The best way to keep odour to a minimum is to clean the litter box consistently and as frequently as possible, said Rachel Barrack, DVM, CVA, CVCH and founder of concierge practice, Animal Acupuncture. "Scoop at least twice per day," LaFontaine said. "By removing the liquids and the solids in the pan, you're removing the source of the odour. You're also keeping your cat happily using the pan. The only thing that can smell worse than a dirty litter box is the smell when a cat starts refusing to use the litter box." Jennifer Coates, DVM, serves on the advisory board for Cat Life Today, explained that the more urine and feces in the box, the more it's going to smell. "Also, the smells associated with urine get worse over time as bacteria start to break it down," she said.