The size of the litter box can play a role in litter box odour. Dr. Barrack recommends getting a box that is bigger than your cat. "A box that is too small means your cat will not have enough personal space and may leave feces in places they shouldn't, including next to the box," she said. Additionally, "A larger box could help with odours by potentially reducing the chances that urine or feces would become stuck on the sides or bottom," Dr. Coates added. This is because a large box has more litter; therefore, more liquids will be absorbed and solids will be covered, LaFontaine explained.