Cats will also caterwaul, display frenzied behavior and spray urine for another reason. Your female cat may be in heat. Your unneutered male cat may be responding to neighborhood female cats in heat. Spaying is a surgical procedure that entails the removal of the ovaries and uterus. Because of the cat's unique sexual physiology, they usually become pregnant each time they mate.
Many cats get pregnant without their owner even realizing that they have been in heat to begin with.
In addition, spaying removes the annoying behaviors that are characteristic of being in heat. If the female cat is prevented from mating, she will not ovulate. Consequently, the heat period may wax and wane for several weeks. During this time, she will often go off her food and become hyperactive. She may stop using her litterbox.