Signs of labor in dogs: the temperature drop and the red flags

Call your vet now if

1. Hard straining, no puppy: visible abdominal pushing for 1–2 hours without a puppy being born.
2. Stage 1 that doesn’t progress: restless, nesting behavior for more than 24 hours with no straining.
3. A long delivery: the delivery isn’t finished 4–9 hours after hard straining began.
4. Green discharge. Merck lists green discharge as abnormal.
5. A puppy born dead or very weak, or the mother seems in severe distress.
6. No labor at term: she reaches the end of her due-date window, or day 68 after the LH surge, with no signs of labor.

Have ready: when her temperature dropped, when stage 1 started, when hard straining started, how many puppies and afterbirths you’ve seen, and the color of any discharge.

The temperature drop: the sign you can measure

Merck reports that most dogs show a drop in rectal temperature to an average of about 98.8 °F (37.1 °C), within a range of 98.1–100 °F (36.7–37.8 °C), 8 to 24 hours before whelping. It happens because progesterone falls at the end of pregnancy; most dogs start stage 1 labor within 24 hours of progesterone dropping below 2 ng/mL.

To catch it, take her rectal temperature 2 or 3 times a day, starting 1 week before the predicted due date, and write down each reading with the time, as Concannon’s review describes. A drop stands out against her own earlier readings.

Don’t rely on temperature alone. A 2021 review of ways to predict whelping reports that, in a study of vaginal temperature, a drop flagged labor within the next 48 hours in only about 7 of 10 dogs, and it advises against using rectal temperature on its own to predict the day. If she shows the signs of labor below, labor counts even without a recorded drop.

Example: for a dog whose most likely due date is Saturday, October 3, 2026, temperature checks start on Saturday, September 26, 2026. If she was bred on August 1, her published window runs to Monday, October 12, 2026; past that date without labor is a reason to call.

Stage 1: the quiet part (usually 12–24 hours)

Stage 1 normally lasts 12–24 hours. The cervix opens and the uterus contracts, but you won’t see her push. What you may see instead:

• restlessness, hiding and nesting, often on and off;
• refusing food, and sometimes vomiting;
• panting and trembling;
• a clear, watery discharge.

Concannon’s timeline has nesting and restlessness beginning over the last 2–4 days of pregnancy, as progesterone starts to fall. Stage 1 that runs past 24 hours with no straining is one of the call-now points above.

Stage 2 and stage 3: puppies and afterbirths

Stage 2 starts with visible straining — her belly tightens and she pushes — and each bout should end in a puppy. Merck’s chapter says straining usually shouldn’t last more than 1–2 hours between puppies, although it varies a great deal. In normal labor, puppies arrive every 30–60 minutes, and the whole delivery is ideally done in about 7–9 hours.

Stage 3 is the delivery of the afterbirth (placenta). Dogs move back and forth between stages 2 and 3, and an afterbirth doesn’t always come out right after its puppy. Between deliveries she may rest, nest, lick and nurse the puppies already born; panting and trembling are common.

Discharge during delivery can be clear, watery or bloody. Merck lists green discharge as abnormal, so call if you see it.

Afterbirths can be eaten by the mother, pass without being noticed, or come out within 24 hours, and Merck says she doesn’t need to eat them. Counting them still helps your vet, so note any you see.

Don’t give her any medicine or supplement to speed things up unless your vet tells you to. Merck’s chapter describes labor drugs as something vets use only after monitoring the strength and pattern of the contractions, because given too early they work poorly.

After the last puppy

Merck advises confirming that every puppy has been born with an ultrasound, an X-ray or, less reliably, a hands-on exam, so ask your vet whether she should be checked. After whelping, a heavy, dark red to black, odorless discharge for the first few days is normal. Keep track of her temperature, the discharge and her milk, and tell your vet about any change.

Weigh each puppy once it’s dry, then twice a day for the first week. Merck advises immediate attention for any puppy that loses weight, or fails to gain about 10% of its body weight a day, after the first 24 hours.

Cats are different

Queens give no reliable temperature warning. A feline textbook chapter notes that a drop of about 1 °F can come before labor but that the sign can be unreliable, so our pregnancy calculator shows no temperature countdown for cats. In a survey of births in 197 queens, the median gap between kittens was 30 minutes and 95% of kittens arrived within 100 minutes of the one before, so a gap longer than 100 minutes is a reason to call. Strong straining for 1–2 hours without a kitten also calls for your vet, and kittens born before day 60 after mating tend to be less viable.

Next step

Put her breeding dates — or the LH surge or ovulation date from your vet — into our dog pregnancy calculator to get the due-date window, the day to start temperature checks and a calendar file. Our dog pregnancy timeline covers the weeks before labor.