Gou Gu

Gou Gu is not a plant but the dried bone of the domestic dog, Canis lupus familiaris Linnaeus (family Canidae). The medicinal substance traditionally consists of the long bones of the limbs, the cranium, or the mandible of slaughtered animals, defleshed, boiled to remove residual soft tissue and marrow, sun-dried, and either used whole, broken into pieces, or calcined to a friable white ash before pulverising. Specimens are creamy-white to pale grey externally, hard, and odourless when properly cleaned. Its composition is the typical calcium-phosphate mineral matrix of vertebrate bone (predominantly hydroxyapatite) with residual organic collagen. The substance is a minor and largely historical entry in the Chinese materia medica.