The Rise of the Brachycephalics: by Autumn Murdock
Updated: Sep 14, 2019
The Rise of the Brachycephalics:
An Exploration of the Origins and Consequences of Breeding Dogs for Extremes
Asheville-Buncombe Technical Community College
While humans have a long history of breeding and keeping dogs for work and company, the institution of dog shows drew more attention to appearances than ever before. Due to the introduction of strict breeding standards, the physical features of many modern canines exhibit more morphological exaggerations than their ancestors. Certain brachycephalic (short-faced) breeds such as the pug, English bulldog, and French bulldog are experiencing a rise in popularity in the West. This trend coincides with climbing health insurance costs for these breeds, as they are susceptible to health problems. The most egregious and widespread condition that plagues flat-faced dogs is a potentially fatal respiratory disorder known as Brachycephalic Obstructive Airway Syndrome (BOAS), which is linked to dogs with snouts that are less than half the total length of their skulls. Breeders rely on surgical interventions rather than changes to breeding standards to alleviate the symptoms of BOAS. Potential solutions such as crossbreeding to introduce genetic diversity exist, but many breeding communities are resistant to this change, as it challenges the exclusive tradition of pedigree breeding. Some kennel clubs suggest health tests, but they do not require respiratory screenings for vulnerable brachycephalic dogs, and breeders are free to produce litters from dogs with even severe signs of respiratory distress. Veterinarian associations continue to publish research and undertake campaigns to raise awareness of this issue, and a broad change in public perception is likely necessary to successfully effect changes to breeding standards that place appropriate importance on animal health and welfare.
The Rise of the Brachycephalics:
An Exploration of the Origins and Consequences of Breeding Dogs for Extremes
For approximately 15,000 years, humans and dogs have shared close partnerships. Dogs were utilized for protection, hunting, herding, competition, and companionship. It was not until the mid-19th century that humans began to selectively breed dogs for show, to the exasperation of some sportsmen, who felt that the quality of hunting dogs was being sacrificed. When the Kennel Club was founded in 1873, breed standards were slowly developed, and middle and upper classes flaunted pedigree dogs as status symbols that were bred increasingly for form rather than function (Ritvo, 1986, pp. 241-242). The modern dog has come a long way from its ancestors, and there are now hundreds of breeds recognized by various kennel clubs around the world. Pedigree breeding has created a paradoxical phenomenon, for while dogs come in all shapes and sizes, within individual breeds there is very little genetic diversity. Inbreeding has led to reliably recognizable canine traits, but at the cost of equally predictable, breed-specific diseases. While the burden of a shallow gene pool is borne collectively by the purebred dog community, a recent rise in popularity of brachycephalic (short-faced) breeds has led to an increase in awareness of life-threatening upper respiratory complications that are almost entirely unique to the physicality of dogs bred with dramatically shortened muzzles. The result of this cultural trend is that the cute, squishy features that boost the appeal of dogs such as pugs, English bulldogs, and French bulldogs also directly cause the direst suffering for these breeds, and the increased demand for flat-faced dogs fetishizes dangerously exaggerated physical traits. Humans are the stewards of modern canine evolution, and society must question the values that lead to a morbid focus on self-indulgent, surface extremity at the loss of thoughtful integrity.
Brachycephaly: Definition and Popularity
Out of 193 dog breeds officially recognized by the American Kennel Club in 2017, French bulldogs and English bulldogs each ranked fourth and fifth respectively in popularity (AKC Staff, 2018). This number has remained relatively stable for the English bulldog, but the French bulldog climbed seven ranks in just four years. The UK Kennel Club statistics also reflect the dramatic growth in popularity of pugs (193%), English bulldogs (96%), and French bulldogs (3104%) in recent years (Fawcett et al., 2018, p. 2). Brachycephaly, which characterizes these short-muzzled dogs and twenty-one other recognized breeds, is a condition that results in the foreshortening of the canine cranial structure that leads to a classic prognathic profile which is referred to colloquially as an “underbite”. According to a report by veterinary professionals Packer and Tivers (2015) titled “Strategies for the Management and Prevention of Conformation-Related Respiratory Disorders in Brachycephalic Dogs”, this trait of prognathism is in fact a “discrete skeletal mutation” that leaves affected dogs with craniums that are “less than a third of … natural size” (p. 220). The foreshortening of the skull places the eyes in a more prominent position and creates a “bug-eyed” effect that amuses and appeals to many people. Unfortunately, although brachycephalic breeds have smaller craniofacial ratios (measurements obtained by dividing snout length by total skull length) than dogs that have not been bred for this skeletal mutation, the tongues and soft palates of these dogs remain unaffected, and are therefore too large for the surrounding skeletal structure (Packer & Tivers, 2015, p. 221). The result of such mismatched anatomy is that an upper respiratory condition known as Brachycephalic Obstructive Airway Syndrome (BOAS), which is identified by signs of chronic gasping, snorting, and panting, occurs in such an alarming number of short-faced dogs that the condition has been named after their unique cranial morphology.
Studies and Health Effects of BOAS
Several studies have examined the relationship between the dangerous obstruction of the airway passages known as BOAS and brachycephalic breeds, but two recent studies present data that links this condition to specific, measureable morphological features. In the study “Impact of Facial Conformation on Canine Health: Brachycephalic Obstructive Airway Syndrome” that compared measurements of canine skulls to the presence of BOAS in two groups with a total of 854 dogs of many diverse breeds, researchers Packer, Hendricks, Tivers, and Burn (2015) found that dogs with muzzles greater than or equal to half the length of their craniums, as measured from the back of the skull to the tip of the nose, showed no clinical signs of BOAS (p. 1). By contrast, an average of 48% of English bulldogs, 73% of French bulldogs, and 90% of pugs had obstructed airways, out of the two groups tested (Packer et al., 2015, p. 8). This study shows that there is a direct relationship between canine muzzle length and the likelihood of respiratory distress, and provides the data from which a predictive model of BOAS can be constructed to demonstrate that as the ratio between snout and cranial length decreases, the percentage of dogs affected by BOAS will increase. Packer et al.’s findings indicate that the incidence of BOAS may plummet by as much as 100% if dogs are no longer selectively bred for the skeletal mutation that allows for a muzzle less than half the length of the entire skull. This suggests that breeders could dramatically reduce, if not eradicate, a single health condition from the dog species by simply breeding dogs with faces no shorter than the limits specified within this study.
In a similar report titled “Conformational Risk Factors of Brachycephalic Obstructive Airway Syndrome (BOAS) in Pugs, French Bulldogs, and Bulldogs” that focused more on a variety of canine features and found BOAS links beyond craniofacial ratio, veterinarians Liu et al. compared more detailed anatomical measurements of three extreme brachycephalic dog breeds to the high incidence of BOAS that commonly afflicts them. Researchers used soft tape measurements of six hundred pugs, French bulldogs, and English bulldogs to record features such as skull index, nostril width, and craniofacial ratio. The researchers examined the relevance of these measurements to the BOAS grade of each dog according to an existing scale from 0 (asymptomatic) to III (severe respiratory distress), and found features such as large neck circumferences, stenotic (closed) nostrils, and obesity highly predictive of the respiratory disorder (Liu et al., 2017, p. 2). This research provides measurable results for breeders, owners, and veterinarians of brachycephalic dogs. The researchers developed an inexpensive, accessible measuring system for canine anatomy and used previously established scales for body condition (weight range) and BOAS scores that are approachable by medical professionals and laymen alike. Breeders of dogs such as pugs, French bulldogs, and English bulldogs could improve the welfare of these breeds by selecting away from the extreme features singled out by this study that lead to frequent veterinary interventions. Liu et al. revealed a compelling connection between specific physical characteristics of brachycephalic breeds and the concurrence of respiratory affliction, and provided convincing evidence that breeding dogs solely for extreme physical conformity creates health complications.
Surgical Reliance: Treating the Symptoms Rather Than the Cause
In lieu of selecting for more moderate cranial formations that could minimize breathing problems and allow dogs to live healthier lives naturally, brachycephalic enthusiasts instead turn to expensive and invasive surgical procedures to correct anatomical anomalies. In fact, surgical procedures that aim to ease the suffering caused by the very features that these dogs are bred to have are so commonplace that a clinic specializing in brachycephalic operations was opened in July of 2014 in the UK (Kenny, 2014). In this animal hospital as well as others, short-faced dogs undergo forms of canine plastic surgery that involve the removal of excess nostril tissue, as well as reductions of oversized or collapsed soft tissues of the throat and soft palate (Fawcett et al., 2018, p. 9). The inability of dogs with extremely short snouts to efficiently cool themselves through panting exacerbates respiratory labor. This is because short-faced dogs often must strain to pant, which causes the soft tissues of the upper respiratory system to become inflamed, grow larger from overstimulation, and further narrow the respiratory passage. The unfortunate result is that these dogs grow progressively hotter as BOAS takes effect, as ineffective heat regulation and respiratory distress each influence the other (Fawcett et al., 2018, p. 5). This means that affected dogs may struggle to do simple things such as go for walks on warm days, chase a ball, or even give birth naturally. While veterinarian-assisted artificial insemination and caesarean sections are not exclusive to any shape or size of dog, an overwhelming majority of certain brachycephalic breeds require this assistance. According to the report “Proportion of Litters of Purebred Dogs Born by Caesarean Section” by authors Evans and Adams, the rate of caesarean sections in French bulldogs, English bulldogs, and Boston terriers was “greater than 80%” (Evans & Adams, 2010). Because dogs with obstructed respiratory passages must breathe with increased force to circulate oxygen, the surrounding tissues sometimes weaken from the increased pressure. This eventually results in laryngeal collapse, which requires risky, emergency surgical correction (Packer & Tivers, 2015, p. 226). In extreme cases, dogs may even require tracheostomies that involve the permanent installment of a tube in the windpipe (Fawcett et al., 2018, p. 10). This operation allows the dog to bypass the airway obstruction of its own overcrowded tissues by instead breathing through the tube in its throat. These operations are by no means curative, and post-operative complications can arise. Surgery indeed eases some of the misery brachycephaly-related health problems cause, but these measures target the symptoms, rather than the cause.
Insurance Data: The Allure of Unhealthy Breeds
Given that certain brachycephalic breeds require significant veterinary intervention, it is helpful for future pet owners to make educated decisions about puppy selection. After all, medical bills quickly increase alongside frequent veterinary visits.
Insurance companies, which possess some of the most thorough statistical information on canine health-related problems available, have compiled data that shows the number of pet insurance claims made according to categories of breed and health problems. In 2017, veterinarians Feng, McConnell, O’Hara, Chai, and Spadafori published the “Nationwide Brachycephalic Breed Disease Prevalence Study”, which revealed the incidence of common health problems among all dogs. From 2007 to 2015, Feng et al. found that out of 1.27 million dogs, brachycephalic breeds had more claims for common canine diseases, and were 377% more likely than other breeds to suffer from corneal ulcers on their eyes (2017, p. 3). Even in the absence of data on breed-specific ailments such as the respiratory effects from BOAS, brachycephalic dogs experienced more problems from skin infections, heat stroke, gastrointestinal distress, and dental complications (Feng et al., 2017, pp. 5-6). These disconcerting patterns are not unique to the U.S. The article “Consequences and Management of Canine Brachycephaly in Veterinary Practice: Perspectives from Australian Veterinarians and Veterinary Specialists” by veterinarians Fawcett et al. showed a rise in canine health insurance claims in Australia as well, alongside the increasing demand for brachycephalic dogs (2018, p. 5). Fawcett et al. (2018) included pet insurance data from the company PetSure that confirmed more brachycephalic breeds require veterinary assistance than breeds with mesaticephalic (intermediate) or dolichocephalic (long) skull structures for many conditions, including inflammation of the ear canal, eyes, and stomach lining, as well as patellar luxation, which is a painful dislocation of the kneecap (p. 5). The data released by these two companies suggests that short-faced breeds of dogs are, on average, less healthy than dogs with longer faces. Uninformed dog owners who are as drawn to trendy, pinched-in, brachycephalic features as they are unable to anticipate the likely costs of vulnerable breeds, may forfeit their pet to a shelter or animal rescue in the face of expensive veterinary bills.
If the compact, flattened appearance of some of today’s most popular dogs serves no obvious utilitarian purpose, one might assume that this example of extreme human interference with the canine form stems from the novelty of the aesthetic for its own sake. Brachycephaly, which has been traced to origins in bullbaiting that has since been banned (Packer & Tivers, 2015, p. 220), still appeals to many modern pet owners despite the apparent lack of functional value. Celebrity endorsement certainly influences cultural trends of consumerism, and dog ownership is no exception to this rule. French bulldogs, especially, are the subjects of a recent increase in media exposure, and appear in social media and paparazzi photographs with celebrities like Lady Gaga and Dwayne ‘The Rock’ Johnson (Feng et al., 2017, p. 2). In the 2017 article “Why do People Buy Dogs with Potential Welfare Problems Related to Extreme Conformation and Inherited Disease? A Representative Study of Danish Owners of Four Small Dog Breeds” authors Sandøe et al. discussed the reasons why pet owners select dogs known to suffer from breed-specific health disorders. Researchers theorized that small dogs with short, round faces and prominent eyes appeal to humans’ innate nurturing instincts as these features resemble that of human infants (Sandøe et al., 2017, p. 2). This caretaking phenomenon is underscored by a self-reporting, anonymous survey administered to Danish owners of French bulldogs, chihuahuas, Cavalier King Charles spaniels, and Cairn terriers that found a positive relationship between the frequency of expensive veterinary interventions and high levels of owner attachment to the afflicted dogs (Sandøe et al., 2017, p. 2). These findings may either show that people undergo a psychological phenomenon of increased attachment the more they invest in an animal, or instead reveal that the overall neediness of a dog directly affects the level of attachment that an owner feels from providing interventional care. If the latter statement is true, this suggests that human attachment to brachycephalic breeds is partly founded on the appeal of infantile helplessness and a desire for the opportunity to come to the aid of a dog that is born with a congenital handicap. In either case, it is apparent that public perception plays an important role in influencing the direction of breeding trends. If the public responds more favorably to endearingly diminutive, compressed appearances than humane, evidence-based, morphologically sound alternatives that are in the best interest of dogs, then breeders will supply that demand.
Veterinary Activism and Changing the Perception of What is “Normal”
If many of the health problems that arise from brachycephalic conformation might be obviated by breeding dogs with more balanced, symmetrical anatomy, then there are several opportunities to remove obstacles that stand in the way of change. Part of the problem of the prevalence of respiratory disorders in brachycephalic breeds is the perception that constant gasping, snorting, and tongue-lolling is normal for certain breeds of dogs, and not others. Fawcett et al. (2018) found that “58% of owners of dogs with BOAS reported that their dog did not have a breathing problem, despite reporting a high frequency and severity of clinical signs” (p. 17). Veterinarians, who treat all breeds of dogs and are therefore well-versed on what constitutes a normal, healthy specimen, can influence public misconceptions of extreme morphology and the effects it generates. The fact that most brachycephalic dogs show some signs of BOAS does not mean that chronically labored breathing and a tendency toward overheating are normal signs of an optimally functioning dog. Some professional veterinary associations are already taking a public stand against breeding according to extremes of canine morphology and call upon brands to no longer publish advertisements that contribute to the popularity and normalization of Dachshunds, whose squat, oblong morphology leads to orthopedic ailments, or brachycephalics, such as the pug (Fawcett et al., 2018, p. 19). However, such solutions stray into the territory of breed-specific bans, which are highly divisive. The British Veterinary Association (BVA) launched a campaign called “Breed to Breathe” as a response to the rising popularity of brachycephalic dogs. The BVA seeks to encourage medical research, participate in public education, and influence breeding by “ensuring healthier future generations of dogs” (“Health and Welfare of Brachycephalic Dogs”, n.d.). In addition to raising awareness through public outreach and pet owner education, veterinarians may refuse to facilitate artificial insemination and routine puppy deliveries by Caesarian section that remove the incentive to breed healthier dogs that are better suited to natural reproduction.
The Success and Controversy of Outcrossing
Another contribution to the proliferation of disease and extreme conformation is inbreeding and the incredibly selective and exclusive breeding practices that are used to maintain pedigrees. It is not unusual for dog breeders to mate canine relatives within two generations of one another. This practice safeguards against the loss of highly valued and reliable traits, but also leaves closely related dogs susceptible to repetitive ailments. In “The Challenges of Pedigree Dog Health: Approaches to Combating Inherited Disease”, authors Farrell, Schoenebeck, Wiener, Clements, and Summers discussed the lack of genetic diversity that causes many of the diseases that plague purebred dogs, and reviewed previously successful strategies for breeding away from adverse traits that could be adopted by kennel clubs. Farrell et al. (2015) asserts that the lack of diversity of modern pedigree dogs largely arose from the common overuse of a few popular male specimens as sires for numerous puppies (p. 2). One possible solution to the problem of inbreeding is a limit on the number of litters one male dog may sire. Another useful approach is outcrossing, which is a technique in which a purebred dog is bred with a dog of another breed to encourage genetic diversity and rehabilitate the breed. In one case of successful outcrossing, a mutation associated with the characteristic spots of the Dalmatian breed known to cause a urinary system disorder was eliminated from the line when geneticist and breeder Robert Schaible bred a Dalmatian with a Pointer; The crossbreed was then reintroduced to the Dalmatian line, which after ten generations was “free of the disease while still meeting the breed standards and being almost genetically indistinguishable to purebred Dalmatians” (Farrell et al., 2015, p. 9). This article provides evidence of successful techniques that may be applied to some breeds for the reduction of hereditary disease without sacrificing unique, observable breed traits. However, although backcrossing allows for a breed to maintain Kennel Club registry according to genetic testing after several generations, the practice is still highly contested among breeding circles, and scandalized opponents delayed the acceptance of the new and improved Dalmatian line for thirty years (Farrell et al., 2015, pp. 9-10). Although some breeds carry a high risk for certain diseases, many breeders frown upon crossbreeding, and this solution is unlikely to find unanimous favor within an efficient timeframe. The institution of pedigree breeding is steeped in a tradition that is slow to accept change, even when scientifically proven to be beneficial. An integrative approach to the improvement of breeding practices will likely be more palatable, and therefore advantageous in the present, than any single, contentious solution that waits for the future.
The Need for Mandatory Upper Respiratory Screenings
The solution which perhaps holds the most immediately beneficial potential is to make upper respiratory screenings mandatory for high-risk breeds. Breed-specific health and genetic tests are concepts that are not new to kennel clubs. However, some tests are optional recommendations, while others are requirements upon which breeder registration depends. The American Kennel Club, which lists health testing requirements in alphabetical order according to breed name on the organization’s official website, lists no requirements for the English bulldog, and while pugs and French bulldogs must have eye, hip, and knee exams, none of these breeds require upper respiratory screenings, despite the considerable prevalence of BOAS in brachycephalic breeds (American Kennel Club, n.d.). This is a surprising oversight, as Fawcett et al. (2018) determined that the lifespans of brachycephalic dogs are on average four years shorter than dogs with moderate skull morphology (p. 2). This implies that the health problems that afflict short-nosed breeds interfere with the ability of these dogs to live long, healthy lives. The Kennel Club (2018) of the UK provides a voluntary certification program for breeders known as the “Assured Breeders Scheme” that incentivizes health screenings with discounts and provides on-site screenings every three years to encourage breeders to follow humane practices. Compliant breeders receive an “Assured Breeder” seal from the organization, as well as free listings for puppies (The Kennel Club, 2018). Participation in this program is optional, and health tests, while recommended by the Kennel Club, are unfortunately not required for English bulldogs, pugs, or French bulldogs. This leaves breeders free to breed less than healthy brachycephalic dogs regardless of any respiratory difficulties that the dogs exhibit. The Kennel Club also partnered with the University of Cambridge in early 2019 to create a screening system that ranks the severity of BOAS present in extreme brachycephalic breeds before and after physical exertion. Breeders are not required to submit their dogs to the screening system, known as the “Respiratory Function Grading Scheme” (The Kennel Club & University of Cambridge, 2019), and may choose whether to heed veterinarians who caution against breeding dogs that show the severest signs of respiratory distress, but this is indeed a step in the right direction. The “Respiratory Function Grading Scheme” uses a similar approach to that of Liu et al.’s study of BOAS, and even ranks the health of brachycephalic dogs according to the same metric contained within that study. This suggests that recent scientific literature published on the effects of breeding for extreme conformation has begun to draw attention to the problems that strict adherence to physical standards creates.
Through the practice of selective breeding, humans have successfully shaped dogs to have a diverse range of physical and temperamental traits according to cultural values of utility, aesthetics, and companionship. Many of these creatures are loyal, intelligent, hardworking, and are capable of being both gentle and fierce. No other animal shares a closer partnership with the human species. If the current state of dogs reflects the values of society, then humans have an obligation to examine the reasons behind the prioritization of extreme physical features for amusement, as well as the restrictive exclusivity of pedigree that has led to the detriment of canine health and quality of life. As in The Picture of Dorian Gray (Wilde, 2015), which depicts the relinquishment of one’s soul in exchange for a singular, obsessive focus on corporeal manifestation, current breeding practices risk the unthinking hedonism of surface features at the expense of underlying decadence.
AKC Staff. (2018, March 28). Most popular dog breeds – full ranking list. American Kennel Club. Retrieved from https://www.akc.org/expert-advice/news/most-popular-dog-breeds-full-ranking-list/
Evans, K. M., & Adams, V.J. (2010). Proportion of litters of purebred dogs born by caesarean section [Abstract]. Journal of Small Animal Practice, 51(2), 113-118.
Farrell, L. L., Schoenebeck, J. J., Wiener, P., Clements, D.N., & Summer, K.M. (2015). The challenges of pedigree dog health: Approaches to combating inherited disease. Canine Genetics & Epidemiology, 2(3), 1-14. doi:10.1186/s40575-015-0014-9
Fawcett, A., Barrs, V., Awad, M., Child, G., Brunel, L., Mooney, E., … McGreevy, P. (2018). Consequences and management of canine brachycephaly in veterinary practice: Perspectives from Australian veterinarians and veterinary specialists. Animals, 9(1), 1-25. doi:10.3390/ani9010003
Feng, T., McConnell, C., O’Hara, K., Chai, J., & Spadafori, G. (2017, March). Nationwide brachycephalic breed disease prevalence study [PDF file]. Retrieved from http://nationwidedvm.com/wp-content/uploads/2017/03/NWBrachycelphalicStudy0317.pdf
Health and welfare of brachycephalic dogs. (n.d.). British Veterinary Association. Retrieved from https://www.bva.co.uk/news-campaigns-and-policy/policy/companion-animals/brachycephalic-dogs/
Health testing requirements. (n.d.). American Kennel Club. Retrieved from https://www.akc.org/breeder-programs/akc-bred-with-heart-program/requirements/health-testing-requirements/
The Kennel Club. (2018). Breed specific requirements and recommendations including health screening [PDF file]. Retrieved from https://www.thekennelclub.org.uk/media/9846/abs_breed_specific_requirements_and_recommendations_web.pdf
The Kennel Club and University of Cambridge launch vital scheme to improve health of pugs, French bulldogs and bulldogs. (2019, February 14). The Kennel Club. Retrieved from https://www.thekennelclub.org.uk/press-releases/2019/february/the-kennel-club-and-university-of-cambridge-launch-vital-scheme-to-improve-health-of-pugs-french-bulldogs-and-bulldogs/
Kenny, J. (2014). RVC opens first specialist clinic in UK for short-muzzled dogs. Royal Veterinary College University of London. Retrieved from https://www.rvc.ac.uk/news-and-events/rvc-news/rvc-opens-first-specialist-clinic-in-uk-for-short-muzzled-dogs
Liu, N. C., Troconis, E. L., Kalmar, L., Price, D. J., Wright, H. E., Adams, V. J., … Ladlow, J. F. (2017). Conformational risk factors of brachycephalic obstructive airway syndrome (BOAS) in pugs, French bulldogs, and bulldogs. PLoS ONE, 12(8), 1-25. doi:10.1371/journal.pone.0181928
Packer, R. M., Hendricks, A., Tivers, M. S., & Burn, C. C. (2015). Impact of facial conformation on canine health: brachycephalic obstructive airway syndrome. PLoS ONE, 10(10), e0137496. doi:10.1371/journal.pone.0137496
Packer, R. M., & Tivers, M. S. (2015). Strategies for the management and prevention of conformation-related respiratory disorders in brachycephalic dogs. Veterinary Medicine (Auckland, N.Z.), 6, 219–232. doi:10.2147/VMRR.S60475
Ritvo, H. (1986). Pride and pedigree: The evolution of the Victorian dog fancy [PDF file]. Victorian Studies, 29(2), 227-253. Retrieved from https://www.fcusd.org/cms/lib/CA01001934/Centricity/Domain/1064/Pride%20and%20Pedigree%20The%20Evolution%20of%20the%20Victorian%20Dog%20Fancy.pdf
Sandøe P, Kondrup SV, Bennett PC, Forkman B, Meyer I, Proschowsky HF, et al. (2017). Why do people buy dogs with potential welfare problems related to extreme conformation and inherited disease? A representative study of Danish owners of four small dog breeds. PLoS ONE 12(2): e0172091. doi:10.1371/journal.pone.0172091
Wilde, O. (2015). The picture of Dorian Gray. New York, NY: Barnes & Noble, Inc.