Here is the new whelping pen / whelping kennel I built. The whelping kennel is 5 foot wide by 7 foot long by 4 foot tall made from a PetSafe Cottageview Dog Wired Kennel with an extension kit. Each kennel panel section is 27.5" wide.
The railing panels inside the whelping kennel are 12" tall. All railing panels slide in place, so need to have to screw them in place. It has a removeable center railing panel that can be pulled up when pups age to give more room. The backing on some of the kennel sections is coroplast. The flooring of the whelping kennel is horse stall mats. The hog rails are made from PVC piping.