As the world has evolved, so too has the number of animals in the wild. When animals evolve in nature, this process is known as natural selection and only the strong survive as the best genetic information is passed from one generation to the next. However, there is another method of ensuring that a breed has specific characteristics such as size, coloring, behavior patterns, and so on. This is selective breeding, which is a form of artificial evolution.
While this process follows the same concept as natural selection, man gets involved and forces the changes to occur at a different pace--in some cases the time frame is shorter, in others, it's longer. While selective breeding may result in a "better" dog, it comes with a high risk of many health problems. Here are five common health problems that can occur in dogs which have been selectively bred.
There are several breeds of "pedigree" dogs that are bred specifically for their looks, such as Alaskan Malamutes and German shepherds, that may end up with walking difficulties due to selective breeding. The most of common of these is hip dysplasia, which is caused by an abnormal formation of the hip joints. Others include elbow dysplasia and chondrodystrophia, which occurs when the cartilage grows and matures at a faster than normal rate.
This condition makes the bones fuse together faster than they would normally, resulting in stunted growth, something that is actually sought after in many breeds. But at the same time, it can result in spinal injuries that are extremely painful and may lead to neurological problems.
You might be surprised to learn that selective breeding causes a number of very serious eye diseases. Among these are entropion, corneal trauma/ulceration, and progressive retinal atrophy (PRA).
Entropion is a condition in which the eyelids fold inwards, rubbing the surface of the eye and causing irritation and damage. It is very common in dog breeds with wrinkled faces such as Shar Pei, bulldogs, English mastiffs, and bloodhounds. Corneal trauma and ulceration occur when erosion occurs to the outer surface of the dog's eyes. This is common in dogs with shorter muzzles as their eye sockets are shallower, resulting in bulging eyes that are more prone to injury. PRA covers a range of genetic eye diseases that can cause slow retinal degeneration and a loss of vision that ends in blindness.