According to Dr. Natalie Marks, a veterinarian from the Blum Animal Hospital in Chicago, when cats spray outside the house, it’s completely normal behavior. When they spray inside, however, it should raise a little red flag in your head, because it can be indicative of a behavioral or medical problem. So, when you first see your cat starting to spray indoors, Dr. Marks recommends you contact your veterinarian. She says that the most common medical reason for cat spray is FLUTD (feline lower urinary tract disease), which is a painful inflammation. One of the symptoms of such inflammation is urine spraying (and subsequently ruined upholstery). Your vet should be able to treat FLUTD or rule it out.
But there are other reasons too
Dr. Marks explains that urinary spraying can also be caused by mental states such as stress and anxiety. Things that can commonly trigger such a mental state with your cat could be an unfamiliar location; like moving into a new place or waiting for the cat to get used to your house right after adoption. A vet could help you identify and remove such triggers. In addition, you should ask your vet about pheromone treatment. Those relaxing compounds for pets are usually sold as wipes or diffusers and help reduce anxiety. Lastly, Dr. Marks recommends that you clean up the areas that have been sprayed with a special enzymatic cleaner. This cleaner will help you get rid of the smell as well as the bacteria that might have infected your kitty in the first place.