Retraining your cat after a Medical problem has been identified and solved

If your cat has experienced painful urination or defecation in the box due to a medical problem, such as crystals or a urinary tract infection, he may associate the box with pain and avoid it. This may continue after the health problem is treated. Read below for possible solutions that may apply, including tips on dealing with surface and location preferences.

Try to build new positive associations with the litter box by:

Buying a new box, using a different type of litter, and placing it in a new area of the home if possible
Scooping the box a minimum of once daily and changing the litter twice a week (more if it's scoopable litter) instead of just topping up the litter
Using soap and water to clean the box (Bleach and other chemicals leave a residue that we cannot smell but will repel the cat)
Switching to a non-scented or deodorized litter and move any air fresheners away from the box. (Note: To help absorb odours you can place a thin layer of baking soda along the box's bottom - however, if you find the box smelly it's likely your cat will too)
There are many new litters on the market that are manufactured to attract cats to the litter box
Ensuring the box is far from appliances or areas where sudden loud noises are common. Moving the box to an area where the cat has more than one exit point (if the cat was previously "ambushed" when using the box and is leery of being cornered)
Returning to your regular litter brand/type (research has shown most cats prefer fine-grained litters)
Switching from a closed box to an open box (due to their highly sensitive sense of smell, many cats dislike covered boxes where odours are trapped inside

Pointers on retraining your cat

To help with retraining, a program of confinement and supervised freedom is often recommended. Start by keeping your cat confined to a small room, such as the bathroom, where the cat has fewer opportunities to make mistakes but is also not isolated for extended periods of time (since it's an essential room everyone visits). Make sure you spend three or four 20-minute sessions during the day to visit, feed, talk, play and groom your cat. Place a cat bed, toys and dishes in the corner farthest from the litter box. In some cases, the cat may need to start in a cattery cage or dog crate to ensure he has no opportunity for a mistake. Place the cat bed at one end and the litter box at the other. Remove the bed if it is urinated on. Feed the cat two meals daily and leave the food for approximately 20 minutes. Keep a journal of when your cat uses the litter box.

After your cat has used the litter box reliably in his confined space for two weeks, start to allow him access to other rooms in the house, ideally one room at a time. At first he should only be out when you are around the house to supervise and help ensure he doesn't make a mistake. The best time to let him roam at this stage is after he's just used his box. Once you observe the cat reliably returning to his litter box under supervised freedom, you can reduce the supervision. Take it slow and be consistent. When you see your cat using the box, praise and/or give a treat immediately after. If you catch your cat in the act outside of his litter box, do something to interrupt him like making a startling noise, but be careful not to scare him. Quickly take him to the litter box and set him nearby. If he goes over to the litter box and eliminates, praise him. If instead, he wanders away, he may want privacy. Keep watch from a distance and praise when he uses it.

Never punish your cat for eliminating outside the box. If you find a soiled area, simply clean it up as described below. Compassion, consistency, patience and persistence will be rewarded in time. For long-term or complex situations contact an animal behaviour specialist who is experienced working with cats. If environmental and behavioral modification do not resolve the problem, pharmacological intervention may be necessary. Speak with your veterinarian.