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Topic:Phenotype
Phenotype in horses refers to the observable physical and behavioral traits of an individual horse, which result from the interaction of its genetic makeup and environmental influences. These traits include characteristics such as coat color, height, conformation, and temperament. Phenotypic expression is a focal point in equine breeding and management, as it influences performance, health, and suitability for specific disciplines. Research in this area examines the genetic basis of phenotypic traits, the impact of environmental factors, and the interaction between genetics and environment. This page aggregates peer-reviewed research studies and scholarly articles that explore the genetic determinants, environmental effects, and practical implications of phenotypic traits in horses.
Clinical variability of equine asthma phenotypes and analysis of diagnostic steps in phenotype differentiation. Equine asthma is a common, non-infectious, chronic lung disease that affects up to 80% of the horse population. Strict phenotyping and identification of subclinically asthmatic horses can be challenging. The aim of this study was to describe equine asthma phenotypes (mild, moderate, and severe asthma) defined by BALF cytology and occurrence of clinical signs in a population of privately owned horses and to identify the variables and examination steps with best discriminative potential. The standardised examination protocol included clinical examinations, blood work, airway endoscopy with bronc...
The Use of Genomic Screening for the Detection of Chromosomal Abnormalities in the Domestic Horse: Five New Cases of 65,XXY Syndrome in the Pura Raza Español Breed. Sex chromosomal abnormalities are a well-established cause of reproductive failure in domestic horses. Because of its difficult diagnosis, the Pura Raza Español breeding program established a routine screening for chromosomal abnormalities in all the horses prior to enrolling in the studbook. This genomic procedure combines an initial assessment based on the results from Short Tandem Repeat (STR) parentage testing followed by a Single-Nucleotide Polymorphism (SNP) based copy number aberration (CNA) confirmative analysis in positive cases. Using this methodology, we identified five new individ...
An intronic copy number variation in Syntaxin 17 determines speed of greying and melanoma incidence in Grey horses. The Greying with age phenotype in horses involves loss of hair pigmentation whereas skin pigmentation is not reduced, and a predisposition to melanoma. The causal mutation was initially reported as a duplication of a 4.6 kb intronic sequence in Syntaxin 17. The speed of greying varies considerably among Grey horses. Here we demonstrate the presence of two different Grey alleles, G2 carrying two tandem copies of the duplicated sequence and G3 carrying three. The latter is by far the most common allele, probably due to strong selection for the striking white phenotype. Our results reveal a rem...
Prevalence and antimicrobial susceptibility of Streptococcus equi isolated from horses in Santa Catarina state, Southern Brazil. The objective of this study was to determine the prevalence of Streptococcus equi (S. equi subsp equi and S. equi subsp zooepidemicus) in the state of Santa Catarina and evaluate the antimicrobial susceptibility of the isolates. For this, 420 nasal swab samples were collected from randomly selected horses. Isolation and phenotypic characterization of the bacteria were performed by sowing on 5% sheep blood agar, followed by analysis of morphotinctorial characteristics and biochemical analysis. To differentiate the main beta-hemolytic Streptococcus in horses, the fermentation profiles of the sug...
Preliminary investigation of potential links between pigmentation variants and opioid analgesic effectiveness in horses during cerebrospinal fluid centesis. The pleiotropic effects of the melanocortin system show promise in overcoming limitations associated with large variations in opioid analgesic effectiveness observed in equine practice. Of particular interest is variation in the melanocortin-1-receptor (MC1R) gene, which dictates pigment type expression through its epistatic interaction with the agouti signalling protein (ASIP) gene. MC1R has previously been implicated in opioid efficacy in other species; however, this relationship is yet to be explored in horses. In this study, analgesic effectiveness was scored (1-3) based on noted response...
Characterisation of phenotypic patterns in equine exercise-associated myopathies. Equine exercise-associated myopathies are prevalent, clinically heterogeneous, generally idiopathic disorders characterised by episodes of myofibre damage that occur in association with exercise. Episodes are intermittent and vary within and between affected horses and across breeds. The aetiopathogenesis is often unclear; there might be multiple causes. Poor phenotypic characterisation hinders genetic and other disease analyses. Objective: The aim of this study was to characterise phenotypic patterns across exercise-associated myopathies in horses. Methods: Historical cross-sectional study, w...
Coloration in Equine: Overview of Candidate Genes Associated with Coat Color Phenotypes. Variation in coat color among equids has attracted significant interest in genetics and breeding research. The range of colors is primarily determined by the type, concentration, and distribution of melanin pigments, with the balance between eumelanin and pheomelanin influenced by numerous genetic factors. Advances in genomic and sequencing technologies have enabled the identification of several candidate genes that influence coat color, thereby clarifying the genetic basis of these diverse phenotypes. In this review, we concisely categorize coat coloration in horses and donkeys, focusing on t...
Genomic analyses of withers height and linear conformation traits in German Warmblood horses using imputed sequence-level genotypes. Body conformation, including withers height, is a major selection criterion in horse breeding and is associated with other important traits, such as health and performance. However, little is known about the genomic background of equine conformation. Therefore, the aim of this study was to use imputed sequence-level genotypes from up to 4891 German Warmblood horses to identify genomic regions associated with withers height and linear conformation traits. Furthermore, the traits were genetically characterised and putative causal variants for withers height were detected. Results: A genome-wide ...
Monoclonal antibodies for equine CD25 improve detection of regulatory T cells in horses. CD25, the interleukin-2 receptor α-chain, is expressed on cell surfaces of different immune cells and is commonly used for phenotyping of regulatory T cells (Tregs). CD25 has essential roles in the maintenance of hemostasis and immune tolerance and Treg cell involvement has been shown in human diseases and murine models for allergy, autoimmunity, cancer, chronic inflammation, and many others. In horses, a cross-reactive anti-human CD25 antibody has previously been used for characterizing Tregs. Here, we developed monoclonal antibodies (mAbs) to equine CD25 and compared their staining pattern ...
The use of genomic assisted selection could allow early selection among Thoroughbreds and Polo Argentino horses for practicing polo. The Polo Argentino (PA) horse is a recognized breed, developed originally by mixing crossbred and Thoroughbred (TB) horses to play polo. Early PA selection is difficult due to unreliable performance estimations. This study investigated the usefulness of genomic markers previously linked to morphological and functional traits as a tool for the early selection of PA. To this, we genotyped 520 PA and 30 TB horses using the Equine GGPArray (Illumina, n=71,778 SNPs). Analyses included a genetic characterization of six genetic markers associated with behavioral (DRD4), muscular development (MSTN), a...
Towards personalized medicine for the treatment of equine asthma. Although horses with asthma share similar clinical signs, the heterogeneity of the disease in terms of severity, triggering factors, inflammatory profile, and pathological features has hindered our ability to define biologically distinct subgroups. The recognition of phenotypes and endotypes could enable the development of precision medicine, including personalized, targeted therapy, to benefit affected horses. While in its infancy in horses, this review outlines the phenotypes of equine asthma and discusses how knowledge gained from targeted therapy in human medicine can be applied to evaluat...
De novo reconstruction of a functional in vivo-like equine endometrium using collagen-based tissue engineering. To better understand molecular aspects of equine endometrial function, there is a need for advanced in vitro culture systems that more closely imitate the intricate 3-dimensional (3D) in vivo endometrial structure than current techniques. However, development of a 3D in vitro model of this complex tissue is challenging. This study aimed to develop an in vitro 3D endometrial tissue (3D-ET) with an epithelial cell phenotype optimized by treatment with a Rho-associated protein kinase (ROCK) inhibitor. Equine endometrial epithelial (eECs) and mesenchymal stromal (eMSCs) cells were isolated separat...
Whole-Genome Sequencing and Phenotypic Analysis of Streptococcus equi subsp. zooepidemicus Sequence Type 147 Isolated from China. subsp. () is one of the important zoonotic and opportunistic pathogens. In recent years, there has been growing evidence that supports the potential role of in severe diseases in horses and other animals, including humans. Furthermore, the clinical isolation and drug resistance rates of have been increasing yearly, leading to interest in its in-depth genomic analysis. In order to deepen the understanding of the characteristics and genomic features, we investigated the genomic islands, mobile genetic elements, virulence and resistance genes, and phenotype of strain ZHZ 211 (ST147), isolat...
Equine neuroaxonal dystrophy/degenerative myeloencephalopathy in Gypsy Vanner horses. Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disease that primarily affects young, genetically predisposed horses that are deficient in vitamin E. Equine NAD/EDM has not previously been documented in Gypsy Vanner horses (GVs). Objective: To evaluate: (1) the clinical phenotype, blood vitamin E concentrations before and after supplementation and pedigree in a cohort of GV horses with a high prevalence of neurologic disease suspicious for eNAD/EDM and (2) to confirm eNAD/EDM in GVs through postmortem evaluation. Methods: Twenty-six GVs from 1 fa...
Predicted genetic burden and frequency of phenotype-associated variants in the horse. Disease-causing variants have been identified for less than 20% of suspected equine genetic diseases. Whole genome sequencing (WGS) allows rapid identification of rare disease causal variants. However, interpreting the clinical variant consequence is confounded by the number of predicted deleterious variants that healthy individuals carry (predicted genetic burden). Estimation of the predicted genetic burden and baseline frequencies of known deleterious or phenotype associated variants within and across the major horse breeds have not been performed. We used WGS of 605 horses across 48 breeds ...
Effects of tamoxifen on the immune response phenotype in equine peripheral blood mononuclear cells. Tamoxifen (TAM) is widely utilized in the prevention and treatment of human breast cancer and has demonstrated the potential to modulate the immune response. It has been proposed as a therapeutic tool for immune-mediated diseases. TAM has been investigated as a possible treatment for asthma-like conditions in horses, revealing specific impacts on the innate immune system. While the effects of TAM on equine neutrophils are well-documented, its influence on lymphocytes and the modulation of the immune response polarization remains unclear. This study employed peripheral blood mononuclear cells ...
Peptostreptococcus equinus sp. nov., isolated from horse faeces. A Gram-stain-positive, non-spore-forming, and obligate anaerobic bacteria designated strain CBA3647 was isolated from a horse faecal sample in Jeju, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CBA3647 formed a distinct phyletic lineage from closely related species within the genus . Based on comparative analysis of 16S rRNA gene sequences, ATCC 27337 is most closely related to strain CBA3647 with a 16S rRNA gene similarity of 98.31 %, while similarity to other type strains is below 98.0 %. The genomic DNA G+C content of strain CBA3647 was 3...
A case of non-mosaic X trisomy (65,XXX) in a Thoroughbred mare confirmed by cytogenetic and molecular analysis. A 9-year-old Thoroughbred mare with normal external genitalia and regular oestrus symptoms was gynecologically examined prior to insemination. This primary examination revealed the presence of a hypoplastic uterus and the lack of normal ovaries, and the mare was therefore subjected to more detailed diagnostics, including endocrinological, genetic, and clinical tests. Diagnostic imaging with the use of ultrasonography and endoscopy confirmed the underdevelopment of internal genitalia. Analysis of circulating sex hormones revealed very low concentrations of progesterone and oestradiol. Finally, ...
Genome-wide association study suggests genetic candidate loci of insulin dysregulation in Finnhorses. Equine metabolic syndrome (EMS) is a common welfare problem in horses worldwide. It is characterized by insulin dysregulation (ID), predisposition to laminitis and often obesity. EMS is multifactorial by nature, with both the environment and genetics contributing to the phenotype. Environmental factors, such as feeding and exercise, can be controlled, thus forming the basis for treatment and prevention. Genetic factors, by contrast, are less well-known and not easily controllable. The aim of this study was to identify potential genetic loci influencing ID/EMS in Finnhorses. A single-breed (Fin...
Geometric morphometrics of face profile across horse breeds and within Arabian horses: Horse face geometric morphometrics. Horse traits under selection are largely quantitative and affected by multiple genes. Horse face shape is an example of a continuous trait, which due to the reliance on observational assessments, is classified into; "dished", "straight", and "roman-nosed". This categorization is often inadequate to convey the full spectrum of the face shape variation especially for genetic studies. The first objective of the current study was to use geometric morphometric methods to quantitatively phenotype face shapes and examine its variation across horse breeds. The second objective was to analyze the face ...
Digital Phenotyping Reveals Phenotype Diversity and Epistasis among White Spotting Alleles in the American Paint Horse. White spotting is an iconic feature of the American Paint Horse. The American Paint Horse Association (APHA) is dedicated to recording pedigree and performance of this stock-type breed, while preserving its distinctive coat color and conformation. Here, the depigmented proportion of the coat (% white coat) was measured using digital photograph analysis of 1195 registered American Paint Horses. Genotypes for nine white-spotting polymorphisms commonly found in Paint Horses, and two pigment-producing loci and genes, were also provided by the APHA. White-coat percent significantly increased in h...
Early life jumping traits: Are they good proxies for success in show jumping competitions in Belgian warmblood horses? The main goal of the Belgian Warmblood horse studbook (BWP) is to breed successful competition horses, with emphasis on show jumping. However, competition results are only available later in life and competition traits are lowly heritable. Hence, the use of phenotypes that record performance-related traits at an early life stage could help increase genetic progress. In this study, we evaluated the potential of eleven linear scored early life jumping traits assessed during jumping in freedom (2-5 years old) or under the saddle (4-6 years old) as proxies for later success in show jumping com...
Additional evidence supports GRM6 p.Thr178Met as a cause of congenital stationary night blindness in three horse breeds. Congenital stationary night blindness (CSNB) is an ocular disorder characterized by nyctalopia. An autosomal recessive missense mutation in glutamate metabotropic receptor 6 (GRM6 c.533C>T, p.(Thr178Met)), called CSNB2, was previously identified in one Tennessee Walking Horse and predicted to reduce binding affinity of the neurotransmitter glutamate, impacting the retinal rod ON-bipolar cell signaling pathway. Thus, the first aim was to identify the allele frequency (AF) of CSNB2 in breeds with reported cases of CSNB and breeds closely related to the Tennessee Walking Horse. The second aim ...
The PTP1B Inhibitor Trodusquemine (MSI-1436) Improves Glucose Uptake in Equine Metabolic Syndrome Affected Liver through Anti-Inflammatory and Antifibrotic Activity. Hyperactivation of protein tyrosine phosphatase (PTP1B) has been associated with several metabolic malfunctions ranging from insulin resistance, metaflammation, lipotoxicity, and hyperglycaemia. Liver metabolism failure has been proposed as a core element in underlying endocrine disorders through persistent inflammation and highly fibrotic phenotype. Unassigned: In this study, the outcomes of PTP1B inhibition using trodusquemine (MSI-1436) on key equine metabolic syndrome (EMS)-related alterations including inflammation, fibrosis, and glucose uptake have been analyzed in liver explants collect...
Mesenchymal Stem Cells Isolated from Equine Hair Follicles Using a Method of Air-Liquid Interface. Equine mesenchymal stem cells (MSC) of various origins have been identified in horses, including MSCs from the bone marrow and adipose tissue. However, these stem cell sources are highly invasive in sampling, which thereby limits their clinical application in equine veterinary medicine. This study presents a novel method using an air-liquid interface to isolate stem cells from the hair follicle outer root sheath of the equine forehead skin. These stem cells cultured herewith showed high proliferation and asumed MSC phenotype by expressing MSC positive biomarkers (CD29, CD44 CD90) while not e...
Macrophage phenotype impacts in vitro equine intrasynovial deep digital flexor tenocyte matrix metalloproteinase gene expression and secretion. To investigate matrix metalloproteinase (MMP) and their inhibitors tissue inhibitor matrix metalloproteinase (TIMP) gene expression and secretion during equine deep digital flexor tendon (DDFT) tenocyte and macrophage (undifferentiated, proinflammatory, and regulatory) co-culture. Methods: Third passage DDF tenocytes and donor-matched macrophages differentiated from peripheral blood CD14+ monocytes from 5 healthy horses ages 9-11 years, euthanized for reasons unrelated to musculoskeletal conditions. Methods: Passage 3 DDT tenocyte aggregate cultures were co-cultured with undifferentiated (cont...
Pro-Inflammatory Cytokine Priming and Purification Method Modulate the Impact of Exosomes Derived from Equine Bone Marrow Mesenchymal Stromal Cells on Equine Articular Chondrocytes. Osteoarthritis (OA) is a widespread osteoarticular pathology characterized by progressive hyaline cartilage degradation, exposing horses to impaired well-being, premature career termination, alongside substantial financial losses for horse owners. Among the new therapeutic strategies for OA, using mesenchymal stromal cell (MSC)-derived exosomes (MSC-exos) appears to be a promising option for conveying MSC therapeutic potential, yet avoiding the limitations inherent to cell therapy. Here, we first purified and characterized exosomes from MSCs by membrane affinity capture (MAC) and size-exclusio...
A de novo 2.3 kb structural variant in MITF explains a novel splashed white phenotype in a Thoroughbred family. Splashed white in horses is characterized by extensive white patterning on the legs, face and abdomen and may be accompanied by deafness. To date, seven variants in microphthalmia-associated transcription factor (MITF) and two variants in Paired Box 3 (PAX3) have been identified to explain this phenotype. A splashed white Thoroughbred stallion, whose sire and dam were not patterned, was hypothesized to have a de novo variant leading to his white coat pattern. A whole-genome sequencing candidate gene approach identified two single nucleotide variants (SNVs) in SOX10, four SNVs in MITF and a 2.3...
Novel Genotype of Streptococcus dysgalactiae subsp. equisimilis Associated with Mastitis in an Arabian Filly: Genomic Approaches and Phenotypic Properties. Streptococcus dysgalactiae subsp. equisimilis (Sde) is a commensal bacterium of horses that causes opportunistic infections. The aim of the work was to study genotypic and phenotypic properties of the Sde strain related to equine neonatal mastitis. Sde was isolated from an 8 day-old filly and sequenced for genome analysis, antibiotic susceptibility tests and virulence factor (VF) assays. The Sde strain presented the novel emm-subtype stC839.12 and the novel multilocus-sequence type ST-670, which belonged to a specific equine genotype group. Although no specific genotypic mechanisms related to ...
Effect of pro-inflammatory cytokine priming and storage temperature of the mesenchymal stromal cell (MSC) secretome on equine articular chondrocytes. Osteoarthritis (OA) is an invalidating articular disease characterized by cartilage degradation and inflammatory events. In horses, OA is associated with up to 60% of lameness and leads to reduced animal welfare along with extensive economic losses; currently, there are no curative therapies to treat OA. The mesenchymal stromal cell (MSC) secretome exhibits anti-inflammatory properties, making it an attractive candidate for improving the management of OA. In this study, we determined the best storage conditions for conditioned media (CMs) and tested whether priming MSCs with cytokines can enh...
