His tail may quiver, and the cat my alternately lift his hind paws while spraying. Male, female, spayed or neutered, cats of any age may spray, although the behaviour is most common in unneutered males. Discouraging the presence of neighbourhood cats. Try blocking off windows where your cat can see neighbourhood cats. Resolving conflicts between cats in your household.
Stress is often behind house-soiling, particularly spraying.
A new baby, a new pet, moving or subtle changes in your lifestyle can also be very stressful to your cat. For some reason, your cat has decided that the litter box is an unpleasant place to be. This is a common cause of cats abandoning the box. Change back to the litter your cat used before. Another reason is new scents in or around the box.