The Bluebonnet Norfolk Terrier Club does not recommend, guarantee, endorse, nor rate these recommendations or contributors, their kennel or their stock. The purpose of this section is to share the knowledge and experience of breeders who have vast experience in whelping and raising puppies. The tips and tricks below are intended to augment qualified veterinarian care, not as a substitute for qualified veterinarian care of the dam and puppies.
From Good Dog, Bad Gene: Sue Pearce-Kelling, president of Optigen, says that breeders are often dismayed to the point of overreacting when a disease is identified in their breed. Advice from breed clubs having experienced this is reassuring. "Once it becomes clear that the DNA test will allow them to continue to breed any of their dogs and still be assured of avoiding disease, they realize they can retain the good qualities and gradually move away from the disease over time," says Pearce-Kelling. "If they want to breed a dog that carries a recessive mutation, they simply need to choose a mate that does not carry that mutation, and then choose 'clear' offspring from that generation or a following one."
PEDIGREE ANALYSISGeneticists' and breeders' definitions of inbreeding vary. A geneticist views inbreeding as a measurable number that goes up whenever there is a common ancestor between the sire's and dam's sides of the pedigree; a breeder considers inbreeding to be close inbreeding, such as father-to-daughter or brother-to-sister matings. A common ancestor, even in the eighth generation, will increase the measurable amount of inbreeding in the pedigree.The Inbreeding Coefficient (or Wright's coefficient) is an estimate of the percentage of all the variable gene pairs that are homozygous due to inheritance from common ancestors. It is also the average chance that any single gene pair is homozygous due to inheritance from a common ancestor. In order to determine whether a particular mating is an outbreeding or inbreeding relative to your breed, you must determine the breed's average inbreeding coefficient. For the calculated inbreeding coefficient of a pedigree to be accurate, it must be based on several generations. Inbreeding in the fifth and later generations (background inbreeding) often has a profound effect on the genetic makeup of the offspring represented by the pedigree.