# How to set up a whelping box: size, spot, heat and bedding > How to set up a whelping box for a dog: how big it should be, where to put it, temperature by week, bedding choices, rails, and when to let her get used to it. Canonical: https://lucernel.com/guides/how-to-set-up-a-whelping-box Last updated: 2026-10-14 Type: Guide. Publisher: Lucernel. ## Short answer Set the whelping box up in a quiet, low-traffic spot at least two weeks before the end of the pregnancy so she can get used to it. Make it about one and a half times her body length, with a rail around the edge and an opening she can step through, and keep the newborns’ box area warm: about 85 to 90°F in the first week, lowering each week. Ask your vet about anything specific to your dog. - **Choose this if:** Use this checklist if you have a pregnant dog and about two weeks to set up. - **Choose the other option if:** Littero helps with the schedule around the box: the expected whelping window, reminders for key dates and each puppy’s weigh-ins once they arrive. ## Side by side | | Heating pad | Overhead heat lamp | | --- | --- | --- | | Can burn puppies | Yes, if it gets too hot or they cannot move away | Yes, if too close, so keep it at a suitable distance | | Fire hazard | Not listed by Purdue | Yes, Purdue lists a potential fire hazard | | Needs a safety feature | Yes, a low setting or automatic shutoff | Partly, keep it at a safe distance and check the heat with a thermometer | | Preferred form of heat in the Merck manual | No, it warns of burns in neonates that cannot move away | Yes, an overhead lamp at an appropriate distance | | Affordable | Yes, small and affordable | Yes, affordable | ## Pick the spot first Purdue’s Croney Research Group says dams need a quiet, calm place to give birth, away from barking dogs and noise, in a low-traffic area. She should still be able to go outside to eliminate and exercise, and to have known, trusted handlers around. The Merck Veterinary Manual says dogs should deliver in a familiar area where they will not be disturbed, because unfamiliar surroundings or strangers may hinder delivery and affect maternal instincts, especially in a first litter. VCA Animal Hospitals adds that some dogs insist on whelping near their owner, and that it is less stressful to let her continue in the place she picked, covered with newspaper or bedding, then gently move her and the puppies afterward if she allows. ## Size: one and a half times her body length Purdue says the box should be large enough that the dam can relax and stretch out, and suggests one and a half times your dog’s body length. VCA says it should be large enough for her to move freely, with low sides so she can see out and easily move in and out. For a small dog, VCA says a large cardboard box with an open top and an opening cut out of the side works well. Our arithmetic: a dog that measures 30 inches lying stretched out needs a box about 45 inches long. Measure her yourself instead of using a breed chart. The box must also keep puppies from wandering, so the opening should be low enough to step through but not wide open. ## Material, rail and edges Purdue says a box must be sanitized between dogs and litters, so choose a non-porous surface such as plastic or plexiglass. The ideal box has a railing, known as a pig rail, around the edge, which prevents the dam from accidentally lying on her puppies. Sharp edges can injure her mammary glands and put her at risk of infection (mastitis), so keep the box clean and free of rough edges. Purdue also notes an easy, affordable option: a plastic kiddie pool with a pool noodle zip-tied around the edge as a rail. ## Temperature by week Newborns cannot hold their own temperature. The Merck manual says puppies lack thermoregulation until 4 weeks, lists an environmental temperature of 84 to 89°F in week 1, 80°F in weeks 2 and 3, and 69 to 75°F in week 4, and recommends 55 to 65% humidity. Purdue lists box temperatures of 85 to 90°F in week 1, 80 to 85°F in week 2 and 75 to 80°F in week 3, with a room at 75 to 80°F, 70 to 80°F and 70 to 75°F. VCA says to keep the box at about 85 to 90°F during the first few days. The sources differ by a few degrees, so a thermometer at puppy level and a vet’s advice beat a single number. Puppies and the dam need room to move away from heat, since the dam may need cooler areas and newborn puppies are not strong enough to leave a hot spot. Seal drafts around doors and windows, as Purdue advises. VCA adds that when the dam cares for her puppies and the room is warm, extra heat is usually unnecessary, and that with a heat lamp both she and the puppies can overheat, so check the temperature with a thermometer. ## Bedding that stays dry and safe Purdue advises absorbent, non-slip bedding with puppy pads or newspapers under it. Its comparison: puppy pads, shavings and newspaper are absorbent and cheap but slippery; carpet is non-slip but cannot be disinfected and can fray and trap toes; towels and blankets wash well but puppies can get tangled and a digging dam can crush them; fleece-type bedding is comfortable and washable but costs more. Our advice: start with newspaper or pads under washable bedding that is easy to change, and change soiled layers quickly. VCA notes that acrylic bedding washes easily and can cover newspaper, but that plain newspaper is more absorbent and puppies are less likely to get hidden beneath it. Clean the whole area daily, as Purdue suggests. ## When to set up and how to introduce it Purdue advises setting up the area at least two weeks before the end of pregnancy. Merck puts the due date 62 to 64 days from ovulation, so by our arithmetic that is about day 48 to 50 if you count from ovulation, and earlier if your dates are uncertain. Put the box where it will stay and let her sleep and eat near it. Checklist from the sources: a quiet spot, a box sized to her, a rail, a non-porous surface that can be sanitized, absorbent bedding, a safe heat source with a thermometer, and draft-proofing. Our addition: write your vet’s and an emergency clinic’s numbers where you can see them. Disclosure: Littero is made by Lucernel, the publisher of this article. ## Frequently asked questions ### How big should a whelping box be? About one and a half times the dog’s body length, according to Purdue’s Croney Research Group, so she can stretch out. It should also have low sides or an opening she can step through easily. ### When should I set up the whelping box? At least two weeks before the end of the pregnancy, per Purdue, so she can get used to it. Pregnancy lasts 62 to 64 days from ovulation, according to Merck. ### How warm should a whelping box be? About 85 to 90°F in the first week, then lower each week. Purdue lists 80 to 85°F in week 2 and 75 to 80°F in week 3, while Merck lists 80°F for weeks 2 and 3. ### What bedding is best in a whelping box? Absorbent, non-slip bedding over puppy pads or newspaper. Purdue notes that towels and blankets can tangle puppies or be crushed by a digging dam, and carpet cannot be disinfected. ### Is Littero available? See the official app page for current availability and pricing. ## Our pick: Littero, the dates around the box The box is only one part of a litter. Littero shows the pregnancy from mating to whelping as an expected window, never a single fake date, sends reminders for key dates including whelping, and keeps each puppy’s weigh-ins and documents once they are born. The record stays on the device and works offline, and you can export it for your vet. It does not replace your veterinarian’s advice. - Whelping date as a range with its uncertainty - Reminders for key dates, tests and vet visits - Puppy weigh-ins and documents from birth [See how Littero works](https://lucernel.com/apps/littero) ## Sources (checked 2026-10-01) - [Purdue Croney Research Group: Setting up a welfare-friendly whelping area](https://caninewelfare.centers.purdue.edu/resource/setting-up-a-welfare-friendly-whelping-area/) - [Merck Veterinary Manual: Management of the neonate in dogs and cats](https://www.merckvetmanual.com/management-and-nutrition/management-of-the-neonate/management-of-the-neonate-in-dogs-and-cats) - [Merck Veterinary Manual (owners): Management of reproduction in dogs](https://www.merckvetmanual.com/dog-owners/reproductive-disorders-of-dogs/management-of-reproduction-in-dogs) - [VCA Animal Hospitals: Whelping in dogs](https://vcahospitals.com/know-your-pet/whelping-in-dogs)