In a study of seven breeds of dogs (Bernese mountain dog, basset hound, Cairn terrier, Epagneul Breton, German Shepherd dog, Leonberger, and West Highland white terrier) it was found that inbreeding decreases litter size and survival. Another analysis of data on 42,855 dachshund litters found that as the inbreeding coefficient increased, litter size decreased and the percentage of stillborn puppies increased, thus indicating inbreeding depression. In a study of boxer litters, 22% of puppies died before reaching 7 weeks of age. Stillbirth was the most frequent cause of death, followed by infection. Mortality due to infection increased significantly with increases in inbreeding.
The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This influence on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are also a source of meat.
Dry your dog. Use a squeegee or use your hand as a squeegee to force water off of the coat and body. Towel dry him as best as you can while he's still in the tub, so you don't make a mess. Place the towel over your dog’s back, or hold it next to him and give permission to shake the water off their body. Many dogs will learn the “bath rules” and wait to shake until you have placed the towel over them to contain the water droplets. Another type of towel to use is a chamois, which is a thin fleece like towel that is designed to be wrung out when wet. It lessens the amount of towels needed and does the bulk of the work. Using a chamois, then a towel makes drying less of a hassle.
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.
According to the Humane Society of the United States, 3–4 million dogs and cats are euthanized each year in the United States and many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or castrating dogs helps keep overpopulation down. Local humane societies, SPCAs, and other animal protection organizations urge people to neuter their pets and to adopt animals from shelters instead of purchasing them.
Some breeds of dogs are prone to certain genetic ailments such as elbow and hip dysplasia, blindness, deafness, pulmonic stenosis, cleft palate, and trick knees. Two serious medical conditions particularly affecting dogs are pyometra, affecting unspayed females of all types and ages, and gastric dilatation volvulus (bloat), which affects the larger breeds or deep-chested dogs. Both of these are acute conditions, and can kill rapidly. Dogs are also susceptible to parasites such as fleas, ticks, mites, hookworms, tapeworms, roundworms, and heartworms (roundworm species that lives in the heart of dogs).