Sled dog in the context of "Park ranger"

The dog (Canis familiaris or Canis lupus familiaris) is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. Dogs were the first species to be domesticated over 14,000 years ago, before the development of agriculture. Due to their long association with humans, dogs have gained the ability to thrive on a starch-rich diet that would be inadequate for other canids.

Dogs have been bred for desired behaviors, sensory capabilities, and physical attributes. Dog breeds vary widely in shape, size, and color. They have the same number of bones (with the exception of the tail), powerful jaws that house around 42 teeth, and well-developed senses of smell, hearing, and sight. Compared to humans, dogs possess a superior sense of smell and hearing, but inferior visual acuity. Dogs perform many roles for humans, such as hunting, herding, pulling loads, protection, companionship, therapy, aiding disabled people, and assisting police and the military.

A dog sled or dog sleigh is a sled pulled by one or more sled dogs used to travel over ice and through snow, a practice known as mushing. Numerous types of sleds are used, depending on their function. They can be used for dog sled racing. Traditionally in Greenland and the eastern Canadian Arctic the Inuit had the dogs pull in a fan shape in front of the sled, while in other regions, such as Alaska and the western part of Northern Canada the dogs pull side by side in pairs.

Sled dog racing (sometimes termed dog sled racing) is a winter dog sport most popular in the Arctic regions of the United States, Canada, Russia, Greenland and some European countries. It involves the timed competition of teams of sled dogs that pull a sled with the dog driver or musher standing on the runners. The team completing the marked course in the least time is judged the winner.

Sled dogs, known also as sleighman dogs, sledge dogs, or sleddogs, are a highly trained dog type that are used to pull a dog sled, a wheel-less vehicle on runners, over snow or ice, by means of harnesses and lines.

A toboggan is a simple sled used in snowy winter recreation. It is also a traditional form of cargo transport used by the Innu, Cree and Ojibwe of North America, sometimes part of a dog train.

It is used on snow to carry one or more people (often children) down a hill or other slope for recreation, or as a rescue sled. Designs vary from simple, traditional models to modern engineered composites. A toboggan differs from most sleds or sleighs in that it has no runners or skis (or only low ones) on the underside. The bottom of a toboggan rides directly on the snow. Some parks include designated toboggan hills where ordinary sleds are not allowed and which may include toboggan runs similar to bobsleigh courses.

The 1925 serum run to Nome, also known as the Great Race of Mercy and The Serum Run, was a transport of diphtheria antitoxin by dog sled relay across the US territory of Alaska by 20 mushers and about 150 sled dogs across 674 miles (1,085 km) in 5½ days, saving the small town of Nome and the surrounding communities from a developing epidemic of diphtheria.

Both the mushers and their dogs were portrayed as heroes in the newly popular medium of radio and received headline coverage in newspapers across the United States. Balto, the lead sled dog on the final stretch into Nome, became the most famous canine celebrity of the era after Rin Tin Tin, and his statue is a popular tourist attraction in both New York City's Central Park and downtown Anchorage, Alaska. Togo's team covered much of the most dangerous parts of the route and ran the farthest: Togo's team covered 261 miles (420 km) while Balto's team ran 55 miles (89 km).

Dog types are broad categories of domestic dogs based on form, function, style of work, lineage, or appearance. Some may be locally adapted dog types (or landraces) that may have the visual characteristics of a modern purebred dog. In contrast, modern dog breeds strictly adhere to long-established breed standards, that began with documented foundation breeding stock sharing a common set of inheritable characteristics, developed by long-established, reputable kennel clubs that recognize the dog as a purebred.

A "dog type" can be referred to broadly, as in gun dog, or more specifically, as in spaniel. Dogs raised and trained for a specific working ability rather than appearance may not closely resemble other dogs doing the same work, or any of the dogs of the analogous breed group of purebred dogs.

A dog harness is a piece of equipment consisting in part of straps that surround the dog’s torso. It is used to guide, hold, and lift the dog or to utilise its pulling power. It reduces tension on the neck when they pull, and provides free breathing during daily walks. In sports such as mushing and skijoring, where the dog's pulling power is utilized, the harness provides effective use of force while maintaining freedom of movement. These aforementioned kinds of harnesses differ from pet harnesses in that they are specifically designed in order to allow or support a dog in the completion of a working task.