Dogs developed a symbiotic relationship with humans by scavenging human campsites for food. They provided a waste disposal function and alerted humans to intruders, leading humans to domesticate them as companions and guards. There are now around 5.9 million dogs in Canada. Cats have also been companions for at least 9,500 years and are popular pets, with 63 million worldwide and 7.9 million in Canada. They control pests and require less care than dogs but still need attention, play, and medical care to live healthy, happy lives.