A pet or companion animal is an animal kept for companionship and enjoyment, as opposed to livestock, laboratory animals, working animals or sport animals, which are kept for economic reasons. The most popular pets are noted for their loyal or playful characteristics, for their attractive appearance, or for their song. Pets also generally seem to provide their owners with non-trivial health benefits; keeping pets has been shown to help relieve stress. There is now a medically-approved class of "therapy animals," mostly dogs, who are brought to visit confined humans. Walking a dog can provide both the owner and the dog with exercise, fresh air, and social interaction.
While in theory any animal might be a pet, in practice only a small number of species of mammals (especially dogs and cats) and other small animals, such as birds, fish, or lizards, are practical. One reason for this is that large animals are not able to fit inside small dwellings.
In general, a pet must either be small enough (or easily controlled) for his or her undesirable behavioral tendencies to be negligible, or the animal must be actually domesticable.
A few animals are sufficiently capable of adapting to human interaction to be considered domesticable. Dogs ("man's best friend") are considered to be a classic example of domesticated animals normally suited to being pets. Domestic dogs are quite similar to wolves, but their physical form and behavior are characteristically different, more than mere differences in size, coat, or coloring. Behaviorally speaking, characteristic changes in dogs due to domestication include a prolonged infancy, increased playfulness, and increased barking. Wolves are far less playful and vocal.
Many rodents, such as fancy rats, fancy mice, and Syrian hamsters, are commonly kept as household pets. Such animals as reptiles are typically considered exotic pets. This may change in the future, as 'exotic' pet ownership is increasing rapidly. Some of these animals, such as green iguanas, large monitor lizards, and large birds, do not make suitable pets for the average person, as they require extensive housing and diet. They can also become quite aggressive if not regularly handled. Exotic mammals are also becoming increasingly more popular as pets. A pet can be acquired from an animal shelter, a breeder, and from private transactions, typically due to the giving away of extra newborns after the birth of a litter.
Health Benefits of Having a PetPets have the ability to stimulate their caregivers, in particular the elderly, giving people someone to take care of, someone to exercise with, and someone to help them heal from a physically or psychologically troubled past. Having a pet may help people achieve health goals, such as lowered blood pressure, or mental goals, such as decreased stress. There appears to be strong evidence that having a pet can help a person lead a longer, healthier life. In a study of 92 people hospitalized for coronary ailments, within a year, 11 of the 29 without pets had died, but only 3 of the 52 who had pets.
Even pet owners residing in a long-term care facility, such as a hospice or nursing home, experience health benefits from pets. Pets for nursing homes are chosen based on the size of the pet, the amount of care that the breed needs, and the population and size of the care institution. Appropriate pets go through a screening process and, if it is a dog, additional training programs to become a therapy dog.