While training a big dog to use an inside litter box can be a bit of a challenge, it’s sometimes the best option if your dog is elderly, if you're physically impaired or if you don't have regular access to an outside bathroom. Be prepared to have patience and persistence to make a smooth introduction to a litter box.
Pick a location. You want an area that's out of the way from your normal living space but that’s still easy for both you and your dog to access. If you have a large male dog, a corner location works well because you can put splash guards on the adjoining walls to protect against damage from urine spray.
Prepare the floors and walls. An indoor litter box for a big dog is going to be messy, at least during the training stages, so protect your home by putting down a tarp or plastic sheeting. Attach additional sheeting to the walls adjacent to the litter box as well. Heavy duty thumbtacks or staples should do the trick.
Purchase or repurpose a large, shallow plastic storage bin from a home improvement store, or use a large metal tray from the bottom of a large dog kennel. While you could theoretically build your own giant litter box from wood, it’s likely to retain odors and moisture and will quickly become ineffective.
Line the box with disposable puppy pee pads to make cleanup easier. Fill the box with traditional cat litter or buy dog litter from your local pet supply company.
Train your dog to the litter box. Some dogs may be hesitant at first, especially if they're used to going outside. You may even want to transition by placing the litter box outside where your dog normally makes his bathroom and get him used to the idea. Repetition and consistency is key. Offer treats and praise every time your dog uses the litter box.