Inbreeding means breeding closely related animals. Linebreeding is a form of inbreeding.

Pedigree (purebred) dog breeders tend to define inbreeding as breeding first-degree relatives: for example, mother to son, father to daughter. They define linebreeding as mating second-degree relatives, for example grandfather to granddaughter, first cousins, or more distant relatives that share a common ancestor.

Inbreeding and linebreeding both significantly increase the chance that the offspring will suffer from an inherited disorder. The only difference is in the level of risk: the more closely related the parents, the greater the chance of producing offspring with inherited disorders.