Dogs are adaptable animals. For the last 14,000 years they have learned how to live with humans around the world. Most pet dogs live in the same environment as their masters, but their needs vary with breed and size. Toy dogs and small dogs are often content to live mostly indoors and in small spaces. Medium and large dogs, such as a greyhound or a Saint Bernard, need more space and exercise. They need to be walked outdoors at least twice a day on a leash and, if possible, let loose to run and play in a closed yard or a field in the countryside.
A dog’s personality usually depends on the breed of the dog. For instance, herding dogs such as the Border Collie or a Jack Russell terrier have a lot of energy. This means they may need more exercise than a lower-energy dog like a pug. Dogs enjoy the company of other dogs. Walking is important because it allows dogs to meet other dogs. Many communities, such as cities where there may not be a lot of green space, have established special dog parks. They are enclosed outdoor spaces meant just for dogs and their owners. Dogs can be unleashed and are free to run and play with other dogs. Dog owners can enjoy meeting other dog owners, too. Most domestic dogs do not have to worry about predators. But in areas near forests or other wilderness regions, wild animals can be a threat. Dogs, especially small ones, have been killed by wild animals such as coyotes, wolves, bears, and mountain lions. People who live in areas where these wild animals have been seen should keep a close eye on their pets and not let them roam outside their yard. Pets should be kept indoors at night in order to avoid being stalked by predators at that time.
Dogs and people have been getting along as good friends for a long time. Most of us require nothing
more from our “best friends” than a wagging tail and a lot of love. But there are many dogs that do much more to earn their keep and their masters’ love. Sporting dogs—including pointers, retrievers, and setters—help hunters find game birds and then fetch or retrieve them. Hounds with their keen sense of smell can also aid hunters. Dogs help law enforcement agencies to sniff out drugs and other illegal goods that people carry with them into airports and other places. Saint Bernards help search for and rescue people in trouble. Alaskan huskies pull sleds carrying people and goods in the frozen northern part of the world. Doberman pinschers guard homes and property against intruders.
German shepherds and other super-intelligent dogs work as Seeing Eye dogs, guiding blind and visually impaired people. Collies herd animals such as cattle and sheep. Terriers were once used to catch rodents.
Most people treat their dogs well, but some people mistreat and abuse dogs. A mistreated dog may become dangerous to other people. It might attack or bite without warning. It is not the dogs that are bad; it is people who train them to do bad things. Other people think they are being good to their dogs 
when they are actually being cruel. Such people allow their dog to mate with another dog and have babies. Because of this, many unwanted dogs are brought into the world each year. Many of these dogs are abandoned to live on the streets, and they become a public nuisance and a health hazard. Many abandoned dogs end up in animal shelters. If nobody adopts these dogs within a certain time period, they are put to sleep and destroyed. Millions of dogs in the United States face this fate each year.
Veterinarians and animal rights organizations strongly recommend that new dog owners have their dogs operated on at an early age to prevent them from having babies. In females, this simple operation is called spaying, and in males it is called neutering. The operation not only helps control the dog population but also benefits the dog. He or she stays calmer, less aggressive, and often healthier in old age than dogs without the operation. All these things make for a better family pet. Keeping a dog is a big responsibility. It requires patience, love, and hard work. But what you get in return is a friend for life.