A whelping box is used as an enclosed space where a female dog whelps, or delivers, her puppies. The area is also used for the dog and litter for the first weeks of the puppies' lives and should provide a warm and dry space for them during this time. The size of the whelping box is determined by the size of the mother dog. The material used to make a whelping box can vary.
Wood is probably the most common whelping box material, especially with do-it-yourself dog owners. The Devine Farm website suggests using 3/4-inch plywood for whelping boxes used by mastiffs. Insulation can be placed under the whelping box if it will be on a cold floor. Three sides of the box are usually built high enough to keep the mother dog from jumping in those directions. The front side is low enough for the dog to exit the box but high enough to keep in the puppies. Seal the wood with paint or sealant before use.
Disposable cardboard whelping boxes are available from commercial sources. These boxes have the advantage of starting out clean for each birthing process. The boxes are usually a sealed cardboard and should be monitored for chewing and other damage from the dog.
The bottom half of a dog crate or carrying kennel also works well as a whelping box, according to the website Whelp Wise. The boxes are available in a variety of sizes to fit most breeds of dogs. Depending on the height of the lip of the front of the dog crate, a piece of wood or cardboard may need to be added to prevent puppies from crawling out of the box.
Plastic Kiddie Pools
Some large dog breeders have used plastic wading or swimming pools for whelping boxes. The pool can be cut down in one area to provide an access point for the dog. Plastic pools have an advantage of being easily cleaned and disinfected.
Although more commonly used once the puppies are a little larger and capable of moving around, a child’s play pen can be used as a whelping box if the sides are covered with blankets to provide some privacy for the dog. Play pens often have gates that would need to be opened to allow the dog to exit the whelping box.