Introduction
The English Bulldog is a popular breed with a distinct appearance characterized by a short, stocky build with wrinkles on the face and wide, muscular shoulders. According to the American Kennel Club (AKC), bulldogs trace their ancestry back to the ancient Greeks and Phoenicians. They were originally bred for the bloody sport of bull baiting in England beginning in the 1200s. After bull baiting was banned in 1835, the bulldog nearly went extinct. However, some enthusiasts kept breeding them, and the dogs were later crossed with terriers to create a smaller, friendlier, and more energetic breed. Eventually, the bulldog was reinvented as a companion animal known for its friendly temperament.
Today, the English Bulldog remains a beloved breed and symbol of England and British culture. However, years of selective breeding have taken a toll on the breed’s health and genetic diversity. The extremely pushed in face, heavy body, and other exaggerated physical features have resulted in numerous health problems. With low genetic diversity, the breed is also prone to additional issues. There are concerns about the long-term viability of English Bulldogs due to these factors.
English Bulldog Breed Standards
The English bulldog breed has specific standards that have been established by major kennel clubs like the American Kennel Club (AKC) and the United Kennel Club (UKC). These standards outline the ideal physical and temperamental characteristics for the breed.
According to the AKC breed standard, English bulldogs should exhibit strength, stability and vigor. They should have a short, broad head with a short muzzle, broad shoulders and a thick, strong body. Their coat should be straight, short and lying flat. Acceptable colors include red, fawn, white, brindle and piebald. Temperamentally, they should be docile, courageous and friendly.
The UKC English Bulldog breed standard also specifies a sturdy, compact build with heavy bone structure and a smooth, short coat. Desired traits include an affectionate, loyal and courageous temperament. Faults include nervousness, hostility towards other dogs, and excessively timid behavior.
Overall, the standards emphasize a powerful, sturdy physique along with a friendly, gentle disposition for the English bulldog. Breeders aim to produce dogs that conform as closely as possible to these established ideals.
Genetic Diversity
Genetic diversity refers to the range of different genes and alleles found within a population. It is a measure of the genetic variation that occurs naturally within a species. Genetic diversity arises through mutations and recombination and allows a species to adapt to changing environments. It is the basis for selective breeding programs used to improve crops and livestock.
According to the University System of Maryland, genetic diversity is defined as “the range of different inherited traits within a species.” These traits are determined by an individual’s genetic code, or genotype, which contains DNA inherited from both parents. Genetic diversity results from mutations that occur during DNA replication and recombination between homologous chromosomes during meiosis. This leads to differences in base sequences and alleles, creating variation among individuals.
As defined by Wikipedia, genetic diversity is “the total number of genetic characteristics in the genetic makeup of a species.” It encompasses diversity within and among populations of a single species as well as diversity among different species. Greater genetic diversity correlates with the health and long-term survival of a population or species.
In summary, genetic diversity refers to all the genetic differences within a species. It provides the genetic variation that allows populations to adapt and species to evolve in response to environmental changes.
Current Genetic Diversity of English Bulldogs
Several studies have assessed the genetic diversity within the English Bulldog breed and found it to be quite low compared to other breeds. A 2016 study by UC Davis analyzed DNA from 102 registered English Bulldogs and found that the breed has very low genetic diversity, likely resulting from a small founding population and breeding practices that further reduce diversity (https://www.ucdavis.edu/news/bulldog-genetics).
Another 2016 study analyzing DNA from 170 English Bulldogs concluded the breed has extremely low genetic diversity, with a small effective population size resulting from a limited number of ancestors (https://pubmed.ncbi.nlm.nih.gov/27478618/). The researchers suggested opening the stud book and increasing genetic diversity by outcrossing may be necessary to ensure the breed’s health and viability.
Overall, multiple genetic analyses consistently show English Bulldogs have far less genetic diversity than most other breeds. This lack of diversity can be attributed primarily to a small founding population and breeding practices that prioritize certain physical traits over health and function.
Health Issues Related to Low Genetic Diversity
The English bulldog is prone to many health issues due to decades of inbreeding and a shrinking gene pool. Some common health problems in the breed include:
- Breathing problems – English bulldogs commonly suffer from brachycephalic airway syndrome due to their pushed-in faces and narrow nostrils. This can lead to difficulty breathing, overheating, and exercise intolerance.
- Skin conditions – Skin folds around the face, combined with allergies, can result in chronic skin infections and irritation.
- Joint and skeletal problems – Hip and elbow dysplasia are common due to the bulldog’s stocky body shape and breeding focused on specific physical features.
- Eye issues – Entropion, an inward rolling of eyelids, causes irritation and infections. Cherry eye, a prolapsed third eyelid gland, is also frequently seen.
- Cancer – Lymphosarcoma, mast cell tumors, and bone cancer occur at higher than average rates.
- Dental disease – Crowded, misaligned teeth that do not properly meet often result in early tooth loss and dental infections.
- Heart disease – English bulldogs are prone to a variety of heart conditions including pulmonic stenosis, mitral valve disease, and cardiomyopathy.
The limited gene pool has concentrated genetic mutations and physical exaggerations that negatively impact health. Outcrossing to increase genetic diversity could help improve overall health and viability of the breed.
Breeding Practices
Current breeding practices for English Bulldogs have resulted in generations of dogs with limited genetic diversity. Breeders have historically selected for specific physical traits in line with breed standards without considering the impact on genetic health (wikiHow). This has led to the propagation of certain inherited diseases and compromised immune systems in the breed.
English Bulldogs are often bred using artificial insemination rather than natural mating, which limits the gene pool. Breeding frequently occurs within closed breeding populations or closely related dogs, which increases the chances of heritable defects (AKC). Additionally, breeding solely for conformation narrows genetic diversity by excluding healthy dogs that don’t meet physical standards.
Irresponsible breeding practices aimed at supplying consumer demand have also contributed to the limited gene pool. Commercial breeders focused on profits often breed females at every heat cycle without proper health testing. These practices have been disastrous for the breed’s genetic viability and have led to extremely inbred dogs prone to health issues.
Efforts to Increase Genetic Diversity
There have been some efforts in recent years to try to increase the genetic diversity of the English bulldog breed through careful outcrossing programs. Outcrossing involves breeding a purebred dog with another purebred from a different breed that does not have overlapping health issues. The goal is to bring in new genes from the outcross breed to improve health and add diversity to the gene pool, while preserving the essential traits of the original breed.(1)
One example is the Leavitt bulldog, which was created by breeding English bulldogs with Olde English Bulldogges. This introduced new genetic material into the line while maintaining a similar bulldog appearance and temperament. Another outcrossing program bred English bulldogs with American Staffordshire terriers. More research and careful breeding programs will be needed to significantly improve the diversity and health of the breed in the long-term.
Viability of the Breed
The future viability of the English Bulldog breed is a major concern due to the extreme lack of genetic diversity. According to studies, English Bulldogs today suffer from a host of genetic health problems due to decades of intensive inbreeding and closed stud books (Davis et al, 2017). Researchers estimate that the genetic diversity of the breed is so low that they have just 37% of the diversity present in the average dog breed (Davis et al, 2017). This puts them at high risk for illnesses and threatens the continuation of the breed.
Some predictions indicate that without an increase in genetic diversity, the breed may face extinction within the next few decades (Science Alert, 2016). Experts recommend outcrossing English Bulldogs with other breeds in a careful, selective manner to improve the gene pool. However, doing so may cause them to deviate too far from the breed standard and no longer qualify as English Bulldogs (Science Alert, 2016). This represents an ethical dilemma for breeders and kennel clubs. While outcrossing may preserve English Bulldogs for the future, it could also end the existence of the breed as it is known today.
Overall, the extremely limited genetic diversity of modern English Bulldogs is the most significant threat to the future viability of the breed. Without greater diversity, the breed is predicted to continue suffering from poor health and potentially go extinct. Experts agree that increasing diversity through careful outcrossing programs is likely necessary for the breed’s survival, even if that causes divergence from the current breed standards.
Conclusions
In summary, the English bulldog has experienced a significant loss of genetic diversity due to selective breeding practices over the past few centuries. The breed’s small founding population and closed stud book have further limited the gene pool.
This lack of genetic diversity has led to severe health issues for English bulldogs including breathing difficulties, overheating, allergies, hip and elbow dysplasia, and certain cancers. Their physical structure also makes breeding and birthing difficult.
To improve the breed’s viability for the future, outcrossing with other breeds has been proposed to increase genetic diversity. Additional steps like mandatory health testing for breeding dogs, public education, and changes to breed standards could also help. But progress has been slow.
While the English bulldog remains popular due to its unique appearance and temperament, without greater genetic diversity it may struggle to thrive as a breed over the long term. More diversity would reduce health issues and could enable English bulldogs to live happier, healthier and longer lives.
References
[1] The Kennel Club. “Bulldog Breed Standard.” https://www.thekennelclub.org.uk/services/public/breed/standard.aspx?id=6
[2] O’Neill, D.G. et al. “Demography and disorders of the French Bulldog population under primary veterinary care in the UK in 2013.” Canine Genetics and Epidemiology 2.1 (2015): 1-12.
[3] Pedersen, N. et al. “The effect of genetic bottlenecks and inbreeding on the incidence of two major autoimmune diseases in standard poodles, sebaceous adenitis and Addison’s disease.” Canine genetics and epidemiology 2.1 (2015): 14.
[4] Asher, Lucy, et al. “Estimating the number of hereditary diseases in mixed-breed dogs in the UK.” Canine genetics and epidemiology 2.1 (2015): 6.
[5] Farrell, L.L. et al. “The challenges of pedigree dog health: approaches to combating inherited disease.” Canine genetics and epidemiology 2.1 (2015): 1-14.