The Peril of Pedigree Dogs

We all have a favorite breed of dog. Man's best friend comes in a wide variety of shapes and sizes, many utterly unrecognizable from their wolf ancestors. Whether the huge bundle of fur that disguises the Old English sheepdog or the tiny Chihuahua that's more fashion accessory than pet, there's a dog for everyone. Sadly, though, not all dogs are created equal. For prospective pet owners with strong preferences when it comes to their favored breed, picking a pedigree dog is often considered the best possible choice. You're guaranteed a fine example of everything that typifies your chosen pooch, with the reassurance that they've been produced by a caring, considerate breeder.

Sadly, the reality is much more complex. A pedigree, or purebred, dog is one whose lineage can be traced by its breeders, who, in turn, must be registered with the American Kennel Club. Any puppy produced by a breeder must be guaranteed to conform to a set of guidelines set by the Kennel Club, which mandates specific breed characteristics in order to be identified as a specific breed. These characteristics are maintained through eugenics - controlling which dogs are allowed to breed so that their specific traits are passed to the next generation. It seems fairly simple: pick the best dogs to mate in order to ensure that future puppies are guaranteed to maintain breed standards.

What this method of control produces, however, are severe genetic issues for purebred dogs. By mandating specific dogs that are allowed to mate, breeders are essentially limiting the gene pool for that breed. Evolution depends on a wide gene pool so that a large number of genes can compete with one another to ensure that only the best traits are carried forward to the next generation. Two parent animals of the same species will share similar genetics, but one parent will have a stronger copy of a particular gene than the other. Invariably, it's the stronger gene that will make it to the offspring, giving them a better chance of survival than their parents. By limiting the gene pool of purebred dogs, the chance that the sire (father) and dam (mother) will share the same genetic flaws, passing them on to the pup, is greatly increased.

According to the BBC, a study in 2009 by Imperial College in London discovered that, of the 10,000 pugs in the UK at the time, the genetic traits of those pugs could be traced to just 50 individuals. To quote Steve Jones, professor of genetics at University College London, "People are carrying out breeding which would be, first of all, entirely illegal in humans, and secondly, is absolutely insane from the point of view of the health of the animals."

The Humane Society of America states the worst case - and sadly highly prevalent - scenario, that "the more limited the number of mates, the greater the chance a dog will be bred with a relative who shares similar genes." A BBC investigation into purebred dogs detailed mother-to-son, father-to-daughter and brother-to-sister mating habits - an incestuous practice guaranteed to produce genetic defects in offspring, just as it does in humans.

The American Kennel Club mandates a "breed to improve" standard, which states, "The goal of breeding, after all, is to produce a better dog and a quality pet." However, as Patrick Burns, a columnist who writes for Dogs Today, told the Humane Society of America, as recently as 2010 "in many [American Kennel Club] dogs, the founding gene pool was less than 50 dogs. For some breeds, it was less than 20 dogs."

The results of selective breeding can already be seen in many of the most popular breeds. The humble pug has taken over the Internet as a selfie-loving, clothes-wearing, adorably bug-eyed companion. The only problem? Breeding standards mean that their quality of life is horrendously low. Modern breed standards call for smaller, stockier pugs, with excessive rolls of skin, relatively flat faces and an emphasized curl to the tail. The result of all of this is an animal with numerous health problems.

As pugs have been bred to feature flatter faces and smaller heads, the size of their brain has remained the same. The result? There's simply no room to fit it all - which leads to the bug-eyed appearance of many pugs. Eye prolapse, where the eye pops out of the socket, is common, and can be caused by impact trauma to the head or by simply using a tight leash. Another common problem is with breathing - if you've ever heard a pug snort and splutter as it runs around, don't laugh. The dog is struggling to breathe. Compact airways inhibit the panting effect they use to cool down and an already small nose can be further impacted by pinched nostrils, which limit breathing and may require surgery to stop the pug from passing out due to lack of oxygen.

And pugs are not alone -- far from it. Bulldogs have been bred to feature large heads, which taper to a narrow pelvis. As such, many female bulldogs must give birth by cesarean section, as they cannot pass their puppy's large head through their body. The golden retriever, one of America's most popular dog breeds, is highly susceptible to cancer, hip and elbow dysplasia and several eye diseases. Dog breeds with excess skin, such as shar peis, which were bred to produce more exaggerated wrinkles, require constant maintenance to ensure their skin folds remain infection-free. The Rhodesian ridgeback, so named for the ridge of hair that runs along its back in the opposite direction to the rest of its fur, is susceptible to a skin condition known as dermoid sinus. Healthy puppies born without the ridge, which were less susceptible to the condition, were routinely culled as breeding standards mandated the ridge.

Of course, as breeding standards have changed - in part due to the pressure critics have placed upon kennel clubs and breeding groups - the health of purebred dogs can improve in successive generations. For potential owners, it's important to check the background of any potential breeder you intend to purchase from. Ask for evidence that puppies are not the product of close relatives, and make sure that the breeder isn't producing puppies simply for looks but has made the effort to ensure health is guaranteed above all else. Many purebred dogs don't develop severe health problems and can live long, happy lives with the right care and regular vet visits, but the risk posed by breeding standards makes it much more likely that something will go wrong.

There is a foolproof method to ensure that your dog won't be susceptible to the genetic problems incurred by selective breeding: Buy a mixed breed dog. Mixed breeds, also known as mutts or mongrels, are considered lesser dogs by breeding clubs, but are, in fact, usually healthier and less likely to suffer from long-term health problems and conditions. They're the result of breeding between two dogs of different breeds, and the result is a genetic mix of the two parent dogs. Consider saving the high purchase fee of a pedigree dog and spending a fraction of it at your local kennel or rescue center on a loveable non-pedigree dog. If you need science to justify your purchase to your pedigree-toting friends, The Veterinary Journal published a study that found that mixed breeds live 1.2 years longer on average than pure breeds. Your best friend will be healthier and happier for longer - and that's definitely money well spent.