The average pet owner is not a dog handler. A dog handler is a person who works with highly trained dogs under special conditions. Some dog handlers are professionals, but many are amateurs. Some train the dog they work with, while others are educated to handle a dog that is already trained.

A show dog handler is a professional who presents dogs for judging at dog shows, where they are evaluated for physical traits. Usually a show dog handler also trains and grooms the dog he shows, and often the clients' dogs live in his kennels while they are being shown. In many countries, a professional dog handlers' organization works with the national kennel club to establish and maintain standards.

Military dogs serve in four main areas: narcotics detection, explosive detection, specialized searches, and combat tracking. They also work as sentries, messengers, and scouts. Each dog is paired with a dog handler who is trained to work with the dog. Experienced military dog handlers can go on to become trainers of both dogs and new handlers. Today, military dogs and handlers also work with homeland security.

A search and rescue dog handler is usually a volunteer who has trained his own dog in special search techniques. SAR dogs are trained in tracking, site searches, and cadaver discovery. A SAR dog handler must be educated in advanced first aid and rescue procedures.

Assistance dogs help people with handicaps, and they are trained by professional dog handlers. Usually an assistance dog handler specializes in one or two kinds of training. Guide dogs for the blind are a well-known type of assistance dog, but other specializations include hearing assistance, seizure prediction, and general assistance. Assistance dogs usually wear identification when they work in public, and they are allowed in areas that are off limits to pets.

A stock dog handler works with a dog or team of dogs to herd and manage other animals. Sheep dogs are the most common, but stock dogs also herd cattle and other animals, and sometimes even geese or ducks. Usually a stock dog handler is also the owner of the herding dog. Today, herding is also a sport, and many handlers and dogs compete at trials.

A therapy dog handler is usually a volunteer who takes his dog to visit the elderly, the sick and injured, or others who need a little canine companionship. Both the dog and the dog handler are trained and certified for the job. In addition, therapy dogs must be in excellent health.