look like on a vet visit or on the day you leave for work.
Problem: a mating date leaves a fifteen-day guess
Most charts online add 63 days to the breeding date and print one day. Merck is blunt that breeding and conception dates "do not correlate closely enough to permit accurate prediction of whelping dates". Fresh semen can live in the vagina for 9 days or more, and the eggs are released 2 to 3 days after the LH peak and mature for another 2 to 3. A female bred early in her heat can conceive days after the mating. The honest answer from a breeding date is a range of 15 days, day 58 to day 72.
That matters on two dates: the night you start watching her, and the day a planned cesarean would be scheduled. Against the 58 to 72-day range, a single printed day 63 can be 5 days late or 9 days early.
Solution: date the pregnancy from a hormone, not the calendar
Serial progesterone or LH tests during the heat pin down the surge, and from there whelping comes 64 to 66 days later: a 3-day window instead of 15. The first day of diestrus, read from vaginal smears, works almost as well at 56 to 58 days. The calculator switches its window, its due date and its schedule of checks to whichever date you give it.
The table below dates one pregnancy four ways. The LH surge falls on March 1, ovulation two days later, and diestrus starts eight days after the surge. Every row lands on the same due date, and only the width of the window changes.
| Date you have | Days to whelping | Due date | Window |
|---|---|---|---|
| First breeding, March 1 | 58-72 (middle 65) | May 5 | April 28 to May 12, 15 days |
| LH surge, March 1 | 64-66 | May 5 | May 4 to May 6, 3 days |
| Ovulation, March 3 | 61-64 (likely 63) | May 5 | May 3 to May 6, 4 days |
| First day of diestrus, March 9 | 56-58 | May 5 | May 4 to May 6, 3 days |
The ovulation row is derived, not quoted: Merck gives 64 to 66 days from the LH peak and ovulation 2 to 3 days after it, which leaves day 61 to 64. The breeding row's due date is simply the middle of the range, and on a real dog it is the least reliable number on this page.
Which check answers which question, and on what day
Each test works only inside its own stretch of the pregnancy. The day counts below are from the LH surge; the dates are for a surge on March 1. With a breeding date the calculator counts from the mating instead and says so under the result, because those dates can be a few days off.
| You want to know | Check | Gestation day | Surge on March 1 |
|---|---|---|---|
| Is she pregnant at all? | Palpation by a vet | from about 21, harder after 35-38 | March 22 to April 5 |
| Pregnant, by a blood test? | Relaxin blood test | after 22-27 | from March 28 |
| Are the puppies alive? | Ultrasound | best 25-35, can miss before 21 | March 26 to April 5 |
| Are bones forming? | X-ray | visible from about 42-45 | from April 15 |
| How many puppies? | X-ray | after 55 | from April 26 |
| When is surgery safe? | Elective cesarean | after 62 | from May 3 |
The X-ray on day 45 and the one after day 55 are not the same visit. The early film shows that skeletons are there; only the late one is the litter count you want before whelping, so you know when the last puppy is out.
Signs that the window has opened
Merck lists a drop in rectal temperature to 98.1-100 °F (36.7-37.8 °C), with a mean of 98.8 °F, in most dogs 8 to 24 hours before whelping, as progesterone falls. Labor usually starts within 24 hours of progesterone dropping below 2 ng/mL. A relaxed perineum and full mammary glands also show up, but Merck calls them neither sensitive nor specific, so they do not date anything on their own.
Past the last day of the window the calculator turns its status red and says to call the veterinarian. It does not try to guess how long waiting is safe.
Dog pregnancy questions with dates attached
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