Originally, working terriers were bred to hunt foxes, badgers and rats in England. Although many of these dogs have now become loyal, family companions or watch dogs, some are still bred as working dogs.
As a watchdog, a terrier needs to be involved in a good training program to perform that job correctly. Randomly attacking strangers can result in problems that are greater than the ones they were intended to solve. Representing a barrier to trespassers is good, but preventing a workman to come into the house is not.
American Pit Bull Terriers are frequently discovered among professional working dogs. They're employed by the Border Patrol, DEA and other government security establishments. They are extremely strong working terriers, have great endurance and can track well when trained properly.
For many of the same reasons, they're often utilised by the police to sniff out drugs or explosives. But even people needing dogs for more domestic services, the working terrier can often be a very useful dog.
They can be bred to chase small game, and can perform well as a rat catcher. Cairns, Jack Russells and others will do this instinctively. The main problem is to get them to stop before they've dug up the entire yard. Here again, without proper training, the result can be worse than the problem.
Farmers often utilise working terriers to control grey foxes, raccoons, ground hogs and other pests that prey on chickens and other fowl. Jack Russells, Fox Terriers and other smaller terrier breeds are used for this purpose. An important factor is the chest circumference should be no larger than the animals they chase in order to allow the dog to get inside the animal's burrows
The terrier is still used as a hunting dog. They're not by nature retrievers, but they can locate and alert, and they can easily trap small game, such as rabbits and foxes.
Many terriers are high-energy dogs, but that instinct can be put to good purpose. These breeds are too small to serve as guide dogs for the blind, but some make very good service dogs for the deaf. With their intelligence and keen attention to the right stimulants, they could alert someone to a ringing phone, a visitor at the door, or somebody trespassing on their property.