A genetic assessment of the English bulldog

'All I do is fight fires': Qualitative exploration of UK veterinarians' attitudes towards and experiences of pre-purchase consultations regarding brachycephalic dogs

BACKGROUND

Demand for brachycephalic dogs has dramatically increased over the past decade, despite growing evidence of strong associations between brachycephaly and severe, chronic disease. Positive post-purchase attitudes of owners towards brachycephalic dogs are highly intractable, facilitated by normalisation of breed-related disease and strong dog-owner bonds. Veterinarian-led pre-purchase consultations (PPCs) have been promoted as an opportunity to influence acquisition decisions regarding brachycephalic dogs.

METHODS

Using reflexive thematic analysis, this qualitative study investigated veterinarians' attitudes towards, and experiences of, engaging in PPCs for brachycephalic dogs.

RESULTS

Veterinarians described significant structural barriers, such as lack of time and staff, and perceptual barriers, such as perceived futility, negative outcomes of PPCs and public distrust in the profession, that combine to inhibit many veterinarians from offering or delivering brachycephalic PPCs. Some of these barriers are intractable at an individual-veterinarian level and lead to moral distress due to conflicts between veterinarians' responsibilities to animal welfare versus clients' and business needs, with resultant censorship of authentic views on brachycephalic ownership compromising professional integrity and autonomy.

LIMITATIONS

Wider views and/or experiences may exist outside of the sampled population.

CONCLUSION

Stronger veterinary leadership, including from the RCVS, BVA and veterinary corporates, is now urgently required to build profession-wide solutions that overcome the barriers identified to create public-facing consensus and innovative solutions to the 'brachycephalic crisis'.

Dermatological Problems of Brachycephalic Dogs

Brachycephalic dogs are not only affected by brachycephalic obstructive airway syndrome (BOAS), but are also frequently referred to veterinary dermatologists for skin conditions, with English bulldogs and pugs particularly over-represented. Some skin diseases, such as skin fold dermatitis, are directly associated with the abnormal anatomic conformation of brachycephalic dogs, while for others, such as atopic dermatitis and viral pigmented plaques, there is an underlying genetic basis or a general predisposition. Anatomic alterations associated with brachycephaly, leading to fold formation of the skin and stenosis of the ear canal, together with primary immunodeficiencies described in some breeds, favor the development of pyoderma, Malassezia dermatitis, and otitis externa/media. In addition, the frequently neglected but often lifelong dermatological problems of brachycephalic dogs are an important consideration when discussing genetic and medical conditions affecting the welfare of those dogs. Here we review the current state of knowledge concerning dermatological problems in brachycephalic dogs and combine it with clinical experience in the management of these challenging disorders.

Evaluation of Genetic Diversity in Dog Breeds Using Pedigree and Molecular Analysis: A Review

Domestic dogs are important for many economic and social reasons, and they have become a well-known model species for human disease. According to research, dog breeds exhibit significant levels of inbreeding and genetic diversity loss, decreasing the population’s ability to adapt in certain conditions, and indicating the need of conservation strategies. Before the development of molecular markers, pedigree information was used for genetic diversity management. In recent years, genomic tools are frequently applied for accurate estimation of genetic diversity and improved genetic conservation due to incomplete pedigrees and pedigree errors. The most frequently used molecular markers include PCR-based microsatellite markers (STRs) and DNA sequencing-based single-nucleotide polymorphism markers (SNP). The aim of this review was to highlight genetic diversity studies on dog breeds conducted using pedigree and molecular markers, as well as the importance of genetic diversity conservation in increasing the adaptability and survival of dog breed populations.

Genetic Structure of the Ca Rater Mallorquí Dog Breed Inferred by Microsatellite Markers

Ca Rater Mallorquí is a dog breed from the Island of Mallorca (Spain) traditionally used as a hunting and ratting dog to prevent disease spread and economic losses related to rodent activities on farms. However, the census data shows a population decline that should be addressed by implementing a conservation program. The first step to implementing a conservation plan is knowing the genetic situation of the Ca Rater Mallorquí population. Therefore, we aimed to genetically characterise the breed in our study. We analysed 33 microsatellites recommended by the International Society of Animal Genetics (ISAG) in 77 samples. Data were obtained from 13 samples of Balearic, Spanish, and international dog breeds to study the genetic diversity among breeds. The population did not significantly deviate from the Hardy-Weinberg equilibrium with heterozygosity (Ho) of 0.655 and expected heterozygosity (He) of 0.685. The Wright's fixation indices, the Factorial Correspondence Analysis (FCA), a dendrogram representing Reynolds genetic distance between populations, and the pairwise F_ST values establish the Ca Rater Mallorquí as an independent breed distinct from the Balearic, Spanish, and international breeds.

Vertebral vascular canal dysplasia in French and English Bulldogs: Clinical, CT, and MRI characteristics and prevalence

The authors have observed a vertebral anomaly in French and English Bulldogs and termed this anomaly "vertebral vascular canal dysplasia (VVCD)." No previously published descriptions of this anomaly were found. The aims of this retrospective, multi-institutional, observational study were to (1) describe the clinical, CT, and MRI characteristics of VVCD, and (2) estimate the prevalence and describe the characteristics of VVCD in a group of French and English Bulldogs. For descriptions of the anomaly, medical records and imaging studies of nine clinical cases with VVCD from several countries were reviewed. For estimation of prevalence, imaging studies of French and English Bulldogs from the United Kingdom (UK) and Italy were reviewed. All clinical case dogs had ≥5 thoracic vertebrae with VVCD affecting >50% of vertebral body height (VBH). The prevalence of VVCD involving ≥1 thoracic vertebra in the UK population (CT identified) of English Bulldogs and French Bulldogs was, respectively, 83.3% (30/36) and 68.3% (28/41). English Bulldogs had significantly more thoracic vertebrae with VVCD than French Bulldogs (P = < 0.01). The prevalence of VVCD in ≥1 thoracic vertebra in the Italian population (MRI identified) of English Bulldogs and French Bulldogs was, respectively, 21.7% (5/23) and 6.6% (7/106). Vertebral vascular canal dysplasia was observed in normal as well as in malformed vertebrae (e.g., hemivertebrae). Findings from the current study introduced descriptions of VVCD that can be used as background for future studies.

Artificial Selection Drives SNPs of Olfactory Receptor Genes into Different Working Traits in Labrador Retrievers

Labs as guide dogs or sniffer dogs in usage have been introduced into China for more than 20 years. These two types of working dogs own blunt or acute olfactory senses, which have been obtained by artificial selection in relatively closed populations. In order to attain stable olfactory attributes and meet use-oriented demands, Chinese breeders keep doing the same artificial selection. Though olfactory behavior is canine genetic behavior, genotypes of OR genes formed by breeding schemes are largely unknown. Here, we characterized 26 SNPs, 2 deletions, and 2 insertions of 7 OR genes between sniffer dogs and guide dogs in order to find out the candidate alleles associated with working specific traits. The results showed that there were candidate functional SNP alleles in one locus that had statistically severely significant differences between the two subpopulations. Furthermore, the levels of polymorphism were not high in all loci and linkage disequilibrium only happened within one OR gene. Hardy–Weinberg equilibrium (HWE) tests showed that there was a higher ratio not in HWE and lower FST within the two working dog populations. We conclude that artificial selection in working capacities has acted on SNP alleles of OR genes in a dog breed and driven the evolution in compliance with people's intentions though the changes are limited in decades of strategic breeding.

The effect of inbreeding, body size and morphology on health in dog breeds

Background

Dog breeds are known for their distinctive body shape, size, coat color, head type and behaviors, features that are relatively similar across members of a breed. Unfortunately, dog breeds are also characterized by distinct predispositions to disease. We explored the relationships between inbreeding, morphology and health using genotype based inbreeding estimates, body weight and insurance data for morbidity.

Results

The average inbreeding based on genotype across 227 breeds was F_adj = 0.249 (95% CI 0.235–0.263). There were significant differences in morbidity between breeds with low and high inbreeding (H = 16.49, P = 0.0004). There was also a significant difference in morbidity between brachycephalic breeds and non-brachycephalic breeds (P = 0.0048) and between functionally distinct groups of breeds (H = 14.95 P < 0.0001). Morbidity was modeled using robust regression analysis and both body weight (P < 0.0001) and inbreeding (P = 0.013) were significant (r² = 0.77). Smaller less inbred breeds were healthier than larger more inbred breeds.

Conclusions

In this study, body size and inbreeding along with deleterious morphologies contributed to increases in necessary health care in dogs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40575-021-00111-4.

Ophthalmic disorders in a referral population of seven breeds of brachycephalic dogs: 970 cases (2008-2017)

OBJECTIVE

To evaluate the frequency of ophthalmic disorders in 7 brachycephalic dog breeds referred to an academic veterinary ophthalmology service.

ANIMALS

970 client-owned dogs of 7 brachycephalic breeds that were evaluated by the ophthalmology service in a veterinary teaching hospital from January 2008 through December 2017.

PROCEDURES

Medical records of 7 brachycephalic breeds (ie, Boston Terriers, English Bulldogs, French Bulldogs, Lhasa Apsos, Pekingese, Pugs, and Shih Tzus) were reviewed to collect data regarding patient signalment, ophthalmic diagnoses, affected eyes, and number and dates of visits.

RESULTS

Median age at the first examination was 7 years (range, 23 days to 22 years). The number of dogs seen for a first examination increased with age. Corneal ulcers, keratoconjunctivitis sicca, corneal pigmentation, immature cataracts, and uveitis were each diagnosed in ≥ 100 dogs and represented 40.4% (1,161/2,873) of all diagnoses. On the basis of anatomic location, 66.3% (1,905/2,873) of all disorders were located in either the cornea (1,014/2,873 [35.2%]) or adnexa (891/2,873 [31%]). There was a significant difference in breed proportion in the study population; of the 7 breeds studied, Shih Tzus (34.3% [333/970]), Pugs (20.8% [202/970]), and Boston Terriers (16.6% [161/970]) were the most prevalent breeds. The frequency of some diseases within the referral population was associated with breed.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings suggested that the most prevalent disorders for the brachycephalic breeds in this ophthalmic referral population were corneal ulcers, keratoconjunctivitis sicca, corneal pigmentation, immature cataracts, and uveitis. Although all dogs shared brachycephalic features, the frequency of specific ophthalmic diseases varied between breeds.

An aggressive CD4- CD8- T-cell neoplasm in young English bulldogs

T-cell leukemia/lymphoma accounts for roughly 30% of all types of lymphoproliferative neoplasia in dogs. Two forms of T-cell lymphoma (T-zone and peripheral T-cell lymphoma) exhibit breed-specific predilections. During the course of routine immunophenotyping, we observed a breed-specific presentation of a unique form of T-cell leukaemia in young English bulldogs. To describe the clinical presentation and outcome of a novel T-cell leukaemia in English bulldogs and determine the frequency of this neoplasm in other breeds. The Clinical Hematopathology database, containing immunophenotyping data from peripheral blood of nearly 11 900 dogs, was queried for the phenotype observed in young English bulldogs: CD45⁺ CD4^- CD8^- CD5⁺ CD3⁺ class II major histocompatibility complex (MHC)-low T-cell leukaemia. Clinical presentation, treatment, and survival data were collected for a subset of cases. Fifty-five English bulldog cases and 64 cases of other breeds were identified. No other breed was represented by >5 cases. Complete medical records were obtained for 50 bulldogs. Median age at diagnosis was 3 years and 76% of cases were male. Median lymphocyte count was 44 286 lymphocytes/μl (range, 1800-317 684/μl) and lymphocytes were described as small to intermediate-sized. Many dogs were thrombocytopenic and had liver and spleen involvement, but not lymphadenopathy. Bulldogs that received multi-agent chemotherapy had longer median survival times (83 days) compared to dogs that received no treatment (6 days) or less aggressive therapy (15 days) (p = .001). Non-bulldogs had similar outcomes. CD4^- CD8^- class II MHC-low T-cell leukaemia has an aggressive clinical course and predilection for young English bulldogs. Breed-specific presentation suggests an underlying genetic cause.

Malassezia species dysbiosis in natural and allergen-induced atopic dermatitis in dogs

Malassezia dermatitis and otitis are recurrent features of canine atopic dermatitis, increasing the cost of care, and contributing to a reduced quality of life for the pet. The exact pathogenesis of secondary yeast infections in allergic dogs remains unclear, but some have proposed an overgrowth of M. pachydermatis to be one of the flare factors. The distribution of Malassezia populations on healthy and allergic canine skin has not been previously investigated using culture-independent methods. Skin swabs were collected from healthy, naturally affected allergic, and experimentally sensitized atopic dogs. From the extracted DNA, fungal next-generations sequencing (NGS) targeting the ITS region with phylogenetic analysis of sequences for species level classification, and Malassezia species-specific quantitative real-time polymerase chain reaction (qPCR) were performed. M. globosa was significantly more abundant on healthy canine skin by both methods (NGS P < .0001, qPCR P < .0001). M. restricta was significantly more abundant on healthy skin by NGS (P = .0023), and M. pachydermatis was significantly more abundant on naturally-affected allergic skin by NGS (P < .0001) and on allergen-induced atopic skin lesions by qPCR (P = .0015). Shifts in Malassezia populations were not observed in correlation with the development of allergen-induced skin lesions. Differences in the lipid dependency of predominant Malassezia commensals between groups suggests a role of the skin lipid content in driving community composition and raises questions of whether targeting skin lipids with therapeutics could promote healthy Malassezia populations on canine skin.

Dog leukocyte antigen (DLA) class II genotypes associated with chronic enteropathy in French bulldogs and miniature dachshunds

Canine chronic enteropathy (CE) is a group of immunogenetic disorders of unclear etiology characterized by chronic or recurrent gastrointestinal signs and inflammation. Diagnosis of CE subtypes by treatment response is a lengthy and challenging process, particularly in refractory cases of the disease. Given known association of dog leukocyte antigen (DLA) class II genotype and various immunogenetic disorders between and across breeds, this study was designed to examine the potential of determining susceptibility to refractory CE through identification of risk and protective genotypes in French bulldogs and miniature dachshunds-two popular dog breeds in Japan. Sequence-based genotyping of three DLA class II genes in 29 French bulldogs and 30 miniature dachshunds with refractory CE revealed a protective haplotype DLA-DRB1*002:01-DQA1*009:01-DQB1*001:01 against CE in French bulldogs (OR 0.09, 95 % CI 0.01-0.71, p = 0.0084). No statistical difference was noted between miniature dachshund cases and controls. These findings, largely disparate from a previous study on German shepherd dogs in the UK, were taken as possible indication of etiological differences in the refractory CE noted between and within breeds, and by extension, the potential of identifying such disease heterogeneity by DLA typing. The DLA-DQA1/DQB1 haplotype, protective against CE in our French bulldogs, has been reported as protective in various immune-mediated disorders such as Doberman hepatitis (Dyggve et al., 2011). Likewise, the DLA-DRB1*006:01 risk allele for Doberman hepatitis was noted in more French bulldogs with CE compared to controls, in line with reports on genotypes associated with both risk and protection being shared across various autoimmune diseases and breeds. These findings support an immunogenetic basis to the French bulldog-CE in our analysis, calling for further DLA studies working with larger samples and different breeds towards phenotypic clarification that may aid in early diagnosis, treatment, and prophylaxis through epigenetic approaches and breeding.

Thoracic Vertebral Canal Stenosis Associated with Vertebral Arch Anomalies in Small Brachycephalic Screw-Tail Dog Breeds

OBJECTIVE

 The aim of this study was to describe clinical and imaging features of thoracic vertebral canal stenosis secondary to the hypertrophy of the vertebral lamina and articular processes in screw-tail brachycephalic dog breeds, to evaluate the prevalence of the malformation in a large group of screw-tail dog breeds and to determine if degree of stenosis is associated with presence of neurological signs.

STUDY DESIGN

 This is a retrospective multicentric study.

MATERIALS AND METHODS

 Clinical records of 185 screw-tail brachycephalic dogs (French Bulldogs, English Bulldogs, Boston Terriers) and Pugs were reviewed. Ten dogs with neurological deficits secondary to thoracic vertebral canal stenosis diagnosed on magnetic resonance imaging were identified (Group 1). Neurologically normal dogs (n = 175) of the same breeds underwent computed tomographic imaging of the thoracic vertebral column for other medical reasons (Group 2). Cross-sectional measurements were used to calculate a stenotic ratio.

RESULTS

 Group 1 consisted of three French Bulldogs, six English Bulldogs and one Pug. Eight were males. Most dogs presented with progressive non-painful pelvic limbs ataxia and paresis. Twenty stenotic sites were identified with the most common being T4-T5. Three of ten dogs were treated surgically and all had a good long-term outcome. In Group 2, 33 of 175 dogs had one or more stenotic sites with the most common being T2-T3. The degree of the stenosis was significantly higher in Group 1 (p = 0.019). A stenotic ratio of 0.56 had sensitivity and specificity of 67% to differentiate between dogs with and without neurological signs.

CONCLUSION

 Cranial thoracic vertebral canal stenosis is observed predominantly in young male Bulldogs, but not all stenoses are clinically relevant.

Examination of the efficacy of small genetic panels in genomic conservation of companion animal populations

In many ways, dogs are an ideal model for the study of genetic erosion and population recovery, problems of major concern in the field of conservation genetics. Genetic diversity in many dog breeds has been declining systematically since the beginning of the 1800s, when modern breeding practices came into fashion. As such, inbreeding in domestic dog breeds is substantial and widespread and has led to an increase in recessive deleterious mutations of high effect as well as general inbreeding depression. Pedigrees can in theory be used to guide breeding decisions, though are often incomplete and do not reflect the full history of inbreeding. Small microsatellite panels are also used in some cases to choose mating pairs to produce litters with low levels of inbreeding. However, the long-term impact of such practices has not been thoroughly evaluated. Here, we use forward simulation on a model of the dog genome to examine the impact of using limited marker panels to guide pairwise mating decisions on genome-wide population-level genetic diversity. Our results suggest that in unmanaged populations, where breeding decisions are made at the pairwise-rather than population-level, such panels can lead to accelerated loss of genetic diversity at genome regions unlinked to panel markers, compared to random mating. These results demonstrate the importance of genome-wide genetic panels for managing and conserving genetic diversity in dogs and other companion animals.

The utility of DLA typing for transplantation medicine in canine models

Transplantation medicine is used for the treatment of severe canine diseases, and the dog leukocyte antigen (DLA) is considered to be important in graft rejection. However, the utility of direct sequencing of both DLA classes I and II has not been assessed thoroughly. Eight healthy beagles with identified DLA genes were divided into two sets of four dogs, each including one donor and three recipients for skin transplantation. The following recipients were selected: one dog with a complete match, one with a haploidentical match, and one with a complete mismatch of the DLA gene with the donor. Full-thickness skin segments were obtained from each donor and transplanted to the recipients. A mixed lymphocyte reaction (MLR) assay was performed and analyzed by flow cytometry. Skin grafts of DLA haploidentical and mismatched pairs were grossly rejected within 14 days, whereas in fully matched DLA pairs, survival was as long as 21 days. Histopathological evaluation also showed moderate to severe lymphocytic infiltration and necrosis in DLA mismatched pairs. As seen in the MLR assay, the stimulation index of DLA mismatched pairs was significantly higher than that of fully matched DLA pairs in both sets (P<0.001). The allogeneic transplantation results suggested that it is possible to prolong transplant engraftment by completely matching the DLA genotype between the donor and recipient. Additionally, the MLR assay may be used as a simplified in vitro method to select donors.

Moving from information and collaboration to action: report from the 4th international dog health workshop, Windsor in May 2019

Background

Dogs are the most popular mammal kept as a companion animal globally. Positive human-dog relationships can benefit both the human owners as well as the dogs. However, popularity as a companion animal species does not universally benefit dogs in reverse. Breed-related health problems in dogs have received increasing attention over the last decade, sparking increased concerns for dog welfare across many stakeholders. Progress towards improved welfare requires meaningful collaboration between all those working in dog health, science and welfare. The International Partnership for Dogs (IPFD), together with an alternating host organisation, holds biennial meetings called the International Dog Health Workshops (IDHW). The IPFD 4th IDHW was hosted by the UK Kennel Club in Windsor, UK in May 2019. With the aim of encouraging international and multi-stakeholder collaborations that are effective and ongoing, the 4th IDHW 2019 provided a forum to identify specific needs and actions that could improve health, well-being and welfare in dogs, building on outcomes and evaluating actions of previous IDHWs.

Results

The workshop included 126 decision-leaders from 16 countries and was structured around five key themes identified as needing international, multi-stakeholder attention. These included the concept of “breed”, supply and demand, breed-specific strategies for health and breeding, genetic testing and extreme conformations. The review of progress made since the 3rd IDHW 2017 and the comprehensive lists of actions agreed upon during the current meeting suggest that movement from information and collaboration to action has been achieved. Working groups with specific tasks were identified and many plan to continue to communicate through forum communities on DogWellNet.com.

Conclusions

The IDHW provides a forum for formal and informal discussion between relevant groups so that key dog health and welfare issues can be identified and defined, and plans can be agreed for effective actions to address them. The 3rd IDHW 2017 resulted in a number of significant outcomes. New and continuing actions were laid down at the 4th IDHW 2019, which will be re-evaluated at the 5th IDHW facilitating continual progress.

The German Shorthair Pointer Dog Breed (Canis lupus familiaris): Genomic Inbreeding and Variability

The German Shorthaired Pointer (GSHP) is a breed worldwide known for its hunting versatility. Dogs of this breed are appreciated as valuable companions, effective trackers, field trailers and obedience athletes. The aim of the present work is to describe the genomic architecture of the GSHP breed and to analyze inbreeding levels under a genomic and a genealogic perspective. A total of 34 samples were collected (24 Italian, 10 USA), and the genomic and pedigree coefficients of inbreeding have been calculated. A total of 3183 runs of homozygosity (ROH) across all 34 dogs have been identified. The minimum and maximum number of Single Nucleotide Polymorphisms (SNPs) defining all ROH are 40 and 3060. The mean number of ROH for the sample was 93.6. ROH were found on all chromosomes. A total of 854 SNPs (TOP_SNPs) defined 11 ROH island regions (TOP_ROH), in which some gene already associated with behavioral and morphological canine traits was annotated. The proportion of averaged observed homozygotes estimated on total number of SNPs was 0.70. The genomic inbreeding coefficient based on ROH was 0.17. The mean inbreeding based on genealogical information resulted 0.023. The results describe a low inbred population with quite a good level of genetic variability.

A retrospective survey on canine intracranial tumors between 2007 and 2017

To clarify the prevalence of canine intracranial tumors in Japan, a retrospective study was performed using data on 186 canine intracranial tumors. Of 186 cases, 159 cases (85.5%) were primary and 27 cases (14.5%) were secondary intracranial tumors. Among primary intracranial tumors, meningioma (50.9%) was the most common, followed by glial tumors (21.4%) and primary intracranial histiocytic sarcoma (12.6%). These 3 tumors were most frequently found in middle-aged to elderly dogs without any sex predilection. Regarding glial tumors, the incidence of oligodendroglial tumors (79.4%) was higher than that of astrocytic tumors (17.6%). A significant breed predisposition (P<0.05) was observed for meningioma in Rough Collie, Golden Retriever, Miniature Schnauzer, and Scottish Terrier; for glial tumors in Bouvier de Flandres, French Bulldog, Newfoundland, Bulldog, and Boxer; for primary intracranial histiocytic sarcoma in Pembroke Welsh Corgi, Siberian Husky, and Miniature Schnauzer. The high incidence of oligodendroglial tumors in dogs and the breed predisposition for primary intracranial histiocytic sarcoma in Pembroke Welsh Corgi have not been reported in previous epidemiological studies on canine tumors. Since the incidence of intracranial tumors was vary among dog breeds, the present results demonstrate the uniqueness of the canine breed population in Japan.

Breeding French bulldogs so that they breathe well-A long way to go

Brachycephalic syndrome (BS) is a pathophysiological disorder caused by excessive soft tissue within the upper airways of short-nosed dog breeds, causing obstruction of the nasal, pharyngeal and laryngeal lumen, resulting in severe respiratory distress. As the prevalence of BS appears to be high among some of the affected breeds, there is an urgent need for breeding efforts to improve the health status of those dogs. In the present study, we evaluated correlations between morphometric and other phenotypic characteristics and BS in a population of 69 French bulldogs from Denmark to identify parameters that could serve as a basis for breeding against BS. Furthermore, the genetic variation was monitored to determine whether it would be possible to breed based on these characteristics without simultaneously causing a critical reduction in genetic variation. Six phenotypic characteristics were correlated with the Brachycephalic Syndrome Functional (BSF) score. Among the morphometric risk factors, nostril stenosis (NS) and neck girth (NG) had the highest impact on the BSF score, accounting for 32% and 4% of the variation, respectively. The genetic variation in the population was comparable to other pure breeds, i.e. estimated and observed heterozygosity was 0.60 and the average inbreeding coefficient was 0.01. If only dogs with Grades 1 and 2 NS (no or only mild NS) were selected for breeding the mean BSF score would be reduced significantly. However, it would result in the exclusion of 81% of the population for breeding and this is not prudent. Excluding only dogs with severe stenosis (Grade 4) would exclude 50% of the population without any adverse impact on genetic variation within the population. Although exclusion of dogs with Grade 4 would result in an apparent reduction in the mean BSF score, this reduction is not significant. As NS accounts for 32% of the variation in BSF score, a possible long term strategy to reduce the prevalence of the BS in French bulldogs would seem to be a selection scheme that first excluded dogs with the most severe NS from breeding, gradually moving towards selecting dogs with lower NS grades. According to our findings there is no viable short term solution for reducing the prevalence of BS in the French bulldog population.

Congenital lung displacement in an English bulldog puppy

The English bulldog is notoriously predisposed to a number of disease conditions, including congenital defects, likely due to extreme genetic selection which has reduced genetic variability within this breed. The present report describes, for the first time, the main clinical and pathological features of congenital lung displacement in an English bulldog puppy. The defect involved the entire left lung, which was normally developed but rotated and shifted to the right hemithorax. The pathogenesis of congenital anomalies is largely unknown. characterisation of the genetic bases of these malformations is crucial for a reform of the breeding selection which is also aimed at correcting phenotypic abnormalities with a strong impact on individual health.

True Colors: Commercially-acquired morphological genotypes reveal hidden allele variation among dog breeds, informing both trait ancestry and breed potential

Direct-to-consumer canine genetic testing is becoming increasingly popular among dog owners. The data collected therein provides intriguing insight into the current status of morphological variation present within purebred populations. Mars WISDOM PANELTM data from 11,790 anonymized dogs, representing 212 breeds and 4 wild canine species, were evaluated at genes associated with 7 coat color traits and 5 physical characteristics. Frequencies for all tested alleles at these 12 genes were determined by breed and by phylogenetic grouping. A sub-set of the data, consisting of 30 breeds, was divided into separate same-breed populations based on country of collection, body size, coat variation, or lineages selected for working or conformation traits. Significantly different (p ≤ 0.00167) allele frequencies were observed between populations for at least one of the tested genes in 26 of the 30 breeds. Next, standard breed descriptions from major American and international registries were used to determine colors and tail lengths (e.g. genetic bobtail) accepted within each breed. Alleles capable of producing traits incongruous with breed descriptions were observed in 143 breeds, such that random mating within breeds has probabilities of between 4.9e-7 and 0.25 of creating undesirable phenotypes. Finally, the presence of rare alleles within breeds, such as those for the recessive black coloration and natural bobtail, was combined with previously published identity-by-decent haplotype sharing levels to propose pathways by which the alleles may have spread throughout dog breeds. Taken together, this work demonstrates that: 1) the occurrence of low frequency alleles within breeds can reveal the influence of regional or functional selection practices; 2) it is possible to visualize the potential historic connections between breeds that share rare alleles; and 3) the necessity of addressing conflicting ideals in breed descriptions relative to actual genetic potential is crucial.

Factors influencing English Bulldog bitch fertility after surgical uterine deposition of fresh semen

The aim of this study was to evaluate the effect of body weight, oxytocin deposition in the uterus at artificial insemination (AI), vaginal cytology, serum progesterone (P₄) concentration at AI, semen volume and total sperm cells per AI on whelping rate and litter size of English Bulldogs bitches following intrauterine surgical semen deposition. Seventy-eight English Bulldog bitches were artificially inseminated via semen infusion (number of sperm cells inseminated 300-2500 × 10⁶) at the uterine body with fresh semen without extender and under general anesthesia. Whelping rate was greater (P < 0.05) in bitches with >23 kg than bitches with <23 kg (83.9 vs 63.8%). Whelping rate was greater (P < 0.01) in bitches with >75% vaginal cornified epithelium at AI (85.1%) than animals with <75% cornified epithelium (51.6%). Whelping rates were influenced (P < 0.01) by the semen volume at AI (54.3% vs 86.1% for bitches receiving <4 mL or >4 mL of semen). Litter size was larger (P < 0.05) in bitches >23 kg than lighter animals (3.72 ± 1.79 and 2.30 ± 1.46 pups per litter, respectively). Litter size was not influenced by sperm concentration, semen volume, vaginal cytology, serum P₄ concentration and infusion of oxytocin in the uterus at AI (P > 0.1). The results of this study indicate that increasing body weight of English Bulldog bitches is related to higher whelping rates and larger litter size. Also, >75% of superficial cornified vaginal cells (squamous) at AI and >4 mL semen volume maximize whelping rates in this breed of dogs.

Maladaptation in feral and domesticated animals

Selection regimes and population structures can be powerfully changed by domestication and feralization, and these changes can modulate animal fitness in both captive and natural environments. In this review, we synthesize recent studies of these two processes and consider their impacts on organismal and population fitness. Domestication and feralization offer multiple windows into the forms and mechanisms of maladaptation. Firstly, domestic and feral organisms that exhibit suboptimal traits or fitness allow us to identify their underlying causes within tractable research systems. This has facilitated significant progress in our general understandings of genotype-phenotype relationships, fitness trade-offs, and the roles of population structure and artificial selection in shaping domestic and formerly domestic organisms. Additionally, feralization of artificially selected gene variants and organisms can reveal or produce maladaptation in other inhabitants of an invaded biotic community. In these instances, feral animals often show similar fitness advantages to other invasive species, but they are also unique in their capacities to modify natural ecosystems through introductions of artificially selected traits. We conclude with a brief consideration of how emerging technologies such as genome editing could change the tempos, trajectories, and ecological consequences of both domestication and feralization. In addition to providing basic evolutionary insights, our growing understanding of mechanisms through which artificial selection can modulate fitness has diverse and important applications-from enhancing the welfare, sustainability, and efficiency of agroindustry, to mitigating biotic invasions.

Skin and ear health in a group of English bulldogs in Finland - a descriptive study with special reference to owner perceptions

Background

Dermatological conditions are common in English bulldogs (EBs).

Hypothesis/Objectives

This cross‐sectional study describes the dermatological health status of a group of EBs and compares the results with owner perceptions and its possible impact on quality of life (QoL). Computed tomographic (CT) findings of the ear canals were compared between EBs and mesaticephalic dogs.

Animals

Twenty‐seven EBs participating in a health study in Finland.

Methods and materials

A QoL questionnaire was completed for EBs with owner‐reported clinical signs referable to the skin or ear. Clinical evaluation included recording the Canine Atopic Dermatitis Extent and Severity Index, the Otitis Index Score, false paw pad grading and the presence of interdigital furunculosis. These were summed to form a total clinical score (TCS). The cross‐sectional surface areas of the horizontal ear canals were measured from CT images and compared with respective images of 14 mesaticephalic dogs collected from a patient database.

Results

All 27 EBs had abnormal findings on dermatological examination, but 37% of the owners had not recognized skin or ear signs. The median QoL score was 5.0 (range 0–12) and correlated with TCS (correlation coefficient = 0.507, P < 0.05). English bulldogs had narrower horizontal ear canals than mesaticephalic dogs (P < 0.001).

Conclusions and clinical importance

All EBs had abnormal dermatological findings that were unnoticed or considered to be of minor significance to the QoL by most owners. Narrow ear canals were common, possibly related to the brachycephalic conformation of the breed.

Genetic heterogeneity and diversity of North American golden retrievers using a low density STR marker panel

Thirty-three autosomal short tandem repeat (STR) markers were used to evaluate genetic heterogeneity and diversity in 525 golden retrievers (GRs). This breed was selected because of its popularity and artificial selection for conformation vs. performance phenotypes. Seven additional STRs were used to evaluate the highly polymorphic dog leukocyte antigen (DLA) class I and class II regions. From 3 to 13 alleles were found at each of the 33 loci (mean 7) and the average effective alleles (Ne) was 3.34. The observed heterozygosity was 0.65 and the expected heterozygosity was 0.68. The resulting fixation index was 0.035 indicating that the population was randomly breeding. We found that modern GRs retain 46% of genomic diversity present in all canids and 21/175 (12%) and 20/90 (22%) of the known DLA class I and class II haplotypes, respectively. Selection for performance or conformation led to a narrowing of genomic and DLA diversity with conformation having a greater effect than performance. A comparison was made between coefficient of inbreeding (COI) determined from 10 or 12 generation pedigrees and DNA based internal relatedness values. A weak but significant correlation was observed between IR score and 10 or 12 generation COI (r = 0.38, p<0.0001 and r = 0.40, p<0.0001, respectively). IR values were higher in conformation than performance lines but only significant at p = 0.17. This was supported by 10 and 12 generation COI values that were significantly (p<0.0001) higher in conformation than performance lines. We demonstrate herein that a low density of STR markers can be utilized to study the genetic makeup of GRs.

Polymorphism analyses of 19 STRs in Labrador Retriever population from China and its heterozygosity comparisons with other retriever breeds

Pure breed dogs of Western origin are increasingly more popular in China as is a need to differentiate breeds and individual dogs for personal and forensic reasons. Research on genetic diversities of the canine population in China is rarely conducted. In this study, genetic distributions and forensic efficiencies of 19 canine STR loci in Labrador Retriever population from China were evaluated by using one available commercial canine kit in China. This panel was used to genetically define 214 Labrador Retrievers in China, as an example of one of the most important Western breeds and to compare them with Labrador Retrievers from America based on three overlapping STR loci. Moreover, genetic relationship analyses between Labrador Retriever population and two reference populations in America were performed. All 19 STR loci were polymorphic and conformed to Hardy-Weinberg equilibrium in the studied population. The STR panel was able to discern individual dogs with a high degree of accuracy. Breed-wide genetic heterozygosity comparisons based on present and published allele frequencies revealed that the studied population had the lower genetic heterozygosity than canine populations in America. Principal component analysis among Labrador Retriever population and other reference populations showed that the studied Labrador Retrievers were genetically close to the retriever breeds in America. Population genetic structure analyses among these canine breeds further revealed genetic differentiations between the studied Labrador Retriever population and other compared breeds. In conclusion, these STR loci had relatively high forensic values in Labrador Retriever population in China, which could be employed for individual identification and kinship testing.

Fine-Scale Resolution of Runs of Homozygosity Reveal Patterns of Inbreeding and Substantial Overlap with Recessive Disease Genotypes in Domestic Dogs

Inbreeding leaves distinct genomic traces, most notably long genomic tracts that are identical by descent and completely homozygous. These runs of homozygosity (ROH) can contribute to inbreeding depression if they contain deleterious variants that are fully or partially recessive. Several lines of evidence have been used to show that long (> 5 megabase) ROH are disproportionately likely to harbor deleterious variation, but the extent to which long vs. short tracts contribute to autozygosity at loci known to be deleterious and recessive has not been studied. In domestic dogs, nearly 200 mutations are known to cause recessive diseases, most of which can be efficiently assayed using SNP arrays. By examining genome-wide data from over 200,000 markers, including 150 recessive disease variants, we built high-resolution ROH density maps for nearly 2,500 dogs, recording ROH down to 500 kilobases. We observed over 678 homozygous deleterious recessive genotypes in the panel across 29 loci, 90% of which overlapped with ROH inferred by GERMLINE. Although most of these genotypes were contained in ROH over 5 Mb in length, 14% were contained in short (0.5 - 2.5 megabase) tracts, a significant enrichment compared to the genetic background, suggesting that even short tracts are useful for computing inbreeding metrics like the coefficient of inbreeding estimated from ROH (F_ROH ). In our dataset, F_ROH differed significantly both within and among dog breeds. All breeds harbored some regions of reduced genetic diversity due to drift or selective sweeps, but the degree of inbreeding and the proportion of inbreeding caused by short vs. long tracts differed between breeds, reflecting their different population histories. Although only available for a few species, large genome-wide datasets including recessive disease variants hold particular promise not only for disentangling the genetic architecture of inbreeding depression, but also evaluating and improving upon current approaches for detecting ROH.

Consequences and Management of Canine Brachycephaly in Veterinary Practice: Perspectives from Australian Veterinarians and Veterinary Specialists

This article, written by veterinarians whose caseloads include brachycephalic dogs, argues that there is now widespread evidence documenting a link between extreme brachycephalic phenotypes and chronic disease, which compromises canine welfare. This paper is divided into nine sections exploring the breadth of the impact of brachycephaly on the incidence of disease, as indicated by pet insurance claims data from an Australian pet insurance provider, the stabilization of respiratory distress associated with brachycephalic obstructive airway syndrome (BOAS), challenges associated with sedation and the anaesthesia of patients with BOAS; effects of brachycephaly on the brain and associated neurological conditions, dermatological conditions associated with brachycephalic breeds, and other conditions, including ophthalmic and orthopedic conditions, and behavioural consequences of brachycephaly. In the light of this information, we discuss the ethical challenges that are associated with brachycephalic breeds, and the role of the veterinarian. In summary, dogs with BOAS do not enjoy freedom from discomfort, nor freedom from pain, injury, and disease, and they do not enjoy the freedom to express normal behaviour. According to both deontological and utilitarian ethical frameworks, the breeding of dogs with BOAS cannot be justified, and further, cannot be recommended, and indeed, should be discouraged by veterinarians.

Novel association of Psychrobacter and Pseudomonas with malodour in bloodhound dogs, and the effects of a topical product composed of essential oils and plant-derived essential fatty acids in a randomized, blinded, placebo-controlled study

BACKGROUND

The pathogenesis and treatment of cutaneous malodour in dogs have not been investigated previously. Staphylococcus and Corynebacterium spp. are associated with human axillary malodour.

HYPOTHESIS

Staphylococcus and Corynebacterium spp. are associated with cutaneous malodour in dogs, and treatment with a topical essential oil-based product will improve malodour and reduce the abundance of odour-causing bacteria.

ANIMALS

Twenty seven bloodhound dogs from a south Texas boarding facility were enrolled in this study.

METHODS AND MATERIALS

Skin swabs were taken from the axilla and dorsum of 27 dogs at initiation of the study. Mean malodour scores were used to assign dogs to control or malodour groups. The malodourous dogs were randomly assigned to a treatment or placebo group, received four weekly topical applications of the spot-on or placebo, and samples were recollected. Next-generation sequencing (NGS) and real-time quantitative PCR (qPCR) were performed on all swabs.

RESULTS

Psychrobacter and Pseudomonas spp. were significantly more abundant (P < 0.001, P = 0.006; respectively), and overall bacterial diversity was reduced (P = 0.0384) on the skin of malodourous dogs. Staphylococcus and Corynebacterium spp. were not associated with malodour. The topical essential oil-based product significantly (P = 0.0078) improved malodour in the treatment group and shifted their bacterial community structure.

CONCLUSIONS AND CLINICAL IMPORTANCE

A novel association of bacterial genera with malodour in bloodhound dogs, identified by NGS, highlights future targets for odour control. The topical treatment significantly reduced malodour. The interaction between the topical treatment and cutaneous microbiota should be further investigated and may be useful in other dermatological conditions involving microbiota.

A cross-sectional study of show English bulldogs in the United States: evaluating paw lesions, cytological findings, pruritic behaviours and gastrointestinal signs

BACKGROUND

English bulldogs (EBDs) are considered to commonly show signs of pododermatitis and gastrointestinal (GI) disease.

HYPOTHESIS/OBJECTIVES

To describe a population of presumed healthy EBDs: (i) evaluate dogs according to published criteria for health, (ii) describe paw lesions, if present, (iii) report pruritic behaviours and GI signs and compare to normal values, (iv) report pedal cytological findings, and (v) determine correlation between lesions, cytological results and pruritic behaviours.

ANIMALS

Thirty four EBDs participating in a dog show.

METHODS AND MATERIALS

Dogs were examined, and pedal cytological samples were collected. Pruritic behaviours, GI signs and medical history were assessed. Owners completed questionnaires regarding history and assessed pruritus.

RESULTS

No dog met criteria for being healthy. All dogs had an abnormal dermatological examination, 22 of 34 had a history of recent drug administration and 16 of 34 had a history of dermatological disease. Every dog had at least one erythematous paw. Compared to values for a healthy dog population, facial rubbing was the only increased pruritic behaviour, and GI signs differed in belching, flatulence and regurgitation. Mean cytological evaluation values were within normal ranges except for inflammation. Lesions did not correlate with cytological findings or pruritic behaviours, with the exception of white coloured exudation with inflammation and cocci.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study supports that show EBDs have frequent pedal lesions and history of dermatological disease, with over half receiving medication, as well as increased frequency of belching, flatulence and facial rubbing. Pedal cytological findings were not predictive of lesions, with the exception of white coloured exudation.

Weighted likelihood inference of genomic autozygosity patterns in dense genotype data

Background

Genomic regions of autozygosity (ROA) arise when an individual is homozygous for haplotypes inherited identical-by-descent from ancestors shared by both parents. Over the past decade, they have gained importance for understanding evolutionary history and the genetic basis of complex diseases and traits. However, methods to infer ROA in dense genotype data have not evolved in step with advances in genome technology that now enable us to rapidly create large high-resolution genotype datasets, limiting our ability to investigate their constituent ROA patterns.

Methods

We report a weighted likelihood approach for inferring ROA in dense genotype data that accounts for autocorrelation among genotyped positions and the possibilities of unobserved mutation and recombination events, and variability in the confidence of individual genotype calls in whole genome sequence (WGS) data.

Results

Forward-time genetic simulations under two demographic scenarios that reflect situations where inbreeding and its effect on fitness are of interest suggest this approach is better powered than existing state-of-the-art methods to infer ROA at marker densities consistent with WGS and popular microarray genotyping platforms used in human and non-human studies. Moreover, we present evidence that suggests this approach is able to distinguish ROA arising via consanguinity from ROA arising via endogamy. Using subsets of The 1000 Genomes Project Phase 3 data we show that, relative to WGS, intermediate and long ROA are captured robustly with popular microarray platforms, while detection of short ROA is more variable and improves with marker density. Worldwide ROA patterns inferred from WGS data are found to accord well with those previously reported on the basis of microarray genotype data. Finally, we highlight the potential of this approach to detect genomic regions enriched for autozygosity signals in one group relative to another based upon comparisons of per-individual autozygosity likelihoods instead of inferred ROA frequencies.

Conclusions

This weighted likelihood ROA inference approach can assist population- and disease-geneticists working with a wide variety of data types and species to explore ROA patterns and to identify genomic regions with differential ROA signals among groups, thereby advancing our understanding of evolutionary history and the role of recessive variation in phenotypic variation and disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-4312-3) contains supplementary material, which is available to authorized users.

An autosomal recessive mutation in SCL24A4 causing enamel hypoplasia in Samoyed and its relationship to breed-wide genetic diversity

Background

Pure breeding of dogs has led to over 700 heritable disorders, of which almost 300 are Mendelian in nature. Seventy percent of the characterized mutations have an autosomal recessive mode of inheritance, indicative of positive selection during bouts of inbreeding primarily for new desired conformational traits. Samoyed suffer from several common complex genetic disorders, but up to this time only two X-linked and one autosomal dominant disorder have been identified. Previous studies based on pedigrees and SNP arrays have concluded that Samoyed breeders have done a good job in maintaining genetic diversity and avoiding excessive inbreeding. This may explain why autosomal recessive disorders have not occurred to the extent observed in many other breeds. However, an enamel hypoplasia analogous to a form of autosomal recessive amelogenesis imperfecta (ARAI) in humans has been recently characterized in Samoyed, although the causative mutation appears to have existed for three or more decades. The rise of such a mutation indicates that bouts of inbreeding for desired conformational traits are still occurring despite an old and well-defined breed standard. Therefore, the present study has two objectives: 1) measure genetic diversity in the breed using DNA and short tandem repeats (STR), and 2) identify the exact mutation responsible for enamel hypoplasia in the breed, possible explanations for its recent spread, and the effect of eliminating the mutation on existing genetic diversity.

Results

The recent discovery of an autosomal recessive amelogenesis imperfecta (ARAI) in Samoyed provides an opportunity to study the mutation as well as genetic factors that favored its occurrence and subsequent spread. The first step in the study was to use 33 short tandem repeat (STR) loci on 25/38 autosomes and seven STRs across the dog leukocyte antigen (DLA) class I and II regions on CFA12 to determine the DNA-based genetic profile of 182 individuals from North America, Europe and Australia. Samoyed from the three continents constituted a single breed with only slight genetic differences. Breed-wide genetic diversity was low, most likely from a small founder population and subsequent artificial genetic bottlenecks. Two alleles at each autosome locus occurred in 70–95% of the dogs and 54% of alleles were homozygous. The number of DLA class I and II haplotypes was also low and three class I and two class II haplotypes occurred in 80–90% of individuals. Therefore, most Samoyed belong to two lines, with most dogs possessing a minority of existing genetic diversity and a minority of dogs containing a majority of diversity. Although contemporary Samoyed lack genetic diversity, the bulk of parents are as unrelated as possible with smaller subpopulations either more inbred or outbred than the total population. A familial disorder manifested by hypocalcification of enamel has been recently identified. A genome wide association study (GWAS) on seven affected and five unrelated healthy dogs pointed to a region of extended homozygosity on Canis familiaris autosome 8 (CFA8). The region contained a gene in the solute carrier 24 family (SCL24A4) that encodes a protein involved in potassium dependent sodium/calcium exchange and transport. Mutations in this gene were recently found to cause a similar type of enamel hypoplasia in people. Sequencing of this candidate gene revealed a 21 bp duplication in exon 17. A test for the duplication was in concordance with the disease phenotype. The exact incidence of affected dogs is unknown, but 12% of the 168 healthy dogs tested were heterozygous for the mutation. This population was biased toward close relatives, so a liberal estimate of the incidence of affected dogs in the breed would be around 3.6/1000. Theoretical calculations based on the comparison of the whole population with a population devoid of carriers indicated that eliminating the trait would not affect existing genetic diversity at this time.

Conclusions

The contemporary Samoyed, like many other breeds, has retained only a small portion of the genetic diversity that exists among all dogs. This limited genetic diversity along with positive genetic selection for desirable traits has led to at least three simple non-recessive genetic disorders and a low incidence of complex genetic traits such as autoimmune disease and hip dysplasia. Unlike many other pure breeds, the Samoyed has been spared the spate of deleterious autosomal recessive traits that have plagued many other pure breeds. However, ARAI due to a mutation in the SCL24A4 gene has apparently existed in the breed for several decades but is being increasingly diagnosed. The increase in diseased dogs is most likely due to a period of intensified positive selection for some desired conformational trait. A genetic test has been developed for identifying the mutation carriers which will enable the breeders to eliminate enamel hypoplasia in Samoyed by selective breeding and it appears that this mutation can be eliminated now without loss of genetic diversity.