Selective breeding for specific features in dogs may help them win at dog shows or help their owners gain admiration from their neighbors, but the practice has led to serious health problems among some breeds that veterinarians warn can cause these dogs a “lifetime of suffering”.
Why is over-breeding risky? According to researchers from the Royal Veterinary College, the act of selective breeding causes a lack of genetic diversity within dog breeds. This lack of genetic diversity can increase the risk of inherited diseases like cancer and blindness.
Here are just a few examples of how repeated inbreeding has led to health problems:
Pugs: While many breeds have changed dramatically over the years due to selective breeding (the flat faces, curly tails and big eyes of pugs, for instance, did not evolve naturally, and are the result of selective breeding) in a study this week, vets warned that pugs are up to 54x more likely to suffer adverse health conditions–this includes brachycephalic obstructive airway syndrome, corneal ulceration and skin fold dermatitis. Additionally, pugs are 2.5 times more likely to suffer from obesity, and twice as likely to have overgrown nails. Pugs also have a very short life expectancy of just 7.4 years – considerably shorter than the average life expectancy across all breeds, of 11.2 years.
The extreme characteristics many owners find so appealing, such as squashed faces, big eyes and curly tails, are seriously compromising pugs’ health and welfare and often result in a lifetime of suffering… While these extreme, unhealthy characteristics remain, we will continue to strongly recommend potential owners do not buy brachycephalic breeds such as pugs.
–Dr. Justine Shotton, British Veterinary Association (BVA) President
Boxers: Boxers have been bred to have shorter faces with a larger mouth, while dachshunds’ backs and necks have stretched out and Boxers’ legs have shrunk to a point that makes it difficult for them to maneuver over obstacles just a few inches off of the ground. Additionally, Boxers are successors of the extinct bullenbaiser breeds, which was a cross of mastiff, bulldog and, some suggest, a Great Dane and terrier. Developed in 19th century Germany, these dogs were designed as bull baiting dogs and later as butcher’s helpers, controlling the cattle in slaughterhouses. Before being turned into working dogs, the boxer had a longer face and longer downward tail. Today’s Boxer has a shorter face with a larger mouth that slightly points upwards, which has been known to host numerous health problems. Among the common health conditions of today’s Boxers are being prone to contract cancer, cardiomyopathy, heart disease, kidney disease, hip dysplasia, hypothyroidism, diabetes, degenerative myelopathy, among other serious health conditions.
Bull Terrier: The Bull Terrier was first created in the early 1800s with the mix of the old English Terrier and the Bulldog. During this time, dog fighting was a big source of entertainment in Europe and people were always trying to breed dogs into better fighters. Prior to being a stocky fighter, Bull Terriers had a slim curved body and a more chiseled nose. Over the years, the animals mutated to have a warped skull and thicker abdomen, and Bull Terriers also gained a compulsive tail-chasing trait. Today’s Bull Terriers are also prone to kidney disease, heart disease, skin problems and deafness.
Basset Hound: The Basset Hound’s short, curved legs are a result of an extra copy of a specific gene, which produces growth protein. Prior to human interruption, this dog had shorter ears, a less droopy face and a curve in its back. Today, their bellies are much lower to the ground and their rear legs have also seemed to lower with excessive skin and larger floppy ears. Basset Hounds are prone to vertebra problem and droopy eyes that are constantly suffering from entropion and ectropion.
Dachshunds: The Dachshund once had more functioning legs and a neck more in proportion to its size. But thanks to humans, their backs and necks have stretched out and their legs have shrunk to a point that makes it difficult for them to maneuver over obstacles a few inches off of the ground. Dachshunds: are known to have the highest risk of any breed for intervertebral disc disease which can result in paralysis. They are also prone to achondroplastic related pathologies, PRA – an inherited eye condition – and problems with their legs.
German Shepherd: The German Shepherd is also a result of too much breeding that ruined a canine species. First attempts to standardize this breed began in the 1850s, with the goal of preserving traits that helped the dogs with their job of sheep herding. They improved the dog’s intelligence, speed, strength and keen sense of smell, which resulted in dogs of the same breed that differed from each other. The over-bred German Shepherd is at an increased risk for painful elbow and hip dysplasia, degenerative disk disease, dental problems including gum disease, cancer, nose infections, urinary tract infections, diabetes and perianal fistula, among other health issues.
Journal Reference: O’Neill, D.G., Sahota, J., Brodbelt, D.C. et al. Health of Pug dogs in the UK: disorder predispositions and protections. Canine Med Genet 9, 4 (2022). https://doi.org/10.1186/s40575-022-00117-6