The French bulldog is one of the most popular dog breeds in many countries around the world (1–3). The brachycephalic appearance is attractive to many humans, and selective breeding for a short, rounded head with large, protruding eyes is not restricted to dogs but is also found in other companion animals like cats and rabbits (4, 5). According to a British study, appearance was the factor that most influenced owners of brachycephalic dogs to acquire their breed, followed by suitable breed size, and a perception that the breed is good with children and generally makes a good companion dog (6). The perceived health of the breed was seen to be less influential in decision making among brachycephalic dog owners compared to owners of non-brachycephalic dog breeds (6, 7).

The characteristic cranial conformation and short snout of the brachycephalic dog breeds leave reduced space for internal soft tissue, such as the soft palate and the tongue, and this can lead to obstruction of the airways (8, 9). This results in a predisposition to breathing difficulties and exercise intolerance in brachycephalic dogs. When these problems get to a very severe level of respiratory compromise, they are collectively known as Brachycephalic Obstructive Airway Syndrome (BOAS) (9). The prevalence of BOAS in the three classic brachycephalic breeds (English bulldog, French bulldog and pug) is high. Approximately 50% of dogs from the three breeds were BOAS-affected when the respiratory function was measures by whole-body barometric plethysmography (WBBP) in a UK study (10). A study of upper respiratory tract disorders based on electronic patient records from veterinary practices in England within the VetCompass Program found prevalences of 19.5, 20.0 and 26.5% for English bulldog, French bulldog, and pug, respectively (8). In addition, French bulldogs were highly predisposed to BOAS with an odds ratio of 30.9 in a study based on random sampling of French bulldogs and non-French bulldogs under primary veterinary care in England (11).

Several studies have shown that many owners fail to recognize or react to clinical signs of BOAS because features like snoring and wheezing are considered “charming” and a normal breed characteristic rather than symptoms of disease (7, 12). A similar effect has been found in studies of obesity, where both parents and dog owners tend to underestimate weight or body condition score (BCS) when asked to evaluate their own children or dogs (13, 14). One-third of the dog owners in a Swedish study underestimated the body composition of their own obese dogs but responded well to a standardized education program and were subsequently able to assess BCS comparable to veterinary health care personnel (14). Regarding BOAS, a study from the UK found that although it was possible to improve public understanding and awareness of BOAS through educational interventions, normalization of its clinical signs was still prevalent (15).

In addition to BOAS, French bulldogs are also predisposed to a range of other diseases. These include dermatological problems like allergies and skin fold dermatitis (16, 17), spinal diseases including intervertebral disk disease, congenital vertebral malformations, and tail malformation (18, 19), eye diseases including corneal ulcers, prolapse of the nictitans gland, and entropion (17, 20, 21), and problems related to reproduction, especially an increased risk of dystocia (22). High veterinary costs and reduced life span are some of the consequences of the high disease burden of French bulldogs (23, 24), yet many owners state that they would acquire the breed again in future (7).

Public awareness and concern about the health and welfare of purebred dogs has increased in recent decades, particularly fueled by the BBC1 television documentary ‘Pedigree Dogs Exposed’, which aired in August 2008 (25). In 2024, a Swedish study found a high level of awareness among dog owners, breeders, show judges, and veterinarians of conformation-related health issues in brachycephalic dogs (26). Most participants in the survey agreed that the health of brachycephalic breeds is compromised and that measures should be taken to improve the situation.

The organized dog world has been criticized for not doing enough to ensure healthy breeding and the majority of show judges in the Swedish study agreed either fully or partly that it is essential to follow the breed standard, even if it can be associated with health issues related to their physical appearance, while all other stakeholders mostly disagreed (26). The debate about extreme conformation in dogs has emerged in many countries and new legislation concerning dog breeding has been enforced in countries like the Netherlands (27), Germany (28, 29), Austria (30), and Denmark (31). The Norwegian Supreme Court recently concluded that further breeding of cavalier King Charles spaniels with the current genetic pool is in violation of the Animal Welfare Act, and that English bulldogs must be bred under a breeding program aimed at reducing the occurrence of diseases such as BOAS (32).

Various screening models have been developed with the hope of moving the brachycephalic breeds in a healthier direction by selective breeding. The test most widely adopted internationally is the Respiratory Function Grading (RFG) scheme developed by Jane Ladlow and coworkers at the University of Cambridge (33). This test consists of a physical examination that includes grading nostril stenosis, auscultation of respiratory sounds, a 3-min exercise test, and repeated auscultation. After the test, the dog is assigned one of four grades: 0 (BOAS free), 1 (mild BOAS), 2 (moderate BOAS), or 3 (severe BOAS) (34). BOAS grading can only be performed by veterinarians who have attended a qualifying course. The RFG scheme is currently implemented in Australia, Austria, Belgium, the Czech Republic, Denmark, Germany, Hungary, Iceland, Ireland, Mexico, the Netherlands, New Zealand, Norway, Portugal, Romania, Sweden, Switzerland, the UK, and the US (35, 36). The International organization for dogs, Fédération Cynologique Internationale (FCI), also supports the RFG scheme (37). The Danish Kennel Club (DKC) implemented a mandatory breeding program based on BOAS grading from August 1, 2023. After this date, English bulldog, French bulldog, and pug must have a BOAS grade of 0 or 1 prior to mating for their offspring to obtain a DKC pedigree (38). After July 1, 2025, when new Danish legislation came into force, all dogs belonging to the three breeds used for breeding must have a BOAS grade of 0 or 1 regardless of pedigree (31).

The Finnish Kennel Club (FKC) uses a BOAS test that is slightly modified from the RFG scheme and includes auscultation for respiratory sounds before and after a brisk, time-limited 1,000 m walk, evaluation of nostril stenosis, registration of body temperature, and measurement of the craniofacial ratio (9) to evaluate muzzle length. As part of a validation of the Finnish BOAS scheme, heritability estimates for the severity of BOAS were calculated for parent–offspring pairs of English bulldogs, French bulldogs, and pugs with at least one BOAS-graded parent (h² = 0.39) or both parents BOAS graded (h² = 0.48) (39). These heritability estimates indicate that the Finnish system for BOAS grading has the potential to be used as a selection tool to obtain less-affected offspring.

Supplementary tools like open breed registries or cross breeding projects for brachycephalic dog breeds have been introduced in some countries. When a breed has an open breed registry, it is possible to introduce new individuals without a pedigree to the organized pedigree dog registry. In Denmark, the English bulldog, French bulldog and pug breed registries were opened by May 1, 2024. To enter the Danish Kennel Club registry, a dog must have a BOAS grade of 0 or 1 and its phenotype must be evaluated and approved by an official show judge (40). One of the motivations behind open breed registries is to increase the gene pool of the pedigree population. ID marking and registration in the Danish Dog Registry (DDR) is mandatory in Denmark (41), and data from the DDR and registration figures provided by the DKC show that the immense popularity of the French bulldog has led to an increasing proportion of the Danish population of French bulldogs being bred outside the kennel club. In 2024, a total of 1,531 French bulldogs were registered in the Danish Dog Registry, but only 165 (11%) had a pedigree from the DKC (42, 43).

In Finland, the FKC has introduced several cross breeding projects in recent years, one of which involves the French bulldog, with a statement on the FKC website that “The aim of the cross breeding project is to improve the breed’s health status and to decrease the exaggerated traits in the appearance of the breed” (44). The suggested breeds for cross breeding with the French bulldog are: American Staffordshire terrier, Jack Russell terrier, mittel spitz, Papillon/Phalene, Danish-Swedish farmdog, and Staffordshire bull terrier (44). The offspring of deliberate cross breeding projects are normally registered in a separate register in the kennel club and introduced to the purebred breeding population according to defined criteria, which can include health screening results or phenotypic evaluation.

The focus of the present study is on Danish dog owners’ perceptions of breed-related health problems in French bulldogs and their attitudes toward BOAS grading and the specific aims were to: (1) report the prevalence of specific health problems among the dogs of respondents; (2) assess how problematic to the breed the owners find each health issue; (3) determine the extent to which owners have consulted a veterinarian about the health issues; (4) examine how respondents perceive the health of French bulldog compared to other breeds, as well as the health of their own dog compared to other French bulldogs, and how this is influenced by owner characteristics and the disease load of the respondent’s own dog; (5) identify the prevalence of eight specific clinical signs associated with BOAS and their correlation with the owners’ perception of their dog having breathing problems; and investigate how owner characteristics, the general perceived health status of the breed, the perceived health status of their own dog, and the owner’s attitude toward BOAS grading influence the (6) likelihood of owners’ plan of having their current dog BOAS-graded in the future and preferring a puppy from BOAS-graded parents; and (7) the likelihood of acquiring another French bulldog or recommending French bulldogs to others. The part of the present study that relates to perceptions of health is very close to a previous UK study that used almost the same approach and set of questions although the UK study was bigger and covered more breeds (45, 46).

The study was part of a larger study that also included breeders. Unfortunately, not enough answers were received from breeders to allow for a proper analysis. Therefore, the questions aimed at breeders were excluded from the present study.

A total of 653 responses were received from Danish owners of French bulldogs, of which 452 were completed questionnaires.

The majority of the responding dog owners were female (N = 411, 90.9%) and more than half of the responses came from owners who were either between 35 and 44 years old (N = 114, 25.2%) or between 45 and 54 years old (N = 139, 30.8%).

The distribution of male and female dogs was 255 (56.4%) male and 197 (43.6%) female dogs. With 49.6% (N = 224), half of the dogs were aged between 1 and 3 years, while about one-third fell within the 4 to 9-year age range (N = 153, 33.8%). Additionally, 10.6% (N = 48) of the dogs were younger than 1 year, and 6.0% (N = 27) were aged 10 years or older, with the oldest being 14 years. Approximately two thirds of the dogs were intact (N = 288, 63.7%), while 164 (36.3%) were neutered. A total of 65.0% (N = 294) of the 452 dog owners stated that the dog in question was their first French bulldog.

This paper presents the results of a questionnaire study among Danish owners of French bulldogs focusing on their perception of the current health status of the breed in general and their own dog specifically, and how this related to their opinion of BOAS grading as a tool to improve respiratory health among French bulldogs in future and their tendency to either reacquire or recommend the breed to others.

The results are in line with other studies (11, 17) and confirm that the French bulldog is a breed with a high disease load. Nearly one third of the dogs in the present study had allergies or breathing problems. Furthermore, over half of the dog owners stated that poor respiratory health is problematic for the breed. More than half of the owners also perceived the French bulldog to be less healthy than other breeds, while 64% considered their own dog to be healthier than other French bulldogs. The individual dog’s perceived health also played a role, as owners who observed fewer health problems in their own dogs were more likely to state that French bulldog is healthier than other breeds and that their own dog is healthier than other French bulldogs. Despite the significant prevalence of health issues, more than 80% of the respondents expressed a desire to own another French bulldog, and over 60% would recommend the breed to others.

Both the tendency to rate one’s own dog healthier than the average and the urge to acquire another brachycephalic dog have also been described in other studies (7, 12). The previously mentioned questionnaire study performed in the UK across the three “classic” brachycephalic dog breeds (English bulldog, French bulldog and pug) reported similar results regarding the most common diseases, yet 70.9% of the 2,168 respondents still considered their own dog to be in very good health or the best health possible (45). The subsequent study based on the same questionnaire data found that 93% of the 2,168 owners were highly likely to acquire their breed again and 65.5% would recommend the breed to other owners (46). The study analyzed factors affecting what has been termed “dog breed loyalty” (48) and concluded: “Although owners are initially attracted to the distinctive appearance of brachycephalic dogs, perceived breed-related behavioral traits are a core component of why owners perceive their breed positively, alongside the strong emotional bonds they inspire” (46). It is relevant to mention that emotional bonds or pet attachment have been shown to influence the ability to evaluate one’s own animal objectively with respect to diseases and traits like BCS. The extent to which owners have favorably distorted views of their pets has been found to be positively correlated with pet attachment (49).

A significant difference between breeds in the formation of owner-dog bonds was also identified in a representative study among Danish owners of four dog breeds (Cairn terrier, cavalier King Charles spaniel, Chihuahua, and French bulldog). The study compared motivational factors behind acquisition, the prevalence of health problems, quality of the owner-dog bond, as well as the intention to acquire another dog of the same breed (7). The Lexington Attachment to Pets Scale (LAPS) (50) was used to quantify the emotional attachment between owners and dogs and the results revealed that higher levels of health and behavioral problems did not appear to have a negative impact on the quality of the owner-dog relationship. On the contrary, high levels of health and behavioral problems in Chihuahuas and cavalier King Charles spaniels were positively correlated with high levels of owner-dog attachment, suggesting that caregiving behavior may reinforce the formation of strong owner attachments. Despite the high health care burden, many owners still intend to reacquire a type of dog that they now personally know is likely to have serious health issues. However, both the present study and the Danish study from 2017 found that as the number of health problems increased, there was a corresponding decrease in the owners’ intention to acquire another French bulldog (7). Apparently, some owners perceive the long-term commitment and potential costs of managing a higher number of health issues as burdensome, which can deter them from acquiring another dog of the same breed.

It has been suggested that pre-purchase consultations by veterinarians could be seen as an opportunity to influence decisions to acquire or re-acquire brachycephalic dogs, but according to a British study, many veterinarians find it difficult to overcome barriers like a fear of negative consequences of discussing brachycephalic health and welfare, including the risk of compromising their relationship with an existing client (51).

There was a high incidence of clinical signs like snoring when asleep (72.6%) and grunting (62.4%) reported in the present study. In addition, nearly half of the dogs presented with heat intolerance, which is likely to affect the owner’s ability to walk their dogs and engage in other outdoor activities during the summertime. The high level of reported BOAS symptoms indicates that owners are able to recognize these symptoms in their dogs, yet relatively few respondents consulted a veterinarian about breathing problems. One possible explanation is that the only treatment available is surgical correction, and financial considerations may discourage some owners from seeking veterinary advice and potential treatment. However, it may also be because some owners underestimate the seriousness of the problem, partly because it is such a common problem in the breed. The results may reflect a form of acceptance of health issues at the individual level, to which owners may adjust their perception based on the general assessment of the breed’s well-known health issues.

A study from 2019 evaluated the correlations between brachycephalic syndrome and phenotypic characteristics like nostril stenosis and neck girth in a population of 69 French bulldogs from Denmark (52). The authors concluded that there is a long way to go before French bulldogs can be bred to breathe well. However, a lot has happened in the dog-breeding community since 2019, in particular with the development and distribution of standardized BOAS-grading tools like the Respiratory Function Grading (RFG) scheme developed by Jane Ladlow and coworkers at the University of Cambridge (33).

Grading of BOAS using the Cambridge RFG scheme only became available in Denmark a short time before the questionnaire of the present study was distributed to owners of French bulldogs. Despite this, only one third of respondents stated that they had never heard about it. This may be attributed to widespread attention from the media when it comes to health problems of purebred dogs, in particular brachycephalic dogs. The present study reveals significant support for BOAS grading with more than 80% of respondents stating that BOAS grading is a good initiative that has the capacity to improve the health of the breed. In addition, 79% of respondents stated that they will prioritize a puppy from BOAS-graded parents when acquiring their next French bulldog.

The effect of using the Cambridge RFG scheme as a tool to improve the health of brachycephalic breeds through selective breeding has not yet been evaluated and has some limitations. Critics argue that the grading system lacks standardization, which can lead to variability in assessments among veterinarians (53). This subjectivity raises concerns about the reliability and consistency of the grading results. Furthermore, the reliance on physical examinations and exercise tests may not adequately capture the full spectrum of respiratory issues faced by brachycephalic dogs, thus presenting challenges in achieving a universally accepted standard (39). In addition, some critics claim that the scheme promotes the breeding of animals that still have some level of respiratory impairment and that the scheme does little to modify well-known conformational risk factors of BOAS like craniofacial ratio, eye width ratio and neck girth ratio (10). As a result, there is ongoing debate within the veterinary community about the effectiveness of the Cambridge RFG scheme and the potential for inconsistencies in its application in breeding decisions. This lack of consensus underscores the necessity for continued research and the development of more objective measures to ensure the welfare of breeds with a high prevalence of BOAS. The heritability estimates, that were calculated from the Finnish version of the BOAS test, seem promising (39). However, to make progress, adequate population size in order to avoid inbreeding (52, 54, 55) in combination with the willingness to prioritize health over other selection criteria are necessary regardless of the method.

To conclude, the present study found that allergies and breathing problems were the two most prevalent diseases among French bulldogs and that more than half of the 452 owners perceived these diseases as problematic for the breed. Even though owners were fully able to identify the clinical signs of breathing difficulties, they seldomly, compared to the other reported diseases, consulted a veterinarian about them. The study reproduces the high level of breed loyalty among owners of French bulldogs seen in other studies as well as a tendency to rate one’s own dog healthier than the average. A change of priorities in pedigree dog breeding is underway in many countries (57), in some cases supported by legislative initiatives and this may be reflected in the generally positive attitude toward BOAS grading as a tool to improve the respiratory health of the French bulldog breed.