Spayed or Neutered
Also better behaved. Female dogs are in heat for about 21 days twice a year. Cats are less predictable, but can be in heat 3-15 days, 3 or more times a year. If you've seen them go through this, you've seen them suffering. They cry, pace and try to get out. Dogs in heat produce a bloody discharge that can stain rugs and furniture and attracts male dogs. If this rubs off on you, you may find yourself pursued by canine admirers yourself.
For male cats, neutering stops spraying, the cat's foul-smelling marking of territory. It may not always stop it, however, if the habit is already established, which is why they should be neutered before they start spraying.
Dogs, too, mark territory, producing yellow spots on hubcaps, shrubs, etc. Neutering dogs ends mounting behavior on furniture and people's legs, something not generally appreciated by most guests.
For dogs and cats neutering reduces the urge to roam and fight and their lower aggression level makes them much better pets.
If you think pets enjoy and active sex life the way humans do, think again, and be sure to read Myths.