Tom cats spray to mark their territory -- to let other cats know who is in charge of a particular turf. While neutering a tom cat often eliminates urine spraying, that's not true in every case. If your neutered cat starts spraying, there's generally a physical or emotional reason for his behavior. Start out with a trip to the vet. If your vet can't determine a physical reason for the spraying, some sort of anxiety is likely plaguing your pet.
Your vet will take a blood and urine sample from your cat for analysis, as well as give him a thorough physical examination. Medical reasons for spraying include urinary tract infections, bladder stones and cystitis. Cats suffering from kidney disease, hypothyroidism or diabetes might start spraying. Your vet will treat your cat for the diagnosed condition -- such as prescribing antibiotics for a urinary tract infection -- and you can monitor your cat while he's under treatment to see if spraying stops or is significantly reduced.
Litter Box Changes
If no physical cause is found for your cat's spraying, you might start making some physical changes in your house to see if you can stop his inappropriate elimination. If you have multiple cats and room permits, provide one litter box per cat and one extra. Cats like privacy, so try putting boxes in out-of-the-way places. Experiment with different types of litter in case your spraying cat has a preference. Keep all boxes scrupulously clean. If you can, place a litter box in the area where the cat most often sprays.
Look for Triggers
Try to get inside your cat's head and figure out what triggers his spraying. Do outside cats come to the window and taunt him? Does he frequently have conflicts with other feline or canine members of the household? Consider any changes in the household, including new family members or pets, a move to a new residence, or even a recent furniture rearrangement. By spraying, your cat is trying to tell you something is bothering him. If a strange cat is coming around, closing the curtains might solve the problem. If cats fight with each other, try keeping them as separate as possible, including different feeding areas and litter box sites.
Your vet might prescribe anti-anxiety medications -- many of the same drugs used for people -- if she suspects the reasons your cat sprays is primarily emotional. Kitty might receive fluoxetine, marketed under the brand name Prozac, or paroxetine, sold under the trade name Paxil. An older tranquilizer, diazepam, better known as Valium, is also used for felines. Clomipramine, a tricyclic antidepressant used for treating people with obsessive-compulsive issues, seems to aid cats with spraying problems. Your vet will decide which of these medications best suits your cat, as some are not appropriate for cats with underlying liver or heart disease. While many cats respond well to medication, some cats resume spraying once the drug is stopped.