Dog harness

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 skijoring, where the dog’s pulling power is utilised, the harness provides effective use of force while maintaining freedom of movement.
History.
Harnesses have been used for millennia to carry weight or pull small carriages or sleds. In both World War I and World War II, service and rescue dogs wore harnesses.
Archeological evidence shows that humans bred dogs for pulling sleds some 10,000 years ago. Artifacts, including rings and parts that connect reins to sleds, have been found on sites throughout the Northernmost stretches of mainland and on arctic islands.
Types of harnesses.
No-pull harness.
No-pull harnesses rely on a level of discomfort, force and avoidance to alter the dogs behavior. When the dog pulls, a strap within the harness tightens. applying pressure on the dog's body which the dog must actively alter the pulling behavior to avoid. If the dog pulls, the leash goes off to the side and directs the dog back towards the owner. That gives a greater ability to control and guide the dog by applying a little pressure.
Sled dog harness.
Harnesses used by sled dogs for running, cycling, sledding, skijoring or pulling weight. 
There are several different types of harness available for sled dogs. Some common harness types: X-back, H-back, half-harness, and spreader bar harness. Spreader bar harnesses are thought to add more power whereas half-harnesses are believed by some mushers to result in fewer athletic injuries. 
A harness with thicker lining and a wider chest strap is preferred for pulling heavy weights. It has been designed to help the dog pull heavy weights efficiently and may feature a spreader bar behind the wheel dogs and in front of the sled or cart. These harnesses help distribute the weight of the cargo over a broader area of the body. 
Rehabilitation and lifting harness.
There are several types of rehabilitation or dog lifting harnesses depending on which parts of the dog’s body needs help. It is a harness with at least one handle that wraps around a dog's body to allow a person to help lift the weight off of their hips, spine or legs. 
There are several different types of them available, each of them providing their own unique advantages. They include: front harnesses, rear harnesses, front and rear combo, mid-section support harnesses, amputee harnesses and full body harnesses. There are several conditions that may make it necessary or at least helpful to use a dog lifting harness, some of the most common being: hip dysplasia, broken bones, sprained knees, spine injuries, arthritis, recent surgery, strained muscles and missing limbs. 
Tactical dog harness.
A tactical dog vest or harness provides an extra layer of protection that is needed. Most tactical dog vests are provided with a handle to help the dog on difficult terrain. It can also be used to hold additional devices, such as a GPS tracker or a light. Further specialization is possible depending on needs: bulletproof; suitable for descent; mantrailing harness, etc. 
Assistance dog harness.
Assistance dogs (https://en.wikipedia.org/wiki/Assistance_dog) usually have a vest, cape or harness for identification. The gear is often utilized during the dog’s work. Cape harnesses are ergonomic and well-made. Usually there is ample space for identification patches. The pulling harnesses are worn by service dogs who need to pull heavy weight. Pulling harnesses are usually padded for comfort. Mobility support harnesses are for assistance dogs who need to pull their owners. They are ergonomic and have a rigid handle. 
Car safety harnesses.
Safety harnesses were designed to restrain the animal in a car seat using the car's seat belt. In the event of an accident the harness distributes the pulling force. Several car safety harness have been designed that pass crash tests conducted in the USA by the Center for Pet Safety.