Newborn puppies need a whelping box temperature of 85 to 90°F (29 to 32°C) during their first week of life. Unlike adult dogs, puppies cannot regulate their own body temperature at birth, so the environment you create for them is critical to their survival. Over the first four weeks, you can gradually reduce the temperature as they develop the ability to generate and retain their own heat.
Temperature Schedule: Week by Week
The temperature inside the whelping box should be warmest during the first week and then step down gradually. Here’s what to aim for:
- Week 1: 85–90°F (29–32°C) inside the whelping box, with the room itself at 75–80°F
- Weeks 2–3: 79–84°F (26–29°C)
- Week 4: 73.5–79°F (23–26°C)
By the time puppies are weaned, their internal body temperature has caught up to an adult dog’s, and they no longer need supplemental heat under normal indoor conditions.
Why Puppies Can’t Stay Warm on Their Own
Newborn puppies lack the shivering reflex. In adult dogs, shivering generates body heat quickly, but this mechanism simply isn’t developed at birth. Puppies also can’t constrict their blood vessels to conserve heat the way older dogs do. Their small body mass and thin coat mean they lose heat rapidly to the surrounding air.
A newborn puppy’s normal internal temperature reflects this vulnerability. During the first week, rectal temperature ranges from just 95 to 99°F (35 to 37.2°C), well below the adult dog’s typical 101 to 102.5°F. By weeks two and three, it climbs to 97 to 100°F. This gradual rise happens as their thermoregulation systems mature. One thing that is present from birth: panting. An overheated newborn can pant, even though a cold one cannot shiver.
What Happens When Puppies Get Too Cold
A drop in body temperature triggers a dangerous cascade. The puppy’s heart rate slows, and digestion in the stomach and intestines slows with it. Once a puppy becomes hypothermic, it loses its sucking reflex entirely. A puppy that can’t nurse takes in less energy, which makes it even less able to produce body heat, creating a spiral that can turn fatal quickly. If a chilled puppy needs to be fed, it must be warmed back to a normal temperature first, because milk given to a hypothermic puppy won’t be digested properly.
Cold also affects immunity. Hypothermic puppies are more susceptible to infection, and the mother may pay less attention to a cold, weakened puppy, compounding the problem.
How to Tell If Puppies Are Too Hot or Too Cold
Since you can’t ask a puppy how it feels, behavior is your thermometer. Research from the Institute of Canine Biology describes what to watch for in clear terms.
Cold puppies huddle tightly together in a pile. If they stay cold, they become agitated and cry out, but they don’t leave the pile. A single puppy that’s cold will swing its head from side to side, vocalizing with each breath, and may inch forward as if searching for warmth.
Overheated puppies also vocalize and swing their heads, which can look similar at first glance. The key difference: hot puppies move apart from each other and spread out across the whelping box. If you touch a hot puppy’s nose with your finger, it will pull away and turn its head, whereas a cold puppy will typically try to nuzzle toward the warmth of your hand.
Quiet puppies sleeping in a loose, relaxed group with some space between them are generally at a comfortable temperature.
Heating Methods and Safety
The most common heat sources for whelping boxes are heating pads, heat lamps, and space heaters that warm the room. Each comes with trade-offs.
Heating pads placed under part of the whelping box floor are popular because they provide steady, even warmth. Look for a pad designed for whelping that distributes heat across its entire surface. Cheaper pads can develop hot spots that burn delicate newborn skin. The pad should be sealed so puppies can’t chew into it or get wet from fluids. Place the pad under only one section of the box so puppies (and the mother) can move to an unheated area if they get too warm. This temperature gradient is important.
Heat lamps warm from above and are easy to adjust by raising or lowering the fixture. The risk is localized overheating, especially if the lamp is positioned too close. Puppies can’t move away effectively in the first few days, so monitor the surface temperature under the lamp with a thermometer rather than guessing.
Whichever method you use, keep a thermometer at puppy level inside the whelping box. The air temperature a few feet above the box can be very different from what the puppies actually experience on the floor.
Humidity and Dehydration
Warm environments dry out fast, and newborn puppies are vulnerable to dehydration. Keeping relative humidity in the whelping area around 55 to 65% helps prevent their skin and respiratory passages from drying out. A simple room humidifier works, and a basic hygrometer (available at any hardware store) lets you monitor levels. This matters most when you’re using heat lamps or forced-air heaters, which strip moisture from the air more aggressively than heating pads do.
The Room vs. the Whelping Box
There’s an important distinction between room temperature and whelping box temperature. Purdue University’s veterinary guidance recommends keeping the room at 75 to 80°F during the first week, while the whelping box itself should be warmer at 85 to 90°F. The room temperature matters because the mother dog spends time in and out of the box, and she can overheat if the entire room is kept at whelping-box levels. A room that’s too warm makes the mother restless and more likely to leave the puppies for extended periods.
Keeping the room moderately warm while boosting the box temperature with a localized heat source gives both the puppies and the mother what they need. As the puppies grow and the box temperature comes down over the following weeks, the gap between room and box temperatures naturally closes.