Selective breeding is defined as the intentional breeding of organisims with desirable traits in an attempt to produce offsprings with similar desirable characteristics or with improved traits (Biology Online, 2013, http://www.biology-online.org/dictionary/Selective_Breeding)
Selective Breeding in Pedigree DogsEdit
Humans have placed a very strong selective pressure on dogs. It is believed that in the early days of domestication, dogs would have been selected for traits that were useful to humans such as tameness and hunting behaviors that would have helped humans attain food (McGreevy & Nicholas, 1998). During the Medieval and Renaissance periods, there was an increase in creation of dog breeds that were highly functional for specific purposes such as herding, guarding and hunting (Galibert et al., 2011). Today, a greater emphasis on the appearance of dogs has become popular with the rise of dogs shows and organizations like the Kennel Club and American Kennel Club (McGreevy & Nicholas, 1998). Today's dogs have come a long way since their early ancestors followed and stayed with man during the agricultural revolution. Through selective breeding, the dog's traits have been changed, and continue to be altered today.
True Cost of a PedigreeEdit
Unsafe breeding practices are still prevalent in the purebred dog world and it is a sad truth that 25% of the 20 million purebred dogs in America are afflicted with a serious genetic problem (Lemonick, 2001). In England, the British Veterinary Association/Kennel Club has been tracking the spread of hip dysplasia since 1984. In 2006, they found that hip dysplasia were common in 21% of the breeds they tested which include the Pug, Beagle, Corgi, Bulldog, Border Collie, Great Dane, Standard Poodle, German Shepard and Golden Retriever, just to name a few. In fact, one study found that 24.6% of the Rottwielers in their research group had hip dysplasia (Advocate for Animals, 2006). The BVA/KC also found that elbow dysplasia is common in Bassett Hounds, Irish Wolfhounds and one study found that 17.8% of Labrador Retrievers had this genetic disease (Advocate for Animals, 2006). According to the Advocate for Animals (2006), up to one third of purebred dogs are affected by inherited eye or eyelid conditions such as cataract, glaucoma and degeneration of the retina. For example, Lemonick (2011) found that at least 70% of Collies suffer from genetic eye conditions, and 10% will eventually go blind. Some dog breeds have also been shown to have a higher risk for heart conditions than the rest of the dog population. One study found that 6.5 per thousand purebred dogs suffer from dilated cardiomyopathy. The study found that purebreds are four times more likely than mixed breeds to suffer from this condition (Advocate for Animals, 2006). The genetic problems listed here are just a small summary of the many problems faced by pedigreed dogs today.
Galibert, F., Quignon, P., Hitte, C., & Andre, C. (n.d). Toward understanding dog evolutionary and domestication history. Comptes Rendus Biologies, 334(3), 190-196
Lemonick, M. (2001). A Terrible Beauty. TIME Magazine. Retrieved from: http://content.time.com/time/magazine/article/0,9171,163404,00.html
McGreevy, P. D., & Nicholas, F. W. (1999). Some practical solutions to welfare problems in dog breeding. ANIMAL WELFARE-POTTERS BAR-, 8, 329-342.