As a food source

Dog meat is consumed in some East Asian countries, including Korea, China, and Vietnam, a practice that dates back to antiquity. It is estimated that 13–16 million dogs are killed and consumed in Asia every year. The BBC claims that, in 1999, more than 6,000 restaurants served soups made from dog meat in South Korea. In Korea, the primary dog breed raised for meat, the nureongi (누렁이), differs from those breeds raised for pets which Koreans may keep in their homes. The most popular Korean dog dish is gaejang-guk (also called bosintang), a spicy stew meant to balance the body's heat during the summer months; followers of the custom claim this is done to ensure good health by balancing one's gi, or vital energy of the body. A 19th century version of gaejang-guk explains that the dish is prepared by boiling dog meat with scallions and chili powder. Variations of the dish contain chicken and bamboo shoots. While the dishes are still popular in Korea with a segment of the population, dog is not as widely consumed as beef, chicken, and pork.
Other cultures, such as Polynesia and Pre-Columbian Mexico, also consumed dog meat in their history. However, Western, South Asian, African, and Middle Eastern cultures generally regard consumption of dog meat as taboo. In some places, however, such as in rural areas of Poland, dog fat is believed to have medicinal properties—being good for the lungs for instance.

Info from: http://en.wikipedia.org/wiki/Dog