The Lurcher is not a dog breed, but rather a type of dog. It is a hardy crossbred sighthound that is generally a cross between a sighthound and a working breed, usually a pastoral dog or Terrier. Collie crosses have always been very popular. Lurchers can be crossed several times. There is no set type, so they can be as small as a Whippet or as large as a Deerhound; but most are chosen for a size similar to that of a Greyhound, and a distinct sighthound form is preferred.

These dogs specialize in pursuing prey, keeping it in sight, and overpowering it by their great speed and agility. They must be able to quickly detect motion, so they have keen vision. Sighthounds must be able to capture fast, agile prey such as deer and hare, so they have a very flexible back and long legs for a long stride, a deep chest to support an unusually (compared to other dogs) large heart, very efficient lungs for both anaerobic and aerobic sprints, and a lean, wiry body to keep their weight at a minimum.

The typical sighthound also has a light, lean head, which is referred to as being dolichocephalic in its proportions. This shape can create the illusion that their heads are longer than usual. Dolichocephaly is actually a characteristic of wolves and other wild carnivores, and is related to the need for stereoscopic vision in active hunting. For reasons not yet understood, most domesticated animals including dogs (other than the sighthounds) have become brachycephalic—short-headed—and have partially lost this aspect of their field of vision