Man’s best friend comes in different shapes, sizes, and colors. You want a large dog with a beautiful coat; you can have that in a golden retriever. What about a dog who has a fierce bark to ward of intruders? A German Shepherd does the trick. Do you want a dog that can survive in the coldest climate and still function normally? A Siberian husky will do.
All this variety comes not necessarily due to natural selection- man has a hand in it through a process called selective breeding. The process has the advantage of creating dogs that look exactly as the breeders intend, but come with a variety of inherited disorders as listed below.
The flattened face of a pug or causes breathing problems because they have a shorter nasal cavity than their ancestors. The scientific name for this disorder is brachycephalic airway obstruction syndrome. The nasal cavity of these dogs is intentionally shortened to match the breed standard.
Some dogs have difficulties giving birth because the breed standard dictates they should have a large head, broad shoulders, and a narrow pelvis. These characteristics mean the puppies have a large head, but the mother has a narrow pelvis so she is not able to give birth normally. The bulldog is one breed that has this problem, and almost always has to be assisted in giving birth via a caesarian section. The females also have to be artificially inseminated because their backs can’t hold the weight of a male.
Small dogs such as Chihuahuas and Cavalier King Charles Spaniels are bred to look cuddly and doll-like. As breeders strive to make these breeds more doll-like, they create a disorder known as Chiari Malformation. This disorder causes certain parts of the brain to push through the base of the skull when certain skull bones fuse too soon. The effects are painful headaches due to too much pressure on the brain. They also have difficulty walking and can get paralyzed.
Large dogs such as Labradors, Great Danes and Rottweilers are heavy, causing a lot of pressure on their bones. This leads to higher incidence of bone cancer among these dogs. Hip dysplasia, the abnormal formation of the hip joint is also common among large breeds such as German Shepherds.
These are just some of the problems caused by selective breeding in dogs. Personally I like the physical traits and temperaments of my purebred dogs, and I wouldn’t trade these for anything. The predictability of purebred dogs makes it easy to choose a dog that fits into your home, but the problems caused by selective breeding are a pain. In my opinion, the best way forward is not to do away with the dogs, but to encourage responsible breeding that eliminates the problems. Breeders should put the health of the dogs first before the looks.