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Topic:DNA
DNA in horses refers to the genetic material that carries the hereditary information necessary for the growth, development, functioning, and reproduction of equine species. It consists of sequences of nucleotides that encode the genetic instructions used in the development and functioning of horses. DNA analysis in horses can provide insights into genetic diversity, lineage, and breed characteristics. It is also utilized in identifying genetic disorders, understanding hereditary traits, and assisting in selective breeding programs. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and applications of DNA analysis in equine genetics and breeding.
Horse genetics, archaeology, and the beginning of riding. Recent papers argued that the domestication of horses can be equated with the appearance of favorable genetic mutations that are first evident in individuals in the DOM2 clade dated about ∼2200-2100 BCE. We challenge the idea that this genetic shift alone defines domestication. Evidence from archaeology, ancient DNA, osteology, and other disciplines shows that horses from multiple genetic backgrounds (DOM1, DOM2, and, as we suggest here, DOM3) were managed, milked, and ridden long before 2200 BCE. Yamnaya groups (∼3200-2600 BCE) rode DOM2 horses-the direct ancestors of modern domestic stoc...
High frequency and high genetic diversity of Pneumocystis sp. in foals. Twenty-two foals, aged one to seven months, which died from interstitial pneumonia (15 foals) or unrelated illnesses and injuries (7 foals), were enrolled in this study. Sampling of the lungs was performed post-mortem for a total of 52 specimens. Pneumocystis was detected in 21/22 foals (48/52 specimens) using a PCR assay targeting the gene encoding the small subunit of the mitochondrial rRNA (mtSSUrRNA) of the horse-related Pneumocystis (Pneumocystis sp. 'Equus ferus caballus'). The sequencing of the PCR products was successful in 34/48 specimens. The sequences were identical to the horse-rel...
Molecular prevalence of equine parvovirus hepatitis in healthy horses from the Northern region of the state of Rio Grande do Sul, Brazil. The equine parvovirus hepatitis (EqPV-H) was initially linked to fatal cases of equine serum hepatitis but, more recently, it has also been detected in sick or asymptomatic horses around the world, including in a limited number of horses in southeastern Brazil. In this study we aimed to assess the prevalence of EqPV-H DNA in the serum of healthy horses in the northern region of Rio Grande do Sul state, Brazil. For this purpose, we used 1000 serum samples collected from horses from 40 municipalities and organized them into 200 pools of five samples each, based on origin and age. Using a nested ...
Detection of papillomavirus DNA in uterine flushing samples from healthy mares reveals diverse genotypes with differing host ranges. A molecular study to assess the presence of some papillomaviruses was performed on 105 uterine flushing samples of healthy mares using real time quantitative polymerase chain reaction (qPCR) and digital PCR (dPCR). Bovine, equine, and ovine papillomavirus DNA was detected in 27 uterine flushing samples through dPCR (~ 25.71%); qPCR was able to detect 18 positive samples (~ 17.14%). Differences between the two molecular protocols were significant as shown by McNemar's test (p˂ 0.005). EcPV DNA was detected in 10 samples by dPCR (~ 9.52%) of uterine flushing samples. qPCR detected EcPV DN...
Telomere-to-telomere Genome Assembly of Equus kiang (Tibetan wild donkey). The Tibetan wild donkey (Equus kiang) is an endemic equid species inhabiting the Qinghai-Tibet Plateau, exhibiting remarkable chromosomal diversity within the Equus genus. Here we present a chromosome-level, telomere-to-telomere genome assembly for E. kiang generated using Illumina short reads, PacBio HiFi long reads, and Hi-C sequencing data. The final assembly spans 4.02 Gb and comprises 27 pseudochromosomes. Specifically, 8 chromosomes are gapless, 8 chromosomes have one gap, 7 chromosomes have 2-4 gaps, and the remaining 4 chromosomes have five or more gaps. Benchmarking Universal Single...
Machine Learning-Based Genome-Wide Association Study Reveals Genetic Loci Associated with Body Measurement Traits in Yili Horses. Body measurement traits are key indicators for evaluating growth performance, production potential, and breeding value in Yili horses. However, studies investigating the association between body measurement traits and mutation loci in Yili horses remain limited. In this study, 255 adult Yili mares were used as the study population, including 152 speed-type and 103 meat-type individuals. Whole-genome resequencing was performed, and four phenotypic traits and body weight were measured. A mixed linear model (MLM)-based genome-wide association study (GWAS) was conducted using GEMMA (v 0.98.5), inc...
Genomic diversity and structure in arabian horses revealed by whole-genome sequencing: establishment of an allele frequency database of common genetic variation. BACKGROUND: The Arabian horse is a culturally and historically influential breed that has contributed to the development of many modern horse populations. However, genomic resources for this breed remain limited, particularly population-level allele frequency datasets that support studies of genetic diversity, selection, and disease. The aim of this study was to generate a comprehensive allele frequency database for Arabian horses using representative sampling and high-coverage whole-genome sequencing. RESULTS: We generated the first publicly available allele frequency database for the Arabian...
Klossiella equi, an underreported parasite of equids in the Americas. Klossiella equi Baumann, 1946 (Apicomplexa: Coccidia) is a globally distributed adeleorinid parasite that infects the kidneys of equid hosts. Considered an uncommon parasite, when K. equi is detected, it is typically an incidental finding during histologic examination of the kidneys as part of routine necropsy. In the present study, kidney was collected opportunistically from 3 different equine populations: 1) routine necropsies at the Ontario Veterinary College (OVC; n = 48); 2) natural mortalities from the Sable Island wild horse herd (n = 25); and 3) routine necropsies of animals fr...
Genetic diversity in the Criollo Argentino horse from SNP array data. The Criollo Argentino horse is a national symbol and a heritage breed that represents both cultural identity and a key component of traditional production systems in Argentina. This study aimed to assess the genetic differentiation of the Criollo Argentino relative to other horse breeds and to infer potential factors shaping its diversity through the genomic analysis of 24 representative animals. Samples were genotyped using a medium-density SNP array containing 65,157 markers, and genetic diversity analyses were conducted across autosomal SNP sets filtered under different criteria. Contempora...
HERDA-associated variant in bull-catching (vaquejada) Brazilian Northeastern bull-catching Quarter Horses. Bull-catching (vaquejada) accounting for approximately 13% of sport horses in Brazil. Genetic screening has enabled strategies to reduce the spread of inherited disorders, including Hereditary Equine Regional Dermal Asthenia (HERDA), a major skin disease included in the Six Panel required for registration by the Brazilian Quarter Horse Breeders Association. Although the HERDA-associated variant has been extensively studied in other disciplines, it had not been evaluated in Bull-catching Quarter Horses (QH). Objective: The present study aimed to determine the allele frequency of the pathogenic ...
Prevotella mikamonis sp. nov., isolated from equine clinical specimens. In this study, five strains of anaerobic, Gram-negative, rod-shaped bacteria were characterized phenotypically, biochemically and genotypically. These strains were clinically isolated from horse specimens in Japan. Phylogenetic trees constructed based on 16S rRNA gene sequence comparisons showed distinct clustering of the five strains with the type strains of closely related species. The genomic DNA G+C content was 46.7 mol%. The major cellular fatty acids identified were C, 3-OH-C and 3-OH-iso-C. Whole-genome comparisons based on average nucleotide identity using blast (ANIb) and digital DNA...
United States stakeholder insights on genetic testing for equine health and breeding. The S1094 United States Department of Agriculture Multistate Research Project is a collaborative effort utilizing equine genetics and genomics to improve horse health and well-being. It also provides educational resources and genetic testing tools to equine industry stakeholders. Objective: A survey assessed the knowledge, priorities, and information sources of U.S. horse owners and enthusiasts regarding equine genetic testing to inform future outreach and research efforts. Methods: An online survey was distributed from March to October 2024, targeting horse owners and enthusiasts across the U...
DMRT3 Gene Variations in Horse Breeds Selected for Gaited Movement – Established Research and Novel Findings. The DMRT3 gene, often referred to as the "gait keeper," plays a key role in controlling alternative gaits in horses, such as tölt and pace. This study aimed to determine the frequency of known and to screen for potential novel polymorphisms within the second exon of the DMRT3 gene. Methods: A total of 244 blood or hair samples were collected from representative individuals of the six horse breeds: gaited (Icelandic Horse, French Trotter), non-gaited (Arabian Horse, Malopolski Horse), and pony breeds (Welsh Pony, Shetland Pony). Methods: The second exon of the DMRT3 gene analyzed using Sanger ...
Unveiling genetic diversity in Egyptian Arabian horses (Equus caballus) through cytogenetic and ISSR marker analysis. This study combined classical cytogenetics and ISSR molecular markers to characterize genetic diversity in 24 Egyptian Arabian horses. Karyotyping revealed the standard equine chromosome number (2n = 64) with no numerical or structural abnormalities. Chromosome measurements were consistent with ISCN Equine standards: autosomal relative lengths (RL%) followed the expected size hierarchy, biarmed chromosomes displayed metacentric to submetacentric morphology (CI = 37-50%), and recalculated centromeric indices confirmed the presence of measurable p-arms on all acrocentric chromosomes. ISSR an...
An increased number of heterozygous calls in the AxiomTM Equine Genotyping Array. Single nucleotide polymorphism (SNP) arrays are commonly used in livestock genetics to investigate complex traits including genome-wide associations and fine mapping, genomic prediction and genetic diversity analyses. In a European equine diversity study, we analysed the AxiomTM Equine 670K SNP genotype data from 2,768 equids representing 20 horse breeds and one donkey breed. Using a strict detection setting to identify genome-wide runs of homozygosity (ROH), 169 purebred horses displayed fewer ROH segments than F1 crosses. Under medium and relaxed settings, ROH counts increased, while some ho...
Sex determination and genetic screening of equine embryos with whole genome amplification and real-time PCR. Reliable pre-implantation sex determination and genetic screening enables informed embryo transfer decisions in equine breeding while avoiding later interventions. We developed a streamlined workflow that couples rapid whole genome amplification (WGA) with a multiplex real-time PCR targeting ETSTY5 as a Y-specific marker and UBC as an autosomal control. On purified equine DNA, sex was correctly assigned down to 10 pg gDNA and to a single fibroblast cell. Direct testing of embryo biopsies without WGA yielded inconsistent results, whereas introducing a short WGA step produced tight allelic-discr...
Small Genome-wide association study of insect bite hypersensitivity in Hucul horses. Insect bite hypersensitivity (IBH) is a prevalent allergic skin disease in horses that significantly affects animal welfare and shows evidence of genetic predisposition. Objective: Understanding the genetic basis of IBH can improve management and breeding strategies. The Equine80K BeadChip microarray was used to identify genomic regions associated with the occurrence of IBH in Hucul horses. Methods: Hair samples were collected from 127 Hucul horses, including both affected individuals and controls. DNA was extracted and genotyped. A genome-wide association study (GWAS) was performed to identif...
Comparative Evaluation of Sperm Quality Assessment Methods in Purebred Spanish Horses. Evaluating semen quality in Purebred Spanish Horses is essential to determine reproductive potential and optimize assisted reproductive techniques. Objective: This study compared several sperm analysis methods in Purebred Spanish Horses to standardize protocols suitable for both laboratory and field conditions. Methods: Fifteen stallions were evaluated through three ejaculates, analyzing sperm parameters using different techniques. Sperm kinematics was assessed by Sperm Computer Analyzer (SCA-CASA) or iSperm mCASA. Viability was analyzed by eosin-nigrosin-Giemsa (ENG) staining or Hoechst 33258...
Direct single-nucleotide polymorphism genotyping from whole blood without DNA extraction. A subset of single-nucleotide polymorphisms (SNPs) are associated with various phenotypes, including diseases, coat colour, and athletic performance, and are widely used in medical and veterinary fields. In this study, we developed a novel method for direct SNP genotyping from whole blood without DNA extraction. Thoroughbred blood samples were diluted 100-fold with Milli-Q water and analysed using real-time polymerase chain reaction (PCR) with hydrolysis probes. Specificity and sensitivity were improved by increasing the annealing temperature and number of PCR cycles. Genotyping results for SN...
Functional Characterization of Long Non-Coding RNAs Associated with Reproductive Fitness in Pura Raza Española Mares. Long non-coding RNAs (lncRNAs) are transcripts constituted of more than 200 nucleotides that have been associated with the regulation of different biological processes by modulating the expression of key genes. In horses, evidence suggests that lncRNAs play a role in female reproductive fitness, yet their functional implications remain poorly characterized. The objective of this study was to investigate potential DNA:RNA triplex interactions between the promoter regions of fertility-related genes and lncRNAs transcribed from non-coding loci located within ±50 kb of these genes. By doing so, w...
Starch Overload and Cecal Alkalinization: Impacts on the Intestinal Microbiota and Health of Horses. Starch overload induces dysbiosis primarily through a reduction in cecal pH. This study aimed to evaluate the cecal microbiota following excessive starch intake, with or without the administration of an intracecal buffering solution. We hypothesized that the buffering solution would mitigate changes in the intestinal microbiota and associated clinical signs. Ten horses were randomly assigned to two groups, each receiving distinct treatments (Group I: saline solution [WSa] and starch-buffer [SB]; Group II: buffer-water [WB] and starch-saline [SSa]). Following starch overload (17.6 g/kg body wei...
The fertility of a sub-population of stallions is negatively affected by ambient climatic conditions, mediated through DNA damage. Exposure to systemic heat stress in male mammals adversely affects sperm production, fertility, and DNA integrity. To date, few studies have investigated this phenomenon in horses, particularly in industry-relevant environments. Therefore, this study examined the relationship between ambient climatic conditions and fertility within a population of commercially fertile stallions. Post-coital semen samples ( = 804) were collected weekly from 46 Thoroughbred stallions during two successive breeding seasons (NSW, Australia; 22 weeks total). Semen samples were processed via single-layer colloid...
Fully Phased Telomere-to-Telomere Assemblies for Thoroughbred Horse and Donkey Haplotypes derived from a Mule Illuminate the Peculiar Evolution of Equid Centromeres. We present telomere-to-telomere genome assemblies of a Thoroughbred horse and a donkey derived from their mule offspring. Now adopted and annotated by NCBI as reference genomes, these assemblies resolve previously inaccessible regions, including satellite arrays, duplications, and telomeres. Equids are known to exhibit an uncoupling between satellite DNA and centromeric function. The completeness of these assemblies enabled annotation of both satellite-based and satellite-free centromeres, as well as non-centromeric satellite loci, revealing notable centromeric plasticity. They also allowed de...
Association between ultraviolet-related TP53 mutations and immune microenvironment in equine ocular squamous cell carcinoma. This study investigates the molecular and immune characteristics of equine ocular squamous cell carcinoma (eoSCC). Immunohistochemistry (IHC) and next-generation sequencing (NGS) were used to detect protein expression and TP53 mutations, respectively. T lymphocytes (CD3+), regulatory T cells (FoxP3+), B lymphocytes (CD20+), and macrophages (IBA-1+) were quantified. A total of 29 cases of eoSCC were evaluated, consisting of 3/29 carcinomas in situ (CISs) and 26/29 squamous cell carcinomas (SCCs). p53 positivity by IHC was detected in 19/29 cases while by NGS, 21 TP53 mutations were found in 13/...
Beyond the host: Unveiling the independent microbiome of equine gastrointestinal nematodes. Gastrointestinal nematode infections significantly impact equine health and welfare, with rising anthelmintic resistance demanding alternative control strategies. Emerging evidence suggests that parasitic nematodes harbour distinct microbiomes, potentially influencing host-parasite dynamics and parasite survival. This study aimed to characterize and compare the microbiomes of equine gastrointestinal nematodes and their hosts, focusing on differences in composition, diversity, and core microbiota structure across different intestinal sites, nematode subfamilies, and sexes. Faecal and nematode s...
Genome-Wide DNA Methylation Analysis of Performance Variation in the 5000-m Speed Race of Yili Horses. Whole-genome bisulfite sequencing (WGBS) was employed in this article to map blood DNA methylation profiles at single-base resolution in Yili horses before a 5000 m speed race, with comparative analysis of epigenetic differences between the 'elite group' and 'ordinary group' across six four-year-old stallions. The overall methylation level in the elite group was generally higher than that in the ordinary groups, with a minority of regions showing hypomethylation. For instance, the promoter regions of key metabolic and neuro-related genes exhibited significant hypomethylation. The article ident...
Sequencing and Analysis of mtDNA Genomes from the Teeth of Early Medieval Horses in Poland. This study presents the sequencing and analysis of mitochondrial DNA (mtDNA) genomes from nine early medieval horse remains excavated across archaeological sites in Silesia region in present day Poland. Methods: Using aDNA extraction protocols optimized for short fragments, combined with target enrichment and high-throughput sequencing, we reconstructed partial mtDNA sequences for seven of the specimens. Results: The authenticity of the aDNA was confirmed through damage pattern analysis. Phylogenetic reconstruction revealed that the specimens belonged to six distinct mtDNA lineages (B, D, E, G...
Molecular Detection of Theileria equi, Babesia caballi, and Borrelia burgdorferi Sensu Lato in Hippobosca equina from Horses in Spain. The forest fly ) is an obligate haematophagous dipteran insect (order Diptera) that primarily infests horses and may contribute to the circulation of vector-borne pathogens. This study aimed to investigate the presence of , s.l., , and , important vector-borne pathogens of equids, in forest flies collected from horses in endemic areas of Spain. A total of 170 forest flies were collected from 39 equids across four geographical regions in Spain (Segovia, Madrid, Toledo, and Menorca) and blood samples were collected from 27 of these horses. All flies were morphologically and molecularly identifi...
Review: Genomic insights into the adaptive traits and stress resistance in modern horses. The domestication and selective breeding of horses have profoundly influenced the emergence of adaptive traits and stress resistance mechanisms, shaping modern equine populations. This comprehensive review examines the genomic foundations of these traits, emphasizing recent advancements in high-throughput sequencing technologies and bioinformatics. These tools have elucidated the genetic underpinnings of key characteristics such as endurance, speed, metabolic efficiency, and disease resistance. Importantly, the review identifies and connects gene variants associated with thermoregulation, immu...
