Association analysis between canine behavioural traits and genetic polymorphisms in the Shiba Inu breed

Carrier Rate and Mutant Allele Frequency of GM1 Gangliosidosis in Miniature Shiba Inus (Mame Shiba): Population Screening of Breeding Dogs in Japan

GM1 gangliosidosis is a progressive, recessive, autosomal, neurodegenerative, lysosomal storage disorder that affects the brain and multiple systemic organs due to an acid β-galactosidase deficiency encoded by the GLB1 gene. This disease occurs in the Shiba Inu breed, which is one of the most popular traditional breeds in Japan, due to the GLB1:c.1649delC (p.P550Rfs*50) mutation. Previous surveys performed of the Shiba Inu population in Japan found a carrier rate of 1.02–2.94%. Currently, a miniature type of the Shiba Inu called “Mame Shiba”, bred via artificial selection to yield smaller individuals, is becoming more popular than the standard Shiba Inu and it is now one of the most popular breeds in Japan and China. The GM1 gangliosidosis mutation has yet to be surveyed in the Mame Shiba population. This study aimed to determine the frequency of the mutant allele and carrier rate of GM1 gangliosidosis in the Mame Shiba breed. Blood samples were collected from 1832 clinically healthy adult Mame Shiba Inus used for breeding across 143 Japanese kennels. The genotyping was performed using a real-time PCR assay. The survey found nine carriers among the Mame Shibas, indicating that the carrier rate and mutant allele frequency were 0.49% and 0.00246, respectively. This study demonstrated that the mutant allele has already been inherited by the Mame Shiba population. There is a risk of GM1 gangliosidosis occurrence in the Mame Shiba breed if breeders use carriers for mating. Further genotyping surveys are necessary for breeding Mame Shibas to prevent the inheritance of this disease.

Raising an Assistance Dog Puppy-Stakeholder Perspectives on What Helps and What Hinders

Simple Summary

Puppy raisers (or foster families) are volunteers who care for assistance dog puppies until they are ready to learn how to help people with a disability. During this period, some puppies develop behaviours unsuitable for assistance roles and end up changing careers or being rehomed as pets, which is wasteful. Puppy raisers control the early experiences of their puppies, and they vary in their puppy-raising outcomes, but we do not know what specifically helps some puppy raisers produce puppies that are behaviourally suitable for an assistance role. In this study, we interviewed 17 people from seven countries who were either experienced puppy raisers or provider program staff, or both. Their responses suggested several individual factors (expectations, competency, perseverance and passion) and social factors (informational and emotional supports), in addition to the puppies’ characteristics, that influenced the experiences and perceived effectiveness of their puppy-raising practices. These factors are also evident in other well-established areas of research (e.g., education, volunteerism, social support, and organisational performance). We propose recommendations for assistance dog organisations based on those relevant frameworks, which focus on enhancing puppy raisers’ competency, positive experiences, and program retention.

Abstract

Assistance dog puppies live with their raisers for up to 16 months before entering advanced training and, hopefully, becoming qualified to help people with a disability. Almost half of the puppies fail to meet the behavioural standards required for assistance dogs, and some puppy raisers produce more behaviourally favourable puppies than others. It is unclear what factors influence puppy-raising practice quality. To understand this, we interviewed 17 participants, including experienced puppy raisers (n = 8), provider organisation staff (n = 4), and those who have served both as puppy raisers and staff (n = 5). Results of a thematic analysis suggest three groups of influencing factors, namely intrapersonal factors, social support, and puppy characteristics. Intrapersonal factors such as expectations, competency, perseverance and passion were reported to influence puppy raisers’ experiences, puppy-raising quality, and continuity of service. Contextual factors such as availability of social support (informational and emotional supports) and less-demanding puppies both led to positive puppy-raising experiences, while the former also contributed to puppy raisers’ perceptions of competency. Future research should quantitatively examine the interrelationships of these factors concerning puppies’ behavioural development. Meanwhile, organisations could consider these factors when developing their recruitment and puppy-raiser support programs.

Analysis of new retrogenes provides insight into dog adaptive evolution

The origin and subsequent evolution of new genes have been considered as an important source of genetic and phenotypic diversity in organisms. Dog breeds show great phenotypic diversity for morphological, physiological, and behavioral traits. However, the contributions of newly originated retrogenes, which provide important genetic bases for dog species differentiation and adaptive traits, are largely unknown. Here, we analyzed the dog genome to identify new RNA-based duplications and comprehensively investigated their origin, evolution, functions in adaptive traits, and gene movement processes. First, we totally identified 3,025 retrocopies including 476 intact retrogenes, 2,518 retropseudogenes, and 31 chimerical retrogenes. Second, selective pressure along with ESTs expression analysis showed that most of the intact retrogenes were significantly under stronger purifying selection and subjected to more functional constraints when compared to retropseudogenes. Furthermore, a large number of retrocopies and chimerical retrogenes that occurred approximately 22 million years ago implied a burst of retrotransposition in the dog genome after the divergence time between dog and its closely related species red fox. Interestingly, GO and pathway analyses showed that new retrogenes had expanded in glutathione biosynthetic/metabolic process which likely provided important genetic basis for dogs' adaptation to scavenge human waste dumps. Finally, consistent with the results in human and mouse, a significant excess of functional retrogenes movement on and off the X chromosome in the dog confirmed a general pattern of gene movement process in mammals which was likely driven by natural selection or sexual antagonism. Together, these results increase our understanding that new retrogenes can reshape the dog genome and provide further exploration of the molecular mechanisms underlying the dogs' adaptive evolution.

Polymorphisms in the canine monoamine oxidase a (MAOA) gene: identification and variation among five broad dog breed groups

BACKGROUND

In humans, reduced activity of the enzyme monoamine oxidase type A (MAOA) due to genetic polymorphisms within the MAOA gene leads to increased brain neurotransmitter levels associated with aggression. In order to study MAOA genetic diversity in dogs, we designed a preliminary study whose objectives were to identify novel alleles in functionally important regions of the canine MAOA gene, and to investigate whether the frequencies of these polymorphisms varied between five broad breed groups (ancient, herding, mastiff, modern European, and mountain). Fifty dogs representing these five breed groups were sequenced.

RESULTS

A total of eleven polymorphisms were found. Seven were single nucleotide polymorphisms (SNPs; two exonic, two intronic and three in the promoter), while four were repeat intronic variations. The most polymorphic loci were repeat regions in introns 1, 2 (7 alleles) and 10 (3 alleles), while the exonic and the promoter regions were highly conserved. Comparison of the allele frequencies of certain microsatellite polymorphisms among the breed groups indicated a decreasing or increasing trend in the number of repeats at different microsatellite loci, as well as the highest genetic diversity for the ancient breeds and the lowest for the most recent mountain breeds, perhaps attributable to canine domestication and recent breed formation. While a specific promoter SNP (-212A > G) is rare in the dog, it is the major allele in wolves. Replacement of this ancestral allele in domestic dogs may lead to the deletion of heat shock factor binding sites on the MAOA promoter.

CONCLUSIONS

Dogs exhibit significant variation in certain intronic regions of the MAOA gene, while the coding and promoter regions are well-conserved. Distinct genetic differences were observed between breed groups. Further studies are now required to establish whether such polymorphisms are associated in any way with MAOA level and canine behaviour including aggression.

"Reactivity to stimuli" is a temperamental factor contributing to canine aggression

Canine aggression is one of the most frequent problems in veterinary behavioral medicine, which in severe cases may result in relinquishment or euthanasia. As it is important to reveal underlying factors of aggression for both treatment and prevention, we recently developed a questionnaire on aggression and temperamental traits and found that “reactivity to stimuli” was associated with aggression toward owners, children, strangers, and other dogs of the Shiba Inu breed. In order to examine whether these associations were consistent in other breeds, we asked the owners of insured dogs of Anicom Insurance Inc. to complete our questionnaire. The top 17 contracted breeds were included. The questionnaire consisted of dogs' general information, four items related to aggression toward owners, children, strangers, and other dogs, and 20 other behavioral items. Aggression-related and behavioral items were rated on a five-point frequency scale. Valid responses (n = 5610) from owners of dogs aged 1 through 10 years were collected. Factor analyses on 18 behavioral items (response rate over 95%) extracted five largely consistent factors in 14 breeds: “sociability with humans,” “fear of sounds,” “chase proneness,” “reactivity to stimuli,” and “avoidance of aversive events.” By stepwise multiple regression analyses, using the Schwartz's Bayesian information criterion (BIC) method with aggression points as objective variables and general information and temperamental factor points as explanatory variables, “reactivity to stimuli,” i.e., physical reactivity to sudden movement or sound at home, was shown to be significantly associated with owner-directed aggression in 13 breeds, child-directed aggression in eight breeds, stranger-directed aggression in nine breeds, and dog-directed aggression in five breeds. These results suggest that “reactivity to stimuli” is simultaneously involved in several types of aggression. Therefore, it would be worth taking “reactivity to stimuli” into account in the treatment and prevention of canine aggression.

Holding back the genes: limitations of research into canine behavioural genetics

Canine behaviours that are both desirable and undesirable to owners have a demonstrable genetic component. Some behaviours are breed-specific, such as the livestock guarding by maremmas and flank sucking seen in Dobermanns. While the identification of genes responsible for common canine diseases is rapidly advancing, those genes underlying behaviours remain elusive. The challenges of accurately defining and measuring behavioural phenotypes remain an obstacle, and the use of variable phenotyping methods has prevented meta-analysis of behavioural studies. International standardised testing protocols and terminology in canine behavioural evaluations should facilitate selection against behavioural disorders in the modern dog and optimise breeding success and performance in working dogs. This review examines the common hurdles faced by researchers of behavioural genetics and the current state of knowledge.

Transmissible [corrected] dog cancer genome reveals the origin and history of an ancient cell lineage

Canine transmissible venereal tumor (CTVT) is the oldest known somatic cell lineage. It is a transmissible cancer that propagates naturally in dogs. We sequenced the genomes of two CTVT tumors and found that CTVT has acquired 1.9 million somatic substitution mutations and bears evidence of exposure to ultraviolet light. CTVT is remarkably stable and lacks subclonal heterogeneity despite thousands of rearrangements, copy-number changes, and retrotransposon insertions. More than 10,000 genes carry nonsynonymous variants, and 646 genes have been lost. CTVT first arose in a dog with low genomic heterozygosity that may have lived about 11,000 years ago. The cancer spawned by this individual dispersed across continents about 500 years ago. Our results provide a genetic identikit of an ancient dog and demonstrate the robustness of mammalian somatic cells to survive for millennia despite a massive mutation burden.

Analysis of associations between behavioral traits and four types of aggression in Shiba Inu

Canine aggression is one of the behavioral problems for which veterinary behaviorists are most frequently consulted. Despite this, the classification of canine aggression is controversial, and there are several classification methodologies. While the etiology of canine aggression differs among the types of aggression, the behavioral background underlying aggression is not well understood. Behavior trait-based evaluation of canine aggression would improve the effectiveness and efficiency of managing canine aggression problems. We developed a questionnaire addressing 14 behavioral items and items related to four types of canine aggression (owner-, child-, stranger- and dog-directed aggression) in order to examine the associations between behavioral traits and aggression in Shiba Inu. A total of 400 Shiba Inu owners recruited through dog events (n=134) and veterinary hospitals (n=266) completed the questionnaire. Factor analysis sorted the behavioral items from both the event and clinic samples into four factors: “sociability with humans,” “reactivity to stimuli,” “chase proneness” and “fear of sounds.” While “reactivity to stimuli” correlated significantly positively with all of the four types of aggression (P=0.007 to <0.001), “sociability with humans” correlated significantly negatively with child- and stranger-directed aggression (P<0.001). These results suggest that the behavioral traits involved in canine aggression differ among the types of aggression and that specific behavioral traits are frequently simultaneously involved in several types of aggression.

Origins of the domestic dog and the rich potential for gene mapping

The unique breeding structure of the domestic dog makes canine genetics a useful tool to further the understanding of inherited diseases and gene function. Answers to the questions of when and where the dog was domesticated from the wolf are uncertain, but how the modern diversity of dog breeds was developed is documented. Breed development has resulted in many genetically isolated populations which are segregating for different alleles for disease and morphological and behavioral traits. Many genetic tools are available for dog research allowing investigation into the genetic basis of these phenotypes. Research into causes of diseases in dogs is relevant to humans and other species; comparative genomics is being used to transfer genetic information to them, including some studies on morphological and behavioral phenotypes. Because of the unique breed structure and well-maintained pedigrees, dogs represent a model organism containing a wealth of genetic information.

Man's best friend becomes biology's best in show: genome analyses in the domestic dog

In the last five years, canine genetics has gone from map construction to complex disease deconstruction. The availability of a draft canine genome sequence, dense marker chips, and an understanding of the genome architecture has changed the types of studies canine geneticists can undertake. There is now a clear recognition that the dog system offers the opportunity to understand the genetics of both simple and complex traits, including those associated with morphology, disease susceptibility, and behavior. In this review, we summarize recent findings regarding canine domestication and review new information on the organization of the canine genome. We discuss studies aimed at finding genes controlling morphological phenotypes and provide examples of the way such paradigms may be applied to studies of behavior. We also discuss the many ways in which the dog has illuminated our understanding of human disease and conclude with a discussion on where the field is likely headed in the next five years.

Behavioral profiles of feline breeds in Japan

To clarify the behavioral profiles of 9 feline purebreds, 2 Persian subbreeds and the Japanese domestic cat, a questionnaire survey was distributed to 67 small-animal veterinarians. We found significant differences among breeds in all behavioral traits examined except for "inappropriate elimination". In addition, sexual differences were observed in certain behaviors, including "aggression toward cats", "general activity", "novelty-seeking", and "excitability". These behaviors were more common in males than females, whereas "nervousness" and "inappropriate elimination" were rated higher in females. When all breeds were categorized into four groups on the basis of a cluster analysis using the scores of two behavioral trait factors called "aggressiveness/sensitivity" and "vivaciousness", the group including Abyssinian, Russian Blue, Somali, Siamese, and Chinchilla breeds showed high aggressiveness/sensitivity and low vivaciousness. In contrast, the group including the American Shorthair and Japanese domestic cat displayed low aggressiveness/sensitivity and high vivaciousness, and the Himalayan and Persian group showed mild aggressiveness/sensitivity and very low vivaciousness. Finally, the group containing Maine Coon, Ragdoll, and Scottish Fold breeds displayed very low aggressiveness/sensitivity and low vivaciousness. The present results demonstrate that some feline behavioral traits vary by breed and/or sex.

Important behavioral traits for predicting guide dog qualification

Guide dogs for the blind help blind people physically and mentally in their daily lives. Their qualifications are based on health, working performance and temperament; approximately 70% of dogs that fail to qualify are disqualified for behavioral reasons. In order to achieve early prediction of qualification, it would be essential as the first step to identify important temperament traits for guide dogs. Therefore, we administered a questionnaire consisting of 22 temperament items to experienced trainers to assess candidate dogs at the Japan Guide Dog Association after three months of training, which was at least three months prior to the final success (qualified as a guide dog) or failure (disqualified for behavioral reasons) judgment. Factor analyses of question items stably extracted three factors with high internal consistency, Distraction, Sensitivity and Docility. When we compared factor points between successful dogs and failed dogs, the successful dogs showed significantly and consistently lower Distraction points and higher Docility points. Additionally, Distraction points could predict qualification with 80.6% accuracy and detect 28.2% of the failed dogs that had higher Distraction points than any of the successful dogs. Of the nine question items not included in the three factors, two items (;Aggression' and ;Animal interest') were consistently associated with qualification. These results suggest that Distraction is stably assessable and has the strongest impact on success or failure judgment; therefore, it will be the first target to establish a behavioral test that may lead to early prediction of guide dog qualification.