In ancient Egypt dogs were thought to possess godlike characteristics. They were pampered by their own servants, outfitted with jeweled collars, and fed the choicest diet. Only royalty was permitted to own purebred dogs, and upon the death of a ruler his favourite dog was often interred with him to protect him from harm in the afterlife.
Once it became evident that dogs were faster and stronger and could see and hear better than humans, those specimens exhibiting these qualities were interbred to enhance such attributes. Fleet-footed sight hounds were revered by noblemen in the Middle East, while in Europe powerful dogs such as the mastiff were developed to protect home and traveler from harm.
As society changed and agriculture—in addition to hunting—became a means of sustaining life, other breeds of dogs were developed. Herding and guarding dogs were important to farmers for protecting their flocks. At the same time, small breeds became desirable as playthings and companions for noble families. The Pekingese in China and fragile breeds such as the Chihuahua were bred to be lapdogs. The terrier breeds were developed, mainly in England, to rid granaries and barns of rodents. Pointing and retrieving breeds were selected for special tasks related to aiding the hunter to find and capture game. Many breeds are extremely ancient, while others have been developed as recently as the 1800s.
Dogs come in a wide range of shapes and sizes. It is difficult to imagine that a large Great Dane and a tiny poodle are of the same species, but they are genetically identical with the same anatomic features. All dogs have 78 chromosomes, or 39 pairs of chromosomes (humans have 23 pairs), and one member of each pair comes from each parent. The normal temperature (rectal) of an adult dog is 100–102.5 °F.
Dogs have played an important role in the history of human civilization and were among the first domesticated animals. They were important in hunter-gatherer societies as hunting allies and bodyguards against predators. When livestock were domesticated about 7,000 to 9,000 years ago, dogs served as herders and guardians of sheep, goats, and cattle. Although many still serve in these capacities, dogs are mainly used for social purposes and companionship. Today dogs are employed as guides for the blind and disabled or for police work. Dogs are even used in therapy in nursing homes and hospitals to encourage patients toward recovery. Humans have bred a wide range of different dogs adapted to serve a variety of functions. This has been enhanced by improvements in veterinary care and animal husbandry.
Although it’s hard to imagine, dogs have long been used as research and testing subjects. In fact, in 1883, AAVS was founded specifically to protect dogs from being stolen or otherwise collected off the streets so they could be used in research, often suffering in agony with no analgesic or pain relief. This continued through the first half of the 20th century without regulatory oversight, until 1966 when the Animal Welfare Act (AWA) was enacted, spurred in part by the death of Pepper, a Dalmatian who was stolen from her family in Pennsylvania, transported to New York, sold to a lab by an animal dealer, and then killed during an experiment. Although animal research and testing are now regulated, the AWA does not restrict the use of certain types of animals, including pets, and dogs are still used in experiments today.
Several years ago, facilities could purchase dogs from random source Class B dealers, who acquire animals from pounds and shelters and then sell them for use in research. Random source dealers have had a long sordid history of violating the AWA. So, Congress directed the National Institutes of Health (NIH) to determine the importance of dogs and cats purchased from random source Class B dealers in biomedical research. The resulting 2009 report from the Institute for Laboratory Animal Research concluded that “it is not necessary to obtain random source dogs and cats for NIH research from Class B dealers.” In 2011, the National Institutes of Health announced that it would start to phase out funding for research using dogs and cats obtained from random source Class B dealers. This policy came into full effect for dogs in October 2014, and for cats in October 2012.
Dogs are often used in biomedical research investigating heart and lung disease, cancer, and orthopedics. They are also used in toxicity studies to test the safety of drugs and industrial chemicals, but are rarely used to assess the safety of personal care and household products. Most dogs used in research are purpose-bred in laboratories or by private companies that sell strictly to labs. Dogs can be bred to be pathogen-free or genetically manipulated to be a model of human disease.
The most common breed of dog used for experiments are beagles, but not because scientists view them as the best model for human disease. Rather, beagles are convenient to use because they are docile and small, allowing for more animals to be housed and cared for using less space and money.
To acquire dogs with specific traits who are not readily available from breeders, some research facilities obtain dogs directly from pounds and shelters, a practice called pound seizure. These labs may want older dogs to use in age related research or large dogs to study heart disease. Also, medical and veterinary schools have traditionally used dogs from shelters for student training, particularly for surgery. Now the trend is to utilize alternatives that do not harm animals and allow veterinarians to gain experience through beneficial shelter medicine programs.
The term “domestic dog” refers to any of several hundred breeds of dog in the world today. While these animals vary drastically in appearance, every dog—from the Chihuahua to the Great Dane—is a member of the same species, Canis familiaris. This separates domestic dogs from wild canines, such as coyotes, foxes, and wolves.
While it’s impossible to say exactly how a wild wolf species became a domesticated dog, most scientists believe the process happened gradually as wolves became more comfortable with humans. Perhaps wolves started down this path simply by eating human scraps. Many generations later, humans might have encouraged wolves to stay near by actively feeding them. Later still, those wolves may have been welcomed into the human home and eventually bred to encourage certain traits. All of this is thought to have unfolded over thousands of years.
This is why animal handling expert Jack Hanna recommends teaching children to always exercise caution around a dog they do not know. For instance, he says kids should ask for permission from the dog’s owner before trying to pet or play with the animal. Offering an outstretched hand also allows the dog to familiarize itself with a new person before reaching behind its head where it can’t see what you’re doing, which might make a dog nervous or scared. Finally, never allow children to put their faces near the dog’s muzzle.
They assist search and rescue teams in the wake of natural disasters or reports of people lost in the outdoors. Dogs trained to warn of hidden explosives and enemies serve as allies in military operations. Other dogs assist police looking for jail escapees or the bodies of murder victims. Some partner instead with customs officials searching for contraband, from drugs to elephant ivory. Still others lead the way tracking down poachers, patrolling cargo ships for rats that might escape at distant harbors, or exposing forest insect pests in shipments of wood from abroad.
Most dogs are a mix of breeds—in 2015, one study estimated that only 5 percent of dogs in shelters are purebred. Just as dogs come in all sizes, shapes, and colors, these animals also come in a spectrum of temperaments. A bulldog might look fierce but be cuddly as a kitten, whereas a cute cocker spaniel might nip at your finger without thinking twice.