Dog Breeds Research Articles

Modern pedigree dogs in the United Kingdom Kennel Club: a journey through shifting population landscapes and demography

BackgroundThe limited genetic diversity in pedigree dog populations and the associated increased burden of inherited disease have led to calls for the development and implementation of effective population management strategies. Such strategies must be rooted in a thorough understanding of the genetic reserves and demographics of each population to be managed. Although numerous studies have examined the genetic diversity within various dog breeds, information on the structure of breeding populations and the characteristics of the dogs used for breeding is scarce. Furthermore, the few existing estimates typically represent the most common breeds, which may not be directly relevant for many of the numerically smaller breeds. We examined the demographic parameters of all 222 pedigree breeds recognised by The Kennel Club (KC) in the UK between 1990 and 2021. A meta-analysis was used to test whether all breeds can be represented by a single pedigree dog population, establish reference values for that population and determine the presence of significant variability between breeds.ResultsOverall, the KC-registered pedigree dog population is declining in size, and the percentage of dogs used in breeding is low. Dogs which have been successful in activities such as conformation shows and field trials have been popular in breeding. However, their use in breeding is in decline, partly in favour of imported dogs. The number of imported dogs, and their use in breeding have increased over time, particularly following amendments to the Pet Travel Scheme (PETS) in 2012. Across analyses, the within-breed estimates varied significantly, with the proportion of variation attributed to true variability between breeds exceeding 90% for the majority of estimates.ConclusionThe results of this study provide reference values which can be used to describe the demographics of the KC-registered pedigree dog population and its changes over the last three decades. However, the significantly high variability observed between breeds does not support the hypothesis of a single pedigree dog population and underlines that population management strategies must be tailored to the unique circumstances of each breed.

Incidence of Medial Meniscus Injury Detected by Arthroscopy in Toy Breed Dogs (≤5 kg) with Cranial Cruciate Ligament Rupture.

To investigate the frequency and factors of medial meniscal injury (MMI) associated with cranial cruciate ligament rupture (CrCLR) in toy breed dogs by arthroscopic evaluation.Toy breed dogs (≤5 kg) diagnosed with CrCLR using stifle arthroscopy were included. Age, sex, body weight, breed, medial patellar luxation grade, degree of lameness at diagnosis, and duration of lameness until diagnosis were obtained from medical records. The tibial plateau angle was evaluated using preoperative radiography. On arthroscopic evaluation, degree of CrCLR was classified as partial or complete; MMI was classified as no, mild, or severe injury. MMI grade was used as objective variable; ordered logistic regression was used, and the final model was created using forward-backward stepwise selection.Overall, 202 stifles of 178 dogs were evaluated. Arthroscopic evaluation revealed partial and complete CrCLR, and MMI in 58, 144, and 74 stifles, respectively. MMI with mild and severe damage was noted in 50 and 24 stifles, respectively. Final model included body weight, lameness score, and degree of cranial cruciate ligament damage. A grade 3 lameness score had a higher MMI factor than grade 1. Higher body weight was associated with MMI, and complete rupture had a higher MMI factor than partial tears.Arthroscopic evaluation of CrCLR cases showed MMI in toy breed dogs. Cases with complete CrCLR or severe lameness are at high risk of MMI and should be evaluated cautiously.

Skull Morphology of Shepherd Dogs in Poland

This study aims to assess the skull morphological features of shepherd dog breeds raised in Poland, with an emphasis on native breeds such as the Tatra Sheepdog and Polish Lowland Sheepdog, by utilizing a detailed dataset to analyze and compare the structural traits of their skulls. To achieve this, a total of 32 dog skulls were modeled in 3D, and geometric morphometric analysis was performed to reveal skull shape variations. Among the shepherd samples used, the Polish Lowland Sheepdog exhibited the smallest average skull size. The Tatra Shepherd Dog displayed a skull size similar to that of other sheepdog breeds, although it was larger than that of the Polish Lowland Sheepdog. The results indicate that the Tatra Shepherd Dog possesses a more robust and elongated skull structure compared to the Polish Lowland Sheepdog. Both of these Polish shepherd breeds share similar skull morphology with other shepherd breeds, with the notable exception of collies. Collie breeds exhibit a markedly dolichocephalic skull morphology that sets them apart from the other samples in this study. The analysis revealed that neither Procrustes distance nor shape variation from PC1 had a statistically significant effect on skull size. To enhance our understanding of Poland's shepherd dog diversity, future studies should focus on expanding the dataset to include additional native Polish breeds and exploring a broader range of morphological features beyond the skull.

Vector-borne pathogens in dogs from the Republic of Kosovo

BackgroundCanine vector-borne pathogens (CVBP) are transmitted by arthropod vectors such as ticks, fleas, mosquitoes, and phlebotomine sand flies and are of global veterinary and medical importance. Dogs are important reservoir hosts, which may develop potentially life-threatening clinical signs. The Balkan area harbors diverse vector fauna and associated CVBPs, and data, particularly from the Republic of Kosovo, are scarce. Considering the high number of stray and privately owned dogs primarily kept outside, living in close contact with dogs might promote spillover of zoonotic pathogens to human populations. To combat these diseases, a One Health approach is required. Therefore, our study molecularly analyzed samples of dogs for CVBP.MethodsBlood samples of 276 dogs originating from all seven districts of Kosovo collected from 2021 to 2022 were screened using polymerase chain reaction (PCR) and sequencing for a substantial set of pathogens, including Anaplasma spp., Babesia spp., Bartonella spp., Ehrlichia spp., Filarioidea, Hepatozoon spp., Mycoplasma spp., Rickettsia spp., and Trypanosoma spp. Prevalence rates were statistically assessed on the basis of various factors such as sex, breed, age, and district.ResultsIn total, 150 (54.3%) dogs tested positive for at least one pathogen, comprising eight species of five genera. The most prevalent pathogens detected were Candidatus Mycoplasma haematoparvum (55; 19.9%), Hepatozoon canis (52; 18.8%), and Mycoplasma haemocanis (49; 17.8%). We also detected double (32; 11.6%) and triple (5; 1.8%) infections, with the latter involving combinations of Mycoplasma spp., Dirofilaria repens, Dirofilaria immitis, H. canis, or Babesia vulpes. In addition, prevalence rates were calculated and mapped by district. Of all included factors, significant prevalence differences were found for purebred/mixed breed dogs as well as between age groups.ConclusionsThis study provides the first comprehensive polymerase chain reaction (PCR)-based screening and detection of vector-borne pathogens in dogs from Kosovo and highlights the circulation of pathogens with high veterinary importance and zoonotic potential.Graphical

Subchondral bone density changes of the talus in dogs with tarsocrural osteochondrosis

BackgroundOsteochondritis dissecans (OCD) and osteochondrosis (OC) are multifactorial developmental joint diseases that can occur in various anatomical locations, including the tarsus of immature, rapidly growing large breed dogs. The pathogenesis of canine OCD and OC involves a disruption in endochondral ossification, resulting in a failure of matrix calcification and vascular invasion. This study aimed to investigate the subchondral bone density changes in Labrador Retrievers with tarsocrural OCD/ OC.ResultsA total of 8 dogs with unilateral tarsocrural OCD/ OC were included in the study and density was evaluated with Computed Tomography osteoabsorptiometry (CTOAM ). The findings revealed a significant decrease in subchondral bone density at the location of the OCD/ OC lesion, particularly at the medial trochlear ridge. This area of low density was surrounded by a higher density rim. Furthermore, the contralateral joint showed a significantly higher overall mineral density.ConclusionThese results highlight the significant changes in bone mineral density associated with tarsocrural OCD/ OC. The lower density in the affected joint suggests pathological alterations in the subchondral bone, which may impact the bone turnover and contribute to the development of secondary osteoarthrosis, subsequently. The higher density observed in the contralateral joint emphasizes the role of altered joint loading and adaptation in the subchondral bone.

Common variants in the CPT1A gene are associated with cataracts in Northern breeds of domestic dog.

Primary hereditary cataract affects many purebred domestic dog breeds and is a major cause of visual impairment in dogs. Cataracts are common in Northern breeds such as the Siberian Husky, Alaskan Malamute and Samoyed, but their aetiology is currently unknown. Only two genetic loci are known to be causally related to primary hereditary cataracts in the dog. To search for genetic loci associated with cataracts in Northern breeds, we used a genome-wide association study approach in three breeds-Siberian Husky, Alaskan Malamute and Samoyed. Cases were defined as dogs with bilateral posterior polar subcapsular cataracts and controls were at least four years of age with no evidence of cataracts or other ocular abnormality. We found a genome-wide statistical association for cataracts in the Siberian Husky on canine chromosome 18 (P-value: 1.1 x 10 - 7), which was independently replicated in a second larger case-control set (P-value 9.8 x 10 - 29). The Samoyed breed also showed evidence for association in the same genomic region (P-value: 2.4 x 10 - 5). We subsequently used targeted resequencing of the associated region (6.5 Mb) in ten Siberian Huskies and whole genome sequencing of a Husky, Malamute, Samoyed and Norwegian Buhund case to conduct fine-mapping and screen for candidate causal variants. These analyses identified a region of linkage disequilibrium in the four breeds containing common variants in the carnitine palmitoyltransferase 1A (CPT1A) gene that are strongly associated with bilateral posterior polar subcapsular cataracts in the Siberian Husky, Samoyed, Icelandic Sheepdog and Norwegian Buhund and we demonstrate that CPT1A is expressed in the dog lens and retina through RNAseq. Our findings represent a novel locus for cataracts in dogs. However, further work is needed to elucidate the pathophysiology underlying the association between CPT1A and cataracts in Northern breeds.

A pilot study of mercury in Greenland sled dogs in Greenland: civilian versus military owned dogs. Greenlandic: Mississueqqaarneq Qimmit Qimuttut Aavani Meqquinilu Kviksiilveqarnersut.

A pilot study of mercury in Greenland sled dogs in Greenland: civilian versus military owned dogs. Greenlandic: Mississueqqaarneq Qimmit Qimuttut Aavani Meqquinilu Kviksiilveqarnersut.

Reduction of repetitive tail chasing in a mixed breed dog using multimodal therapy

Reduction of repetitive tail chasing in a mixed breed dog using multimodal therapy

Environmental interference and declining male fertility.

Declining human male 'fertility' has been equated with a temporal decline in sperm counts, with reports collectively spanning the period between 1934 and 2018. Although sperm quality is impacted by adult male lifestyle choices, e.g. diet, stress and exposure to heat, environmental factors are thought to be central to this alarming observation. Since the decline in sperm counts reflects the outputs of meta-analytical studies, and thus the combination of data from different laboratories, statistical models have had to control for potential confounders, including differences in laboratory methodologies, changes in quality assurance standards, age, fertility group and exclusion criteria indicators. Sperm analyses arising from a population of stud dogs, where all analyses were carried out in a single laboratory, demonstrated a 30% decline in sperm motility over 26years. Since these dogs resided in normal homes and were therefore exposed to the same household environment as human cohabitees, it has been postulated that the temporal decline in both dog and human sperm quality reflects environmental interference. This viewpoint article explores this contention and its implications for male 'fertility'.

Analysis of canine gene constraint identifies new variants for orofacial clefts and stature.

Dog breeding promotes within-group homogeneity through conformation to strict breed standards, while simultaneously driving between-group heterogeneity. There are over 350 recognized dog breeds that provide the foundation for investigating the genetic basis of phenotypic diversity. Typically, breed standard phenotypes such as stature, pelage, and craniofacial structure are analyzed through genetic association studies. However, such analyses are limited to assayed phenotypes only, leaving difficult to measure phenotypic subtleties easily overlooked. We investigated coding variation from over 2,000 dogs, leading to discoveries of variants related to craniofacial morphology and stature. Breed-enriched variants were prioritized according to gene constraint, which was calculated using a mutation model derived from trinucleotide substitution probabilities. Among the newly found variants was a splice-acceptor variant in PDGFRA associated with bifid nose, a characteristic trait of Çatalburun dogs, implicating the gene's role in midline closure. Two additional LCORL variants, both associated with canine body size were also discovered: a frameshift that causes a premature stop in large breeds (>25 kg) and an intronic substitution found in small breeds (<10 kg), thus highlighting the importance of allelic heterogeneity in selection for breed traits. Most variants prioritized in this analysis were not associated with genomic signatures for breed differentiation, as these regions were enriched for constrained genes intolerant to nonsynonymous variation. This indicates trait selection in dogs is likely a balancing act between preserving essential gene functions and maximizing regulatory variation to drive phenotypic extremes.

Brachycephaly, Ear Anatomy, and Co-Does Size Matter? A Retrospective Study on the Influence of Size-Dependent Features Regarding Canine Otitis Externa.

This study, which involved 868 patients, focused on size-dependent features (body size, pinna formation, brachycephaly, overweight) and their associations with the occurrence of canine Otitis externa. Breed, sex, and neuter status were also included. Canine patients diagnosed with Otitis externa presented between 1 January 2019 and 31 July 2022 in a referral small animal hospital were included, while dogs with matching categories presented at the Unit for Reproductive Medicine in the same time period functioned as a randomized control group. Statistical analyses included Pearson-Chi2 test, Fisher's exact test, and Bonferroni correction. p-values of <0.05 were considered statistically significant. Rhodesian Ridgebacks, non-brachycephalic breeds, intact female dogs, dogs with semi-erect ears, and large-sized breeds had a significantly reduced risk of developing Otitis externa. Conversely, Pugs, French Bulldogs, Cocker Spaniels, medium-sized breeds, dogs with erect ears, brachycephalic breeds, neutered female, and neutered male patients were more frequently diagnosed with Otitis externa. The study concluded that large breed dogs showed a reduced risk of developing Otitis externa in our data set as well as meso- and doliocephalic breeds and dogs with semi-erect pinna formation. Particularly, the Rhodesian Ridgeback and intact female dogs showed a significantly low risk of suffering from Otitis in the current study.

Dextromethorphan phenotyping of healthy pet dogs reveals breed-associated differences in cytochrome P450 2D15-mediated drug metabolism.

To determine the population variability in dextromethorphan metabolism by cytochrome (CY) P450 2D15 (CYP2D15) in dogs. Healthy pet dogs were recruited from 2018 through 2024 from the Inland Pacific Northwest and phenotyped by orally administering the Program in Individualized Medicine cocktail, which contains dextromethorphan, a CYP2D15-specific probe drug. Glucuronidase-treated urine samples collected 6 hours after dosing were assayed for dextromethorphan and dextrorphan concentrations. Log-transformed metabolic ratios of dextrorphan divided by dextromethorphan (DOR/DXM Log MRs) were calculated. Dogs were genotyped for 5 missense CYP2D15 variants. Univariate and multivariate statistical approaches were used to evaluate associations between DOR/DXM Log MRs and demographic variables. 105 dogs, including 34 mixed breeds and 71 dogs from 20 different owner-designated breeds, were enrolled and completed the study. There was a wide distribution of DOR/DXM Log MRs, from 0.97 to 2.76, representing a log unit range of 1.8 (63-fold variation DOR/DXM Log MRs). Log-transformed metabolic ratios of dextrorphan divided by dextromethorphan were normally distributed and unimodal. The mean (± SD) DOR/DXM Log MR was 2.04 ± 0.37. Multiple linear regression analysis showed significant association (R2 = 0.16) between DOR/DXM Log MRs and dog breed for Golden Retrievers (2.26 ± 0.29; N = 23) and Pugs (1.47 ± 0.29; N = 3). Log-transformed metabolic ratios of dextrorphan divided by dextromethorphan were not associated with dog sex, age, weight, or genotype. There is substantial variability in DOR/DXM Log MR values among individuals, which can be partially attributed to differences between breeds. These findings predict high variability in the metabolism of drugs by CYP2D15 associated with differences between dog breeds.

Antimicrobial pressure in healthy breeding dogs vs household animals assessed through the resistance profile of Escherichia coli and coagulase positive Staphylococci.

Antimicrobial pressure in healthy breeding dogs vs household animals assessed through the resistance profile of Escherichia coli and coagulase positive Staphylococci.

LCORL and STC2 Variants Increase Body Size and Growth Rate in Cattle and Other Animals.

Natural variants can significantly improve growth traits in livestock and serve as safe targets for gene editing, thus being applied in animal molecular designed breeding. However, such safe and large-effect mutations are severely lacking. Using ancestral recombination graphs, we investigated recent selection signatures in beef cattle breeds, pinpointing sweep-driving variants in the LCORL and STC2 loci with notable effects on body size and growth rate. The ACT-to-A frameshift mutation in LCORL occurs mainly in central-European cattle, and stimulates growth. Remarkably, convergent truncating mutations were also found in commercial breeds of sheep, goats, pigs, horses, dogs, rabbits, and chickens. In STC2 gene, we identified a missense mutation (A60P) located within the conserved region across vertebrates. We validated the two natural mutations in gene-edited mouse models, where both variants in homozygous carriers significantly increase the average weight by 11%. Our findings provide insights into a seemingly recurring gene target of body size enhancing truncating mutations across domesticated species, and offer valuable targets for gene editing-based breeding in animals.

Utilization of Cone Beam Computed Tomography in Analyzing the Relationship Between the Mandibular Fourth Premolar Tooth Roots, the Mandibular Canal, and Ventral Mandibular Cortex in 81 Small Breed Dogs.

The mandibular fourth premolar teeth (308, 408) and surrounding mandibular bone are subject to pathologies such as periodontal disease, periapical pathology, and mandibular fracture. As such, the locations of these teeth roots in relation to the mandibular canal and the ventral mandibular cortex are important considerations when developing a surgical treatment plan. This study analyzed the 308 and 408 teeth with cone beam computed tomography scans in 81 small breed dogs. There was no statistically significant variance found in distance to the mandibular canal or the mandibular ventral cortex between the individual mesial and distal roots of 308 and 408. The mesial roots of 308 and 408 tended to be lingual and within the mandibular canal, while the distal roots tended to be dorsal and buccal to the mandibular canal. There was a statistically significant variance regarding the mesial roots and distal roots in relation to the mandibular canal.

Eyes or nose: Domestic dogs (Canis familiaris) prefer vision over olfaction when searching for food.

In recent decades, there has been a growing interest in exploring the cognition of domestic dogs. However, the role of olfaction and vision in dogs' perception of everyday situations has been underexplored. To investigate this topic, we used a simple food-searching paradigm. A treat was hidden in one of three locations, either (a) visible from the starting point (vision condition), (b) invisible from the starting point (smell condition), or (c) invisible with an additional decoy treat presented as a distraction (fake condition). About 87 dogs of various breeds were categorized into either the olfactory-focused or the vision-focused group based on their sniffing behavior in a pretest. It was hypothesized that olfactory-focused dogs would preferentially use their sense of smell for task solving, whereas vision-focused dogs would rely more on visual information. Thus, it was expected that dogs of each group would have an advantage in the corresponding condition. However, there was no difference between groups in the duration to find the food in the three conditions. In general, food was approached faster in the vision condition, and dogs in all groups were distracted by the presence of the fake food. Thus, for all dogs, the visual sense was more dominant than the olfactory sense, and they could easily switch between using the two senses. The results are discussed in light of breed differences and general perception skills of domestic dogs. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Transcriptome Analysis of Canine Histiocytic Sarcoma Tumors and Cell Lines Reveals Multiple Targets for Therapy.

Background: Histiocytic sarcoma (HS) is a highly aggressive malignancy characterized by the excessive proliferation of histiocytes in dogs and humans. A subset of dog breeds, including the Bernese Mountain Dog (BMD), show a remarkably high prevalence of HS. Previous work by us and others has identified somatic driver mutations of HS in the PTPN11 and KRAS genes that activate the MAPK pathway in about 60% of canine HS. However, no somatic driver mutations have been identified in the remaining 40%. Objectives: Our goals are to study HS in BMDs to gain insight into the molecular pathogenesis of the disease, and identify rational approaches to therapy. Methods: Here, we report our whole transcriptome analysis of 18 well-characterized BMD HS tumor tissues, as well as three HS cell lines. Results: Our analysis reveals the significant upregulation of molecular pathways involving the FOXM1, AURKB, PLK1, and E2F genes, in HS as well as hemophagocytic HS, providing new information regarding pathways that may be targeted with inhibitors. In addition, we document the expression of multiple checkpoint genes, suggesting the option of treatment with small-molecule inhibitors together with checkpoint inhibitors. Further, we show that the transcriptomes of three canine HS cell lines mirror those of canine patient tumors, further highlighting their potential use in drug discovery and efficacy studies. Finally, we demonstrate, for the first time, that aurora kinase inhibitors are effective in curtailing the growth of HS cells in vitro and show synergism with MAPK inhibition. Conclusions: This study provides the most detailed analysis of the canine HS transcriptome to date, highlighting key pathways in its pathogenesis and suggesting new avenues for both single and combination treatment strategies, which may be pertinent to the treatment of human HS.

Sensing Dog Brain Reactions to Smell by AI Speckle Pattern Analysis

ABSTRACTInvestigation of a dog's brain activity related to their outstanding olfactory capabilities has been a topic of interest among researchers. For this specific study, we identified three areas of the brain that have been shown in previous studies to be relevant during the process of smell discrimination in dogs: the olfactory bulb, hippocampus, and amygdala. We set up a detection structure system based on laser and a camera to capture speckle patterns on the three regions in four dog breeds for smell stimuli: garlic, menthol, alcohol, and marijuana. The results were analyzed using an XGBoost model. Our analysis revealed that the amygdala plays a crucial role in scent differentiation. Our work offers insight into leveraging the features that characterize distinct scents in the canine brain, paving the way for developing a compact device that can interpret and translate a dog's olfactory perceptions for human understanding.

Genetic and Anatomical Determinants of Olfaction in Dogs and Wild Canids.

Understanding the anatomical and genetic basis of complex phenotypic traits has long been a challenge for biological research. Domestic dogs offer a compelling model as they demonstrate more phenotypic variation than any other vertebrate species. Dogs have been intensely selected for specific traits and abilities, directly or indirectly, over the past 15,000 years since their initial domestication from the gray wolf. Because olfaction plays a central role in critical tasks, such as the detection of drugs, diseases, and explosives, as well as human rescue, we compared relative olfactory capacity across dog breeds and assessed changes to the canine olfactory system to their direct ancestors, wolves, and coyotes. We conducted a cross-disciplinary survey of olfactory anatomy, olfactory receptor (OR) gene variation, and OR gene expression in domestic dogs. Through comparisons to their closest wild canid relatives, the gray wolf and coyote, we show that domestic dogs might have lost functional OR genes commensurate with a documented reduction in nasal morphology as an outcome of the domestication process prior to breed formation. Critically, within domestic dogs alone, we found no genetic or morphological profile shared among functional or genealogical breed groupings, such as scent hounds, that might indicate evidence of any human-directed selection for enhanced olfaction. Instead, our results suggest that superior scent detection dogs likely owe their success to advantageous behavioral traits and training rather than an "olfactory edge" provided by morphology or genes.

Genome-wide association study of idiopathic epilepsy in the Italian Spinone dog breed.

Idiopathic epilepsy (IE) has a high prevalence and a severe clinical course in the Italian Spinone breed of dog. A genome-wide association study meta-analysis of 52 cases and 51 controls was conducted to identify genomic regions that may be involved with the development of IE. Subsequent to the meta-analysis, a set of 175 controls and an independent validation set of 23 cases and 23 controls were genotyped for SNPs showing suggestive association with IE to find variants exhibiting evidence of replicable association and to test the predictiveness of SNPs for IE status when combined in a weighted risk score. Although two regions showed statistically significant association with IE in the GWAS meta-analysis, and additional regions with suggestive association were identified, the findings were not emulated in the validation set. This is the first GWAS of IE in the Italian Spinone, and the findings suggest that IE in the breed is not monogenic and demonstrates the challenges when investigating a multigenic or complex inherited disease in a numerically small domesticated animal population.