Dogs have been companions for humans for centuries. The relationship may be as a true companion or pet, or in a working or service role where the dog is trained or learns to perform tasks to assist its human companions. The working/service role these dogs perform distinguishes them from pedigree dogs who are bred for their conformation and show appearance.

Most dogs are kept as pets and companions. However, throughout the centuries tasks have been performed by dogs which have been used by humans to do a whole variety of helpful jobs.

The following list describes the variety of different tasks and emphasises the versatility of dogs and their ability to perform in certain roles.

 Turnspit dogs were used historically as a source of power; they turned a treadmill connected to a roasting spit or turned a churn to make butter.

 Service or assistance dogs help people with various disabilities in everyday tasks. They include mobility assistance dogs for the physically handicapped, guide dogs for the visually impaired and hearing dogs for the hearing impaired.

 Therapy dogs visit people who are incapacitated or prevented in some way from having freedom of movement; these dogs provide companionship for the elderly in retirement homes, the ill and injured in hospitals or people with particular conditions e.g., autism.

 The training of dogs can also be used as a therapy for human handlers, as is undertaken in prisoner rehabilitation projects.

 Rescue dogs assist people who require assistance such as those in the water after a marine boating accident.

 Search dogs locate people who are missing: lost in the bush or mountains, covered in snow from avalanches or buried under collapsed buildings, for example after earthquakes.

 Working farm dogs are invaluable to sheep and cattle farmers and stockmen around the world for mustering and moving stock around farms and in yards; different breeds are used for the specific jobs involved in stock work. Many of the sheep and cattle dog breeds have been specifically developed for their particular skills. In New Zealand the Huntaway is bred to muster stock and bark to move them on.

 Sled dogs, although primarily used in sporting events, can assist in transporting people and supplies and in medical evacuation in rugged, snowy terrain.

 Performing dogs such as circus dogs and dog actors are trained to perform acts that are not intrinsically useful, but provide entertainment for their live audience or may be an important part of a performance in film and television.

 Hunting dogs assist hunters in finding, tracking, and retrieving game, or they have a role in the control of vermin.

 Guard dogs and watch dogs help to protect private or public property, being either housed within the boundary of a property or used for patrols, as is common in the military and with security firms.

 Tracking dogs help find lost people and animals or track possible criminals for the police forces.

 Cadaver dogs or Human Remains Detection dogs use their scenting ability to discover bodies or human remains at the scenes of disasters, crimes, accidents, or suicides.

 Detection dogs of a wide variety help to detect illegal substances in luggage, or bombs, mines, chemical and other substances. Truffle detecting dogs are used to find the site of truffles in the forest.

 Military Working dogs are used by armed forces for specialized military tasks such as mine detection or communication wire laying. Military Working dogs have been used by armies for centuries but are now highly trained for very specific military tasks.

 Police dogs are usually trained to track or immobilize suspects while assisting officers in making arrests or investigating the scene of a crime and sometimes in crowd control. Some are specially trained for anti-terrorist duties.

 Dogs are sometimes used in programmes to assist children in learning how to read e.g., the Rover program in Washington, USA; there are equivalents in other countries.

This list is long and further tasks and roles for dogs are being added as dogs are trained to detect cancer and be involved in other medical tasks. New research suggests dogs are capable of detecting human patients with melanoma, bowel cancer, mammary cancer and bladder tumours. Chemical substances from some tumours circulate around the body and those substances can be detected by dogs in human body secretions, sweat, urine, faeces or breath. Individual specially trained dogs have provided encouraging and repeatable results in cancer diagnosis. Other medical examples include dogs that can detect a subtle odour that occurs when declining blood sugar occurs in diabetic human patients after insulin administration. These trained dogs alert the owner by barking or whining, licking or giving some other signal which alerts the patient and thus prevents a hypoglycaemic episode. Dogs have also been reported to be able to detect an impending seizure in epileptic patients and provide warning.

The applications for the use of dogs in society are open ended but the use of a dog for a very specific task comes at a large cost for training, care and ongoing support. Dogs that are trained are very valuable and as veterinarians we must recognize the important role we play in their care, welfare and health.

In New Zealand, working dogs are usually heading collies or huntaway dogs trained to work livestock: cattle and sheep. These dogs are not breeds recognised by the Kennel Club but have been developed to perform specific tasks related to particular farming practices. In difficult economic times where labour is expensive, dogs contribute by virtue of their work, a significant service and financial contribution to the farmer, farming community and the country. The general state of health and welfare of all working dogs is important but veterinarians must also be aware of the special diseases or conditions that affect these dogs.

Specific diseases and conditions have been identified by epidemiological studies and prospective research is targeted at the conditions of economic and welfare importance.

In New Zealand we have recognized the importance of service and working dogs. "The Centre for Service and Working Dog Health" established at Massey University has a research focus on diseases of all service and working dogs in New Zealand (http://workingdogs.massey.ac.nz). We recognize the contribution these dogs make to our society now and their increased role in the future. The centre has academic and commercial funding and a financial contribution from donations.

In all WSAVA member countries there will be service and working dogs and breeds which have special health and welfare requirements. Veterinarians must recognize the special needs and care that these dogs demand and be fully prepared to assist and provide that special care. In addition evidence based research is needed to establish an understanding of the important diseases and conditions of these dogs. Finally, the welfare issues of working dogs is paramount and veterinarians have a key role to address welfare issues on behalf of these animals.