Standard Poodle Q&A
Yes! My 2.5-year-old female pap uses a litter box with dog litter. The breeder litter trains all her dogs, and it made great sense, so we went along with her direction. It was not hard at all. Our pap will go outside also, but when it is cold, raining, or I need to be out for an extended period, she has her box in the corner of her x-pen I keep in my office. She knows what to do, and I never need to rush home or worry about accidents ever.
Litter box training is a great option for Papillons. But DO NOT expect them to use the same litter box as your cats. All dogs love to eat cat feces, so you should keep your cat's litter box in a place your dog can't get to. Plus, I imagine your cats might get perturbed with the strange smells of dog excrement in their box. Give your dog his own box with dog specific litter.