Inbreeding and Linebreeding
Inbreeding is the breeding of one relative to another. This includes any relatives. While all pure breeds will share at some level the same ancestry the biggest factor when considering inbreeding is just how close the ancestors are.
Since biblical times people have inherently known the negative impacts of inbreeding within the human race. For some however they choose to ignore the dangers and feel like some how science and genetics do not hold true when it comes to breeding for pets.
Unfortunately the byproduct of a century of show registries has been the promotion of inbreeding and the subsequent diminished health of all purebred breeds.
While it is true that under certain controlled conditions inbreeding can be used to achieve a more focused and determined outcome or may even be necessary to save a particular species this is more of an exception than the rule. A responsible breeder who chooses to use inbreeding a as tool needs to be highly experienced in the genetics of their breeding stock and understand specifically what their inbreeding intentions are and how they are using inbreeding as a tool to reach that end goal. They must understand if the traits they are looking for are even genetically based or not. Also a responsible breeder must be aware of the potential negative impacts of inbreeding and weigh these against what their desired potential outcome is. If a responsible breeder chooses to inbreed they must also be willing the accept the long-term consequences of their decisions and express the potential long term health risks involved to potential owners. If you consider inbreeding are you willing to be honest to your buyers about potential health issues? Are you willing to pay for the inevitable surgeries such pups will need later in life to fix hip dysplasia or other health conditions? If the answer is no then it is irresponsible to breed in such a way and you should consider a program that promotes greater genetic diversity vs. less.
Unfortunately as is the case most breeders who practice inbreeding do so more for selfish reasons vs. good or well thought out intentions. It is often the case such breeders have kept offspring from past litters or have bought in pairs to save money. Many of these breeders have been misguided and do not understand the true impact of their decisions on inbreeding. It is easy for an inbreeder to even mislead themselves because by all outward appearances their offspring look great. Genetically however in many cases on the inside these offspring are a mess and this only comes to light years down the road when issues like hip dysplasia, mental illness, high rates of cancer and organ failure begin to happen often leaving the owners in a situation of high medical cost and emotional turmoil, especially when euthanasia is the only humane solution.
While the responsible breeder will either be honest about their inbreeding practices and responsible for the outcomes or will look to a non-inbreeding approach many irresponsible breeders on the other hand have intentionally chosen to obscure the issue by changing the terminology from inbreeding to linebreeding. The informed buyer should not be misguided by this redefinition as these are in fact one in the same.
To learn more about the scientific implications of inbreeding please review this article published in the Canadian Veterinary Journal.