Cats often disguise the fact they are in pain. That may be because in the wild, cats that appear sick or injured are vulnerable to predators. You are in the best position to look for the subtle changes in behavior that may indicate your pet is suffering. It is important to stay alert to these signs, because the sooner your cat’s pain is diagnosed and treated, the sooner he or she can heal and resume a normal, happy life. When cats are in pain, they hide or become unsociable. They might hiss, meow or act unusually aggressive. Often they lick, bite or protect a certain part of their body or lose their appetite. If they have arthritis, they may walk stiffly or have trouble getting to their feet. They sometimes fail to groom themselves. A urinary infection may cause them to use the cat box more than normal. Look for these and other signs of unusual behavior.