Why does a cat suddenly start defecating in the wrong places?

A cat suddenly defecating in the wrong places may be caused by health problems, external stimuli, emotional stress, estrus, and other reasons. If the cat has a urinary system problem, inappropriate defecation may appear. When a cat is overstimulated or under too much stress, such as a noisy living environment or being frightened, it may also defecate inappropriately. In addition, cats in heat usually relieve themselves around the house and show other signs of estrus.