"The most widespread form of interspecies bonding occurs between humans and dogs" and the keeping of dogs as companions, particularly by elites, has a long history. (As a possible example, at the Natufian culture site of Ain Mallaha in Israel, dated to 12,000 BC, the remains of an elderly human and a four-to-five-month-old puppy were found buried together). However, pet dog populations grew significantly after World War II as suburbanization increased. In the 1950s and 1960s, dogs were kept outside more often than they tend to be today (using the expression "in the doghouse" to describe exclusion from the group signifies the distance between the doghouse and the home) and were still primarily functional, acting as a guard, children's playmate, or walking companion. From the 1980s, there have been changes in the role of the pet dog, such as the increased role of dogs in the emotional support of their human guardians. People and dogs have become increasingly integrated and implicated in each other's lives, to the point where pet dogs actively shape the way a family and home are experienced.
Wolves, and their dog descendants, likely derived significant benefits from living in human camps – more safety, more reliable food, lesser caloric needs, and more chance to breed. They would have benefited from humans' upright gait that gives them larger range over which to see potential predators and prey, as well as better color vision that, at least by day, gives humans better visual discrimination. Camp dogs would also have benefited from human tool use, as in bringing down larger prey and controlling fire for a range of purposes.
^ Wood, Lisa; Martin, Karen; Christian, Hayley; Nathan, Andrea; Lauritsen, Claire; Houghton, Steve; Kawachi, Ichiro; McCune, Sandra (2015). "The Pet Factor – Companion Animals as a Conduit for Getting to Know People, Friendship Formation and Social Support". PLoS ONE. 10 (4): e0122085. Bibcode:2015PLoSO..1022085W. doi:10.1371/journal.pone.0122085. PMC 4414420. PMID 25924013.
Dogs are highly variable in height and weight. The smallest known adult dog was a Yorkshire Terrier, that stood only 6.3 cm (2.5 in) at the shoulder, 9.5 cm (3.7 in) in length along the head-and-body, and weighed only 113 grams (4.0 oz). The largest known dog was an English Mastiff which weighed 155.6 kg (343 lb) and was 250 cm (98 in) from the snout to the tail. The tallest dog is a Great Dane that stands 106.7 cm (42.0 in) at the shoulder.
The health benefits of dogs can result from contact with dogs in general, and not solely from having dogs as pets. For example, when in the presence of a pet dog, people show reductions in cardiovascular, behavioral, and psychological indicators of anxiety. Other health benefits are gained from exposure to immune-stimulating microorganisms, which, according to the hygiene hypothesis, can protect against allergies and autoimmune diseases. The benefits of contact with a dog also include social support, as dogs are able to not only provide companionship and social support themselves, but also to act as facilitators of social interactions between humans. One study indicated that wheelchair users experience more positive social interactions with strangers when they are accompanied by a dog than when they are not. In 2015, a study found that pet owners were significantly more likely to get to know people in their neighborhood than non-pet owners.
Neutering refers to the sterilization of animals, usually by removal of the male's testicles or the female's ovaries and uterus, in order to eliminate the ability to procreate and reduce sex drive. Because of the overpopulation of dogs in some countries, many animal control agencies, such as the American Society for the Prevention of Cruelty to Animals (ASPCA), advise that dogs not intended for further breeding should be neutered, so that they do not have undesired puppies that may later be euthanized.
Amongst apprenticeship programs and other hands-on training activities, Petco pet stylists who are trained from within the company are required to attend and pass Petco's comprehensive 12-week Pet Stylist Apprentice & Certification academy program. In addition to hands-on grooming training with a Petco-certified pet stylist mentor or instructor, all participants receive instruction in health, safety protocols and grooming salon operations. At the end of the program, candidates must pass a technical skills assessment in order to become a Petco Certified Pet Stylist.