Hound Group. The Hound Group is divided into two subgroups, the Sight Hounds and Scent Hounds. Scent hounds use their superior sense of smell to trail their quarry, barking as they go. This lets their hunter-partner know where the dogs are so he can arrive and dispatch the prey. The Beagle, and the legendary tracker, the Bloodhound, are both scent hounds. Scent hounds have the typical hound 'bay', which if used excessively, can become annoying. Scent hounds may be more interested in routing through the garbage or freshly-fertilized flower beds than other breeds. Sighthounds, sometimes called 'gazehounds', use their superior eyesight to locate prey up to half a mile away. Then, with their incredible speed, they typically chase down and kill their quarry unassisted. Sighthounds are sensitive to chemicals, including anesthesia and sulfa drugs. They tend to startle easily if they are touched unexpectedly. These dogs have a very strong instinct to chase anything that flees from them, and as a pet, they may become timid. Perhaps most surprisingly, however, most Sight Hounds do not require a great deal of exercise, because they are built for a sprint, not a marathon. Perhaps the best-known sighthound is the Greyhound. All hounds were developed to hunt with little or no help, resulting in breeds that are independent. Because of this, hounds tend to be difficult to train, having earned the reputation of being stubborn. In most cases, they simply prefer to pay more attention to what they smell or what they see going on around them than to a trainer. Although most hounds are active dogs, they do not require the exercise needed by breeds in the Sporting group or that many of the Herding breeds need. However, they do need secure fences to keep their hunting instincts from leading them astray. Working Group. The Working Group contains breeds created to pull loads, guard livestock and homesteads, and assist fishermen. Some Working Group dogs still serve in their traditional roles, but today's working dogs also perform a diverse range of tasks never envisioned by their original breeders. Some, such as the German Shepherd, serve as guide dogs or assistance animals for the physically challenged. Others engage in police work, and are integral members of search-and-rescue teams. Except for the Nordic or sled dogs, which some people think should be a separate group, most Working dogs are large or very large but need far less exercise than their size may indicate. However, the Boxer, Standard Schnauzer, and Portuguese Water Dog all need a healthy dose of exercise to keep them happy. Sled dogs are more social than their much larger Working Dog comrades. Born to pull loads over vast distances, they have little sense of territory and no sense of home. Beware; a loose sled dog is a lost sled dog. Terrier Group. The Terrier Group contains dogs ranging in size from small to large. Terriers, bred to hunt vermin from the size of a mouse to the size of a fox or badger, love to dig. Because of their independence and feisty attitude, most do not make a good choice for a first-time owner, for people with other dogs or families with young children. Even the smallest terriers are fearless dogs that, because of their small size, sometimes need rescued from situations they create. A small terrier is truly a big dog in a small dog's body.