Selective breeding animals has been happening for a very long time. Humans have done it with multiple species, but there is growing back lash towards selective breeding when it comes to pets, dogs especially.
Selective breeding of dogs was started in order to bring out favorable characteristics and to breed out undesirable ones. The problem with this is that the humans who started this did not have any regard for how the changes to these animals would affect their long-term and short-term heath as an individual animal and as a breed as a whole.
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Today, more and more emphasis is being put on non selective breeding and not promoting the breeding of pure breeds. The Science and Dogs blog put together a side-by-side comparison of several popular dog breeds from the 1915 book Dogs of All Nations by Walter Esplin Mason showing what they look like today.
The photos below show how dogs have changed, and the effect that selective breeding can have on animals in just 100 years.
Pugs: One of the most desirable (and adorable) traits about a modern pug is its double curled tail. This is actually a genetic defect, and if severe enough it can actually lead to paralysis. Pugs did not originally have this double curve tail. They also have a host of breathing and respiratory problems.
Basset Hounds: The Basset Hound was selectively bred so much that it caused a shortening of the hind legs, the longer droopy ears and droopy eyes that are prone to certain eye conditions in dogs such as entropion and ectropion. The Basset Hound also now has an excessive amount of skin for its body.
German Shepherds: German Shepherds were originally medium-sized dogs with no slope to their back. Now they have shorter hind legs and are about 30 pounds heavier than what they used to be. There used to be a time when a German Shepherd could jump over a 8.5 foot wall.
English Bulldogs: If any breed has come to signify what can go wrong with selective breeding, it is the English Bulldog. Pretty much every health problem you can think of in a dog, they are plagued by. The median age for an English Bulldog is 6.25 years according to a 2004 study by the Kennel Club. Their sheer mass alone makes mating and birthing almost impossible without medical intervention.
Dachshunds: Dachshunds bodies have been elongated which gives them the highest odds of any dog to develop intervertebral disc disease. Their legs have been shortened so much that there is barely any clearance between them and the ground anymore.
Bull Terriers: Bull Terriers have changed dramatically in 100 years. Selective breeding has caused them to have teeth problems, skin allergies as well as compulsive tail-chasing. Not to mention the deformed skull.
Doberman Pinscher: Doberman’s are very prone to something called Cardiomyopathy which is an enlarged heart. Another condition that is the result of selective breeding is cervical vertebral instability. This is caused by a malformation of one of the vertebrae in the neck which can lead to excessive pressure on the spinal cord. This can cause weakness in the back and lack of coordination in the hind quarters.
Saint Bernard: Originally bred as working dog, you won’t find many of these dogs doing that anymore. Overheating is a major concern for these very large animals and their workload must be closely monitored. Their large size also makes them more prone to hip and elbow dysplasia. Cardiomyopathy is also something Saint Bernard owners need to be aware of, as well as certain kinds of cancer such as Osteosarcoma.
Boxers: The flattening of a dogs muzzle is almost never a good thing. In Boxers and many other breeds this can lead to breathing and respiratory problems. Boxers also face problems with a specific Cardiomyopathy that only Boxers can get that is usually fatal.
Salukis: Salukis are prone to eye problem such as progressive retinal atrophy, corneal dystrophy and glaucoma. They can also be susceptible to vonWillebrands disease, which is a blood clotting disorder as well as hypothyroidism. As far as physical appearance goes the Saluki has not changed much however.
Bearded Collies: Bearded Collies many of the times will suffer from hip and elbow dysplasia. They can also develop eye problem and autoimmune thyroiditis. Selective breeding has made their coat absolutely huge as well.
White Terriers: These dogs can be prone to many health problems like atopic dermatitis, luxating patellae (knee caps that pop out of normal position), aggression, Legg-Calvé-Perthes disease (a disease involving the hip-joint), dry eye, Addison’s disease and a host of other ailments. Physically you can see a change in the head and ears. Also the legs are much harrier and see a little shorter.
Rottweilers: Modern Rottweilers are black in color with well-defined reddish-brown spots on the face, cheeks, under the eyes, on the lower part of the chest, and on the legs. The fur is coarser now, and they don’t have their tails docked anymore.
Irish Setter: This breed hasn’t changed much in over 150 years (the black-and-white picture was taken in 1879). Irish Setters have only become a bit thinner and lighter, and they have longer and thicker fur now.
Airedale Terrier: This breed almost hasn’t changed except for becoming ‘shaggier’ and longer in the face.
Many of these dogs were perfectly healthy breeds before humans started interfering with and manipulation their genetics. All for a physical characteristic that some rich person wanted more pronounced in their dog. It can be really sickening when you think about it a little bit. Dogs have died because people were so arrogant that we felt it was better to have a dog with a little more hair on its head and kill some to get it done than to just leave the breed alone and appreciate dogs for what they are. Mans best friend.
H/T dogbehaviorscience.wordpress