hi! I know that a lot of dogs can be litter box trained and I bet pugs can too, they can be newspaper trained so why not litter box trained! It might take some extra work but they would catch on after seeing the cats doing it you would think! Puppy pads would work too...they might catch onto that faster than litter boxes. I dont have experience with litter box training dogs though..all my dogs are over 40 pounds!! (Is there a litter box that big?...)