Comparison of behavioral characteristics of dogs in the United States and Japan

This study examined the difference in dog owning between Japan and the United States, and the effect of these differences on dogs’ behavioral characteristics. Behavioral evaluations of privately-owned dogs were obtained by using online questionnaire. We compared background and demographic information from the two countries and analyzed the effects of these differences on behavioral characteristics in dogs. The results indicated that there was a bias in the dog breeds kept in Japan compared to the United States and that Japanese dogs’ body weight was lower than the US dogs. The main source of dog acquisition was pet stores in Japan and breeders and/or shelters in the United States. Multiple linear regression analysis found that Japanese dogs showed more aggression to household members and higher energy, restlessness and fear of non-social stimuli than US dogs, while US dogs showed more fear of unfamiliar persons, separation-related behavior and excitability. US dogs also showed higher levels of trainability and attachment to owners. The lower dog’s body weight was, the higher the behavioral scores except for trainability were. When dogs that were obtained under 3 months of age were analyzed, the younger the dogs were when their owners obtained them, the higher the scores on some behavioral problem factors were. The higher rates of problem behaviors among Japanese dogs compared with US dogs suggest that the preference for small breed dogs and poor early development environment influenced the behavioral characteristics of dogs.     

A comparison of the behavioral profiles of purebred dogs in Japan to profiles of those in the United States and the United Kingdom

To clarify the behavioral profiles of 56 pure breeds of dogs in Japan, 96 small-animal veterinarians participated in a questionnaire survey using the same criteria as in preceding studies conducted in the United States and the United Kingdom. We found significant differences among breeds in all behavioral traits examined. In addition, gender differences were revealed in terms of aggression to dogs, territorial defense, excitability, general activity, dominance over owner, destructiveness, watchdog barking, and snapping at children, which were all rated higher in males than females, whereas obedience training and housebreaking ease were rated higher in females. No gender differences were evident in playfulness, excessive barking, or affection demand. Using factor analyses, "aggressiveness", "reactivity", and "trainability" were determined to be consistent with results found in the US and UK surveys. On the basis of these factor scores, seven groups of breeds were determined by cluster analysis to compare to the US survey; 22 of the 38 breeds common with the US survey were categorized into the same groups as those in that survey. The results demonstrated differences in canine behavioral predisposition among breeds and between genders. The similarity in the results between our study and previous surveys, which involved distinct geographical locales, suggests that the genetic basis of breed-specific temperamental traits is manifested irrespective of the cultural or regional identities of the owners.     

Behavioral profiles of dog breeds

Breed behavior profiles were obtained by a method that was quantitative and free of personal biases. The profiles concerned 13 traits, eg, excitability, snapping at children, watchdog barking, and affection demand, which are of interest to people wanting dogs as pets. Authorities for the development of the profiles were 48 small animal veterinarians and 48 obedience judges, randomly selected from directories so as to represent equally men and women, and eastern, central, and western geographic regions of the United States. Each authority was asked to rank on each of the behavioral traits a list of 7 breeds chosen randomly from a list of 56 breeds. The data were analyzed in a custom-designed computer program that pooled the data and then ranked all 56 breeds on the basis of the 13 traits. The results indicated that some behavioral traits discriminate between breeds better than others. An examination of sample profiles indicated the feasibility of developing a statistically meaningful behavioral profile that integrates comparative rankings of several authorities balanced as to representation of geographic location, sex, and type of experience with dogs.     

Dangerous dogs in Berlin in comparison to the dog population--ways to reduce the dangerousness of dogs

The law for handling and control of dogs in Berlin of September 29, 2004 was enacted to prevent the risks for humans and animals when ever they have contact with dogs. "Dangerous dogs" are defined by this law. There are 10 breeds of dogs supposed to be dangerous due to specific characteristics of their breed ("listed breeds"). The dangerousness of a dog's breed is not identical with the dangerousness of an individual dog. The subject of this study is to examine the potential dangerousness of dog breeds and not the individual dangerousness of a dog. This study refers to statistics of incidents between dogs and humans in Berlin for the years 1998 to 2004. The population density of a breed is based on the dogs assessed for tax purposes in Berlin of January 1, 2005 and on the dog registrations maintained at veterinary hospitals. The fourfold-table-test was used to compare the quantity of the recorded incidents of two statistically independent dog breeds. Of the total population of 107,804 tax assessed dogs in Berlin in 2004, 0.9% was documented as dogs involved in incidents with humans. The incidents per year decreased in the "listed breeds"about 68% and in the "unlisted breeds" about 41% during the last 7 years in Berlin. Therefore, the probability (the odds ratio) of a breed to be conspicuous was analysed.The values for the calculation of this probability were the number of dogs of a breed having been involved in incidents compared to the population of this breed based on tax records.The comparison of the probability of a breed with another to be conspicuous was used to compile a cluster of breeds which had the same probability to be conspicuous in 2004. A cluster was assessed for dogs of the following breeds: Sheep dogs, Rottweiler, Doberman, Pitbull Terrier and American Staffordshire Terrier. A listing of breeds is not the right way to reduce the potential dangerousness of a dog, especially in the private domain of their owners. Most incidents with dogs occur in the private domain which normally is not recorded in the statistics of incidents. Therefore, it is more effective to support activities which include the training of abilities of the dog owners.Training by experts can enable dog owners to avoid conflict situations with their dog, or in case of conflict, to take appropriate actions.     

Identification of an cysteine-to-arginine substitution caused by a single nucleotide polymorphism in the canine monoamine oxidase B gene

Monoamine oxidase B catalytically oxidizes biogenic amines such as phenylethylamine and dopamine, and its activity is presumed to be related to particular behavioral traits. In this study, we first identified a single nucleotide polymorphism (T199C) located on the putative third exon of the canine monoamine oxidase B gene, which causes an amino acid substitution from cysteine to arginine. We then examined the allelic frequencies in five dog breeds (Golden Retriever, Labrador Retriever, Maltese, Miniature Schnauzer, and Shiba) and found significant variation among them. The present results suggest that analysis of the monoamine oxidase B polymorphism could be a useful means of elucidating the genetic background of breed-specific behavioral characteristics in dogs.     

Distraction index as a risk factor for osteoarthritis associated with hip dysplasia in four large dog breeds*

Objective : To determine if age, breed, gender, weight or distraction index (DI) influenced the risk of radiographic osteoarthritis (OA) of canine hip dysplasia (CHD) in four common dog breeds; the American bulldog, Bernese mountain dog, Newfoundland and standard poodle. Materials and Methods : This was a cross sectional prevalence study with 4349 dogs. Canine hips were evaluated using 3 radiographic projections: the hip-extended view, the compression view and the distraction view. The hip-extended view was examined for the presence of OA. The PennHIP distraction view was utilized to calculate the DI. For all breeds, a multiple logistic regression model incorporating age, weight, gender, and DI was created. For each breed, disease-susceptibility curves grouping dogs on the basis of age were constructed. Receiver-operating characteristic (ROC) curves were developed for each breed regardless of age. Results : For all breeds, DI was the most significant risk factor for the development of OA associated with CHD. Weight and age were also significant risk factors in all four breeds, but gender was not. Clinical Significance : Results from this study support previous findings, that irrespective of breed, the probability of radiographic OA increases with hip joint laxity as measured by the DI. Breed-specific differences in this relationship, however, warrant investigation of all breeds affected by CHD to determine inherent dependency of hip OA on joint laxity. Such findings guide veterinarians in helping dog breeders to make evidence-based breeding decisions and in informing dog owners to implement preventative treatments for CHD for dogs found to be at risk.     

Novel polymorphism of the canine dopamine receptor D4 gene intron II region

Various dog breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of these characteristics are under genetic control. However, little is known about genes related to behavioral traits in canine species. In humans, it has been reported that the dopamine receptor D4 gene (DRD4) includes polymorphism at several regions that relate to personality or psychiatric disorders. In an earlier study by the authors of the present study, the polymorphisms in canine DRD4 exon III and exon I regions were reported. In the present study, a novel polymorphism in canine DRD4 intron II was found based on a 17 base pair insertion/deletion, and the two alleles detected were named P (shorter allele) and Q (longer allele). The allelic distribution in 28 breeds of dog, including a total of 1114 unrelated individuals, were then investigated. Both P and Q alleles were detected in most of the breeds investigated; however, the frequencies of P and Q differed greatly between breeds. With respect to classification based on breed origin, P and Q alleles were frequent in Occidental and Oriental breeds, respectively. Furthermore, two subspecies of wolves, the ancestors of dogs, were analyzed for the comparison of allele frequencies with dogs, and the P allele was predominant in both European and Chinese wolves.     

Dog and owner characteristics affecting the dog–owner relationship

The nature of the relationship between companion dogs and their owners has important impact on the effect of life for both dog and owner. Identifying factors that affect the dog–owner relationship will assist the understanding of how the successful relationship is achieved and how the less successful relationship is mended, with potential benefits for the welfare of both species. In the present study, we investigated the effect of several dog and owner characteristics, including the personality of the dog, on the dog–owner relationship as measured by the Monash Dog Owner Relationship Scale (MDORS). Data were collected by inviting owners of dogs that had been tested on the Danish Dog Mentality Assessment (DMA) to answer an online questionnaire. We were able to match 421 owner answers with their dogs' DMA test results. The questionnaire consisted of the 28 items of the MDORS, as well as questions about the owners and their dogs. Using factor analysis, 5 dog personality traits could be derived from the dogs' test results on the DMA. The predictive value of questionnaire-based owner and dog variables and the 5 dog personality traits on the dog–owner relationship was tested using multiple linear regressions: 1 for each of the 3 subscales of the MDORS. Overall, the variables investigated only predicted a small proportion of the variance in MDORS scores, and owner characteristics appeared to influence the dog–owner relationship more than dog personality traits did. We found that children in the family and using the dog only for company were negatively associated with the owners' perception of the relationship with their dogs. The only dog characteristics to predict the dog–owner relationship were fearfulness and fear-related behavior problems.     

Dog sperm swimming parameters analysed by computer‐assisted semen analysis of motility reveal major breed differences

Dogs have undergone an intensive artificial selection process ever since the beginning of their relationship with humans. As a consequence, a wide variety of well‐defined breeds exist today. Due to the enormous variation in dog phenotypes and the unlikely chance of gene exchange between them, the question arises as to whether they should still be regarded as a single species or, perhaps, they be considered as different taxa that possess different reproductive traits. The aim of this study was therefore to characterize some male reproductive traits, focusing on kinematic characteristics of dog spermatozoa from several breeds. Thirty‐seven dogs from the following breeds were used: Staffordshire Bull Terrier, Labrador Retriever, Spanish Mastiff, Valencian Rat Hunting Dog, British Bulldog and Chihuahua. Semen samples were obtained via manual stimulation and diluted to a final sperm concentration of 50 million/ml, and they were subsequently analysed by the computer assisted semen analysis (CASA‐Mot) ISAS^®v1 system. Eight kinematic parameters were evaluated automatically. All parameters showed significant different values among breeds and among individuals within each breed. The fastest sperm cells were those of Staffordshire Bull Terriers and the slowest were recorded in Chihuahuas. The intra‐male coefficient of variation (CV) was higher than the inter‐male CV for all breeds with the Staffordshire Bull Terrier showing the lowest values. When taking into consideration the cells by animal and breed, discriminant analyses showed a high capability to predict the breed. Cluster analyses showed a hierarchical classification very close to that obtained after phylogenetic studies with genome markers. In conclusion, future workers on dog spermatozoa should bear in mind major differences between breeds and realize that results cannot be extrapolated from one to another. Because sperm characteristics are associated with breed diversity, dogs may represent a good model to examine changes in reproductive parameters associated with selection processes.     

Canine and human factors related to dog bite injuries

OBJECTIVE: To identify physical traits of biting dogs and characteristics of injured persons and dog owners associated with bite situations for use in public health prevention activities. DESIGN: Retrospective cohort study. STUDY POPULATION: Licensed dog and dog bite report data from June 30, 2002, to July 1, 2003, that were obtained from Animal Control Services of Multnomah County, Oregon. PROCEDURES: To determine the canine and human factors associated with dog bite injuries, the number of bites, dog and injured person characteristics, and the overall canine population were evaluated. Dog owner characteristics at the block group level were defined by use of geographic information system software through 2000 census information based on place of residence. RESULTS: During the study period, 636 dog bites were reported to Animal Control Services, and 47,526 dogs were licensed in Multnomah County. Risk factors associated with biting dogs included breed (terrier, working, herding, and nonsporting breeds), being a sexually intact male, and purebred status. Male children aged 5 to 9 years had the highest rate of injury (178 bites/100,000 children). Biting dogs were more likely than nonbiting dogs to live in neighborhoods where the residents' median incomes were less than the county median income value ($41,278). CONCLUSIONS AND CLINICAL RELEVANCE: Dog bites continue to be a source of preventable injury. Prevention programs should target owners of sexually intact male and purebred dogs and owners who live in lower income neighborhoods.     

Hereditary congenital heart defects in dogs

Congenital heart defects is probably the most common class of malformations found in dogs, occurring with a frequency approaching 1 per cent in animals presented to veterinary clinics. The frequency is significantly higher among purebred dogs than in dogs of mixed breeding and specific anatomic malformations occur with highest frequency in certain breeds. Genetic studies of patent ductus arteriosus, pulmonic stenosis, subaortic stenosis, ventricular septal defect, tetralogy of Fallot and persistent aortic arch have confirmed that these are specific heritable defects, the genes for which are concentrated in a number of different breeds. Each of these defects is inherited in a complex manner consistent with a polygenic basis. This paper will describe evidence supporting the view that the common forms of congenital heart disease in the dog are polygenic threshold traits. The general criteria for recognition of polygenic traits and methods for their control will be discussed.     

Allelic variation of the D4 dopamine receptor polymorphic region in two dog breeds, Golden retriever and Shiba

The D4 dopamine receptor (D4DR) polymorphic region, which is possibly related to the personality trait known as novelty seeking in humans, was examined in 34 dogs from two breeds (Golden retriever and the Japanese indigenous breed, Shiba) by the polymerase chain reaction (PCR), and the DNA sequences of each allele were determined. The polymorphic region of the dog D4DR gene was composed of 39- and 12- base pair (bp) units, and four alleles (A-D) were identified based on the number and/or order of these units. Intra- and inter-breed allele variations were observed. The frequency of the short A allele was dominant (78.9%) in the Golden retriever, while the long D allele was most common (46.7%) in the Shiba. These findings suggested that the allele frequency varied significantly between different breeds, and that analysis of the polymorphism in D4DR might be of use for understanding the behavioral traits of dogs.     

Lack of correlation between canine heart rate and body size in veterinary clinical practice

Objectives : An association between heart rate (HR) and bodyweight has been reported in dogs and it is common belief that small breeds of dog exhibit higher HR than large breeds. The first aim of this study was to test the null hypothesis that, in veterinary clinical practice, bodyweight does not affect HR measured in healthy dogs. A second objective of this investigation was to assess whether other variables, such as gender, breed morphology, age and demeanour, may have a significant effect on dog’s HR measured in a clinical setting. Methods : The investigation was performed via two different studies: a retrospective analysis performed on 243 electrocardiogram recordings and a prospective study based on 153 standardised clinical examinations. Results : The two separate studies did not show any significant correlation between HR and bodyweight (P=0·5705 and P=0·4682, respectively). Subject’s breed morphology and gender did not appear to affect HR measured under these circumstances. However, dogs under the age of one year seem to have significantly higher HRs than older dogs (P < 0·05). Finally, subject’s demeanour was also found to have a significant influence on HR; lower values were recorded in relaxed dogs, and higher rates were documented in excited, nervous dogs (P < 0·05). Clinical Significance : Normal HR could be erroneously interpreted as bradycardia or tachycardia if bodyweight was to be considered a determinant factor. Instead, HR in healthy dogs undergoing routine clinical examination is related to their demeanour or age, if younger than 12 months, but does not appear to be related to bodyweight.     

Assessment of the factorial structures of the C-BARQ in Japan

In order to introduce the Canine Behavioral Assessment and Research Questionnaire (C-BARQ), which is a standardized system for evaluating the behavioral traits of dogs, to Japan, where the environment with respect to dog ownership is thought to differ from those of the United States and Europe, we compared demographic information on dogs in the United States and Japan and examined whether similar factors could be extracted from both countries using questionnaire items of the C-BARQ. The C-BARQ was completed by 11,410, and 734 dog owners respectively in the United States and Japan, and some demographic differences were found, such as breed and neuter status. Data from completed questionnaires were subjected to factor analysis, and the resulting factors were tested for reliability. In the United States, factor analysis yielded 11 factors from 63 items that accounted for 52.9% of the common variance. In Japan, 15 factors were extracted, and these accounted for 57.0% of the common variance. The present factors for the United States were almost identical to the factors identified in a previous study, and similar factors were extracted in both countries. Therefore, the C-BARQ can function effectively as a fundamental behavioral evaluation system for dogs in Japan.     

Lineage classification of canine inheritable disorders using mitochondrial DNA haplotypes

To estimate the maternal effects of dog breeds using mitochondrial DNA(mtDNA) haplotypes in the dogs with several clinical disorders, 600 base pairs of mtDNA D-loop region were amplified from 365 dogs and were determined for mtDNA sequences. The diversity of the 600-bp sequences was classified into 64 haplotypes, including 46 newly discovered haplotypes, and the haplotypes were grouped into four clusters I to IV. Lineage analysis using the mtDNA haplotype indicated that each dog breed genetically comprises one or a few mtDNA haplotypes. When the relationship between genetic background and occurrences of clinical diseases was estimated, canine lineage analysis using mtDNA haplotype revealed that the disorders distributed in the dominant mtDNA haplotypes of each dog breed, but no disorder closely associated with mtDNA haplotypes was detected.     

Posterior capsular opacification in diabetic and nondiabetic canine patients following cataract surgery

Posterior capsular opacification (PCO) is the most common postoperative complication of contemporary cataract surgery. Limited information is available regarding PCO formation and factors that influence PCO development in the dog. Two hundred sixty-five eyes (144 from diabetic dogs and 121 from dogs with breed-related cataracts) were prospectively evaluated for PCO formation for up to 12 months postoperatively. The mean age of all dogs in the study was 7.77 years and diabetic dogs were significantly older than dogs with breed-related cataracts. There were 73 males (61 neutered, 12 intact) and 74 females (70 neutered, 4 intact) in the study. Statistical analysis was performed based on age, breed/size, gender, stage of cataract at the time of surgery, PCO score at each time point, breed-related vs. diabetic cataract, right eyes compared to left eyes, and presence/absence of uveitis. Age and gender did not significantly influence PCO formation. Small and medium-sized breeds developed significantly more PCO in comparison to the large/giant breeds at 2 weeks and 2-4 months postoperatively, but the differences were not significant at later time points. There was an overall significant increase in PCO formation in eyes with early immature cataracts when compared to other stages of cataract up to 4 months postoperatively but not at later time points. There were no statistical differences in PCO score at 6 months or at 1 year postoperatively in eyes with breed-related and diabetic cataracts. Right eyes did not differ from left eyes in PCO score. PCO score significantly increased over time in breed-related and diabetic groups and in the overall population. No difference was found in the degree of PCO formation in eyes with inflammation prior to or after surgery compared with those without inflammation. In summary, age, gender, presence of inflammation, and cause of cataract (breed-related vs. diabetes mellitus) do not influence the development of PCO in canine cataract dogs. Small and medium-sized breeds develop significant PCO earlier than larger breeds. It is important to note that all eyes from all dogs in this study developed PCO in a time dependent manner.     

Demographic characteristics of dog population in Switzerland

Dog Registration data from three Cantons, patient data of 13 veterinary practices and registrations in the Swiss Dog Pedigree Book were collected, analysed and compared to results of a commercial household survey, to assess demographic characteristics of dog population in Switzerland. The proportion of "pure-bred" dogs was different depending on how the term was used, varying from 24% regarding registrations in the Swiss Dog Pedigree Book, to 75% regarding dogs with only one breed recorded in Veterinarian's patient-history-management systems. Most popular breeds were dogs called "German Shepherd/Shepherd", followed by the Labrador and Golden Retriever. Comparison of different data sources suggested regional differences in popularity of breeds. The average life expectancy was estimated on 10.5 and 11 years. Sex distribution was equal. One third of all male dogs and half of the female dogs were neutered. Regardless sex, neutering was more common in cross-bred dogs than in "pure-bred" dogs (OR = 1.9). Some bias in all sources had to be considered and there was a major concern regarding definition of breeds. However, the study was able to add different parameters out of different sources to a homogenous picture of demographic data of dog population in Switzerland.     

Gestational diabetes mellitus in 13 dogs

Background: There are few reports on the clinical appearance, prognosis, and risk factors for gestational diabetes mellitus (GDM) in dogs. Objective: To describe the clinical characteristics of GDM in dogs. Animals: Thirteen dogs with GDM. Methods: Retrospective study. Medical records were reviewed and owners and referring veterinarians were contacted for follow‐up information. Results: Nordic Spitz breeds (11/13 dogs) were overrepresented in the case material. Diagnosis was established at a median of 50 days after mating (range, 32–64). Median glucose concentration at diagnosis was 340 mg/dL (18.9 mmol/L) (range, 203–587). One dog was euthanized at diagnosis, 5 bitches were treated with insulin until whelping, and in 7 dogs, pregnancy was terminated within 4 days of diagnosis. One dog died after surgery. Tight glycemic control was not achieved in any of the insulin‐treated dogs during pregnancy. Diabetes mellitus (DM) resolved in 7 dogs at a median of 9 days after the end of their pregnancies and DM was permanent in 4 dogs. Puppy mortality was increased compared with offspring of healthy dams. Conclusion: This report suggests that GDM affects mainly middle‐aged bitches in the 2nd half of pregnancy with a breed predisposition toward Nordic Spitz breeds. GDM may resolve within days to weeks after pregnancy has ended. Further research is needed to investigate optimal treatment regimens for dogs with GDM and risk factors for unsuccessful outcome.     

Segmental inertial properties in dogs determined by magnetic resonance imaging

Data regarding the segmental inertial properties of the dog are currently unavailable, although such parameters are needed for dynamic analyses of canine motion. The purpose of this study was to measure the segmental inertial properties in three medium sized dogs of average build using magnetic resonance imaging. The parameters included the mass, location of centre of mass and moments of inertia for each body segment. The normalised results will serve as a preliminary foundation for various biomechanical studies in dogs, although further study is required to characterise them for specific dog breeds and to determine how they may be affected by age and gender.     

昆明犬群体遗传结构及受选择基因分析

旨在以昆明犬为主要研究对象探究昆明犬-国内唯一培育并广泛使用的工作犬品种的遗传多样性和群体遗传结构。本试验共采集16头昆明犬(3个品系)、4头马里努阿犬、4头德国牧羊犬血样并提取基因组DNA，用Illumina CanineHD Beadchip芯片对24头3个品种犬进行主成分分析(PCA)、STRUCTURE和邻接(NJ)树分析，检测3个品种警犬的遗传群体结构，并分析昆明犬选育中可能受到选择的候选基因。结果显示，芯片数据根据质控标准最终有86 270个SNPs被筛选出来用于分析。STRUCTURE群体结构分析表明，K=2时德国牧羊犬(DM)和其他品种犬完全区分开来，K=3时马里努阿犬(ML)可以和其他两个品种区分出来，昆明犬中存在部分德国牧羊犬的杂合。PCA和NJ树分析均能将3个品种犬清楚地分开。通过在常染色体上设置500 kb的滑动窗口和将这些区域注释后得到22个在昆明犬品种形成过程中可能受到正选择的基因，主要是参与腺苷酸环化酶活化g蛋白偶联受体信号通路的基因及蛋白和在神经元轴突的生长锥中影响轴突和前导突起生长的基因。本研究探讨了中国昆明犬与其他品种犬的遗传关系,为昆明犬受到强烈的人工选择而产生调节学习、记忆、应激刺激等适应的遗传机制提供了重要的参考。