"Baking soda can be used as a deodourizer to help keep the litter box smelling fresher," Dr. Barrack said. This is because bicarbonate of soda neutralises acids that are responsible for many unpleasant smells, Dr. Coates added. You should sprinkle some bicarbonate of soda on the bottom of your freshly cleaned litter box, then add new litter on top. "As your cat digs around the box, she'll mix a little bicarbonate of soda into the litter as she goes," LaFontaine said. "You can add a little more fresh bicarbonate of soda every time you scoop, too."