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.
Villagómez DA, Lear TL, Chenier T, Lee S, McGee RB, Cahill J, Foster RA, Reyes E, St John E, King WA.We described the clinical, cytogenetic and molecular findings of 17 clinical equine cases presented for abnormal sexual development and infertility. Six horses with an enlarged clitoris had an XX, SRY-negative genotype, which displayed male-like behavior (adult individuals). Bilateral ovotestes were noted in 2 of those cases, while another case showed increased levels of circulating testosterone. Six horses with a female phenotype, including normal external genitalia, had an XY, SRY-negative genotype. These individuals had small gonads and an underdeveloped internal reproductive tract. Four ho...
Campana MG, Whitten CM, Edwards CJ, Stock F, Murphy AM, Binns MM, Barker GW, Bower MA.Historic DNA data have the potential to identify phenotypic information otherwise invisible in the historical, archaeological and palaeontological record. In order to determine whether a single nucleotide polymorphism typing protocol based on single based extension (SNaPshot™) could produce reliable phenotypic data from historic samples, we genotyped three coat colour markers for a sample of historic Thoroughbred horses for which both phenotypic and correct genotypic information were known from pedigree information in the General Stud Book. Experimental results were consistent with the pedig...
White SD, Bourdeau P.Hereditary equine regional dermal asthenia (HERDA) in Quarter Horses is an inherited degenerative skin disease. Initially reported as hyperelastosis cutis, HERDA has a phenotype of hyperextensible, fragile skin, with secondary seromas, haematomas, ulcers and scarring. It primarily affects the dorsal aspect of the body. An autosomal recessive mode of inheritance is considered likely, with affected horses more at risk to produce affected offspring. A mutation in cyclophilin B (PPIB) as a novel, causal candidate gene for HERDA has been described, and verified as segregating with carriers and affe...
Carrade DD, Owens SD, Galuppo LD, Vidal MA, Ferraro GL, Librach F, Buerchler S, Friedman MS, Walker NJ, Borjesson DL.The development of an allogeneic mesenchymal stem cell (MSC) product to treat equine disorders would be useful; however, there are limited in vivo safety data for horses. We hypothesized that the injection of self (autologous) and non-self (related allogeneic or allogeneic) MSC would not elicit significant alterations in physical examination, gait or synovial fluid parameters when injected into the joints of healthy horses. Methods: Sixteen healthy horses were used in this study. Group 1 consisted of foals (n = 6), group 2 consisted of their dams (n = 5) and group 3 consisted of half-siblings ...
Lanka S, Borst LB, Patterson SK, Maddox CW.The objective of the present investigation was to differentiate between strains of Streptococcus equi subspecies equi implicated in abscess formation in vaccinated horses. Streptococcus equi isolates recovered from clinical specimens associated with equine strangles cases submitted to the University of Illinois Veterinary Diagnostic Laboratory were compared with S. equi isolates representing at least 12 lots of a commercial modified live vaccine (MLV) to determine whether the isolates obtained from the abscesses were vaccine or wild type. Genotyping techniques evaluated included enterobacteria...
Schröder W, Klostermann A, Distl O.Intense selection for speed, endurance or pulling power in the domestic horse (Equus caballus) has resulted in a number of adaptive changes in the phenotype required for elite athletic performance. To date, studies in humans have revealed a large number of genes involved in elite athletic performance, but studies in horses are rare. The horse genome assembly and bioinformation tools for genome analyses have been used to compare human performance genes with their equine orthologues, both to retrieve pathways for these genes and to investigate their chromosomal distribution. In this review, 28 c...
Kuiper H, Blum N, Distl O.In a 1.5-year-old Oldenburg horse, a clitoris-like structure instead of a penis was identified in the prepuce. The external genital organs did not show any abnormalities at visual inspection except that exteriorization of the penis was not possible, not even under general anesthesia. The horse's owner observed a continuous dripping of urine and a tendency to mild colics beginning 2 weeks after birth. Testosterone concentration was 0.01 ng/ml and therefore under the threshold for geldings, and the horse did not respond to the application of gonadotropin-releasing hormone (GnRH). The inner genit...
Hackett CH, Flaminio MJ, Fortier LA.A long-term goal of mesenchymal progenitor cell (MPC) research is to identify cell-surface markers to facilitate MPC isolation. One reported MPC feature in humans and other species is lack of CD14 (lipopolysaccharide receptor) expression. The aim of this study was to evaluate CD14 as an MPC sorting marker. Our hypothesis was that cells negatively selected by CD14 expression would enrich MPC colony formation compared with unsorted and CD14-positive fractions. After validation of reagents, bone marrow aspirate was obtained from 12 horses. Fresh and cultured cells were analyzed by flow cytometry ...
Braun J, Hack A, Weis-Klemm M, Conrad S, Treml S, Kohler K, Walliser U, Skutella T, Aicher WK.To evaluate the proliferative behavior, telomere length, immunophenotype, and differentiation capacity of equine adipose tissue-derived mesenchymal stem cells (AT-MSCs). Methods: 6 adult racing horses treated for articular Injury but otherwise healthy. Methods: AT-MSCs were Isolated from horses and expanded In Dulbecco modified Eagle medium enriched with fetal bovine serum and antimicrobials. Expression of cell surface antigens and telomere length were Investigated via flow cytometry Differentiation of MSCs Into chondrocytes, osteoblasts, and adipocytes was Induced In vitro by specific stimuli...
Schroderus E, Ojala M.The aim of this study was to estimate genetic parameters for conformation measures and scores in the Finnhorse and the Standardbred foals presented in foal shows. Studied traits included height at withers and at croup, six subjectively evaluated conformation traits and overall grade. Data were from 10-year period (1995-2004) and consisted of 5821 Finnhorse foals (1-3 years old) with 7644 records and 2570 Standardbred foals (1-2 years old) with 2864 records. Variance components were estimated with REML - animal model using VCE4 program. The model included age class, year of judging, sex and...
Dallap Schaer BL, Aceto H, Rankin SC.Nosocomial salmonellosis is an important problem for large animal veterinary teaching hospitals (VTHs). Objective: To describe failure of an Infection Control Program (ICP) that resulted in an outbreak of salmonellosis caused by Salmonella Newport multidrug resistant (MDR)-AmpC at a large animal VTH. Methods: Sixty-one animals identified with the outbreak strain of Salmonella. Methods: Retrospective study: Data collected included signalment, presenting complaint, duration of hospitalization, discharge status, and financial information. Phenotypic and genotypic characterization was performed on...
Kaps M, Curik I, Baban M.Heterogeneity of variance of growth traits over age is a common issue in estimating genetic parameters and is addressed in this study by selecting appropriate variance structure models for additive genetic and environmental variances. Modeling and partitioning those variances connected with analyzing small data sets were demonstrated on Lipizzan horses. The following traits were analyzed: withers height, chest girth, and cannon bone circumference. The measurements were taken at birth, and at approximately 6, 12, 24, and 36 mo of age of 660 Lipizzan horses born in Croatia between 1948 and 2000....
Echeverría MG, Díaz S, Metz GE, Serena MS, Panei CJ, Nosetto E.Equine viral arteritis (EVA) is a contagious viral disease that frequently causes mild or subclinical infections in adult horses. Only one EAV serotype has been described. However, there are differences in antigenicity, pathogenicity and neutralization characteristics of virus field strains. The interaction of two viral proteins, GP5 and M, is critical for infectivity and amino acid changes in the GP5 sequences have an effect on the neutralizing phenotype, regardless the effects of other viral proteins. The objective of the present study was to evaluate the neutralization phenotypes of the 5 u...
Bellone RR, Forsyth G, Leeb T, Archer S, Sigurdsson S, Imsland F, Mauceli E, Engensteiner M, Bailey E, Sandmeyer L, Grahn B, Lindblad-Toh K, Wade CM.Leopard Complex spotting occurs in several breeds of horses and is caused by an incompletely dominant allele (LP). Homozygosity for LP is also associated with congenital stationary night blindness (CSNB) in Appaloosa horses. Previously, LP was mapped to a 6 cm region on ECA1 containing the candidate gene TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) and decreased expression of this gene, measured by qRT-PCR, was identified as the likely cause of both spotting and ocular phenotypes. This study describes investigations for a mutation causing or associated with the Le...
Mosher CM, Court MH.Pharmacogenomics is the study of the impact of genetic variation on drug effects, with the ultimate goal of achieving "personalised medicine". Since the completion of the Human Genome Project, great strides have been made towards the goal of personalised dosing of drugs in people, as exemplified by the development of gene-guided dosing of the anticoagulant drug, warfarin. Although the pharmacogenomics of domestic animals is still at an early stage of development, there is great potential for advances in the coming years as the direct result of complete genome sequences currently being derived ...
Laumen E, Doherr MG, Gerber V.The horse owner assessed respiratory signs index (HOARSI-1-4, healthy, mildly, moderately and severely affected, respectively) is based on owner-reported clinical history and has been used for the investigation of recurrent airway obstruction (RAO) genetics utilising large sample sizes. Reliable phenotype identification is of paramount importance in genetic studies. Owner reports of respiratory signs have shown good repeatability, but the agreement of HOARSI with an in-depth examination of the lower respiratory tract has not been investigated. Objective: To determine the correlation of HOARSI ...
Abbott Y, Leonard FC, Markey BK.This study involved the phenotypic and molecular characterization of a population of methicillin-resistant Staphylococcus aureus isolates from animals and from veterinary personnel in Ireland. Isolates from 77 animals (dogs, n=44; cats, n=4; horses, n=29) and from 28 veterinary personnel were characterized using their antimicrobial resistance profiles and pulsed-field gel electrophoresis patterns. In addition, a representative number of these isolates (n=52) were further analysed using spa-typing techniques. The results obtained identified the presence of three distinct clonal complexes, CC5, ...
Hill EW, Gu J, Eivers SS, Fonseca RG, McGivney BA, Govindarajan P, Orr N, Katz LM, MacHugh DE.Variants of the MSTN gene encoding myostatin are associated with muscle hypertrophy phenotypes in a range of mammalian species, most notably cattle, dogs, mice, and humans. Using a sample of registered Thoroughbred horses (n = 148), we have identified a novel MSTN sequence polymorphism that is strongly associated (g.66493737C>T, P = 4.85x10(-8)) with best race distance among elite racehorses (n = 79). This observation was independently validated (P = 1.91x10(-6)) in a resampled group of Thoroughbreds (n = 62) and in a cohort of Thoroughbreds (n = 37, P = 0.0047) produced by the same trainer...
Billington HE, McEwan NR.Although various combinations of parental coat colours can produce a Palomino foal, examination of records of the British Palomino Society suggest that many animals registered with the society resulted from matings which maximise the likelihood or even guarantee a Palomino foal. When show records were examined, it was clear that the colouration preferred by judges corresponds to that of the only pair-wise parental combination guaranteeing a Palomino foal.
Rieder S.Colour phenotypes may have played a major role during early domestication events and initial selection among domestic animal species. As coat colours mostly follow a relatively simple mode of Mendelian inheritance, they have been among the first traits to be systematically analysed at the molecular level. As a result of the number of genetic tools developed during the past decade, horse coat colour tests have been designed and are now commercially available for some of the basic phenotypes. These tests enable breeders to verify segregation within particular pedigrees, to select specific colour...
Magdesian KG, Williams DC, Aleman M, Lecouteur RA, Madigan JE.To evaluate deafness in American Paint Horses by phenotype, clinical findings, brainstem auditory-evoked responses (BAERs), and endothelin B receptor (EDNBR) genotype. Methods: Case series and case-control studies. Methods: 14 deaf American Paint Horses, 20 suspected-deaf American Paint Horses, and 13 nondeaf American Paint Horses and Pintos. Methods: Horses were categorized on the basis of coat color pattern and eye color. Testing for the EDNBR gene mutation (associated with overo lethal white foal syndrome) and BAERs was performed. Additional clinical findings were obtained from medical reco...
Kakoi H, Tozaki T, Nagata S, Gawahara H, Kijima-Suda I.In order to develop a genotyping method that can be used in the registration procedure for Thoroughbreds, we developed a method for simultaneously genotyping multiple coat colour genes on the basis of single nucleotide polymorphism typing by using the SNaPshot(TM) technique. This method enabled precise and reasonable detection of causal mutations; it was effective for genotyping of MC1R, ASIP, and SLC45A2 at the Extension (E), Agouti (A), Cream dilution (C) loci, and the possibility of identification of rare variants of MC1R, EDNRB and KIT at the E, Overo (O) and Sabino 1 (SB1) loci, respectiv...
Swinburne JE, Bogle H, Klukowska-Rötzler J, Drögemüller M, Leeb T, Temperton E, Dolf G, Gerber V.Recurrent airway obstruction (RAO), or heaves, is a naturally occurring asthma-like disease that is related to sensitisation and exposure to mouldy hay and has a familial basis with a complex mode of inheritance. A genome-wide scanning approach using two half-sibling families was taken in order to locate the chromosome regions that contribute to the inherited component of this condition in these families. Initially, a panel of 250 microsatellite markers, which were chosen as a well-spaced, polymorphic selection covering the 31 equine autosomes, was used to genotype the two half-sibling familie...
Posta J, Komlósi I, Mihók S.The aims of this study were to estimate phenotypic and genetic parameters for a range of traits in Hungarian Sport Horses, and to compare several methods of estimating breeding value (BV) in this breed. The analyses were based on the Hungarian Sport Horse Studbook, results of self-performance tests (SPTs) and show-jumping competition results. An SPT comprises subjective judgement of conformation traits, movement analysis traits and free-jumping performance, assessed via ordinal scores. Genetic parameters of SPTs were estimated with an animal model. Different measurements of the competition per...
Mérant C, Breathnach CC, Kohler K, Rashid C, Van Meter P, Horohov DW.Newborn foals are very susceptible to infections by opportunistic pathogens such as Rhodococcus equi. This susceptibility is thought to be due to the immaturity of their immune system, in particular their inability to produce interferon-gamma. This deficiency may result from an insufficiency in accessory signals. We therefore compared monocyte-derived dendritic cells (MoDC) from foals and from adult horses. CD172, MHC-I and MHC-II were generally expressed on more than 90% MoDC from foals and adults. CD1w2(+)CD86(+) cells tended to be less represented in 2-3-week-old foals than in adults. This ...
Kamalov AA, Gukhikh GT, Kirpatovskiĭ VI, Zaraĭskiĭ EI, Poltavtseva RA, Plotnikov EIu, Kudriavtsev IuV, Efremov EA, Obokhotov DA.The study of cell cultures enriched with stem and progenitor cells in the treatment of experimental hypergonadotropic hypogonadism was made on 30 white non-inbred rats with experimental cryptorchism who have undergone xenotransplantation of human fetal enriched cell cultures. Spermatogenic epithelium on histological sections was studied on day 14 and 28 after xenotransplantation with calculation of the spermatogenesis index. The fertility index was estimated for each of the groups. Transplantation of enriched cell cultures enhances efficacy of restoration of adequate germinogenic and spermatog...
Taylor SE, Vaughan-Thomas A, Clements DN, Pinchbeck G, Macrory LC, Smith RK, Clegg PD.There is a paucity of data regarding molecular markers that identify the phenotype of the tendon cell. This study aims to quantify gene expression markers that distinguish between tendon fibroblasts and other mesenchymal cells which may be used to investigate tenogenesis. Methods: Expression levels for 12 genes representative of musculoskeletal tissues, including the proposed tendon progenitor marker scleraxis, relative to validated reference genes, were evaluated in matched samples of equine tendon (harvested from the superficial digital flexor tendon), cartilage and bone using quantitative P...
McCue ME, Valberg SJ, Jackson M, Borgia L, Lucio M, Mickelson JR.In this study we examined a family of Quarter Horses with Polysaccharide Storage Myopathy (PSSM) with a dominant mutation in the skeletal muscle glycogen synthase (GYS1) gene. A subset of horses within this family had a more severe and occasionally fatal PSSM phenotype. The purpose of this study was to identify a modifying gene(s) for the severe clinical phenotype. A genetic association analysis was used to identify RYR1 as a candidate modifying gene. A rare, known equine RYR1 mutation, associated with malignant hyperthermia (MH), was found to segregate in this GYS1 PSSM family. Retrospective ...
Hassan AA, Ulbegi-Mohyla H, Kanbar T, Alber J, Lämmler C, Abdulmawjood A, Zschöck M, Weiss R.The present study was designed to characterize phenotypically and genotypically seven Arcanobacterium haemolyticum strains obtained from infections of six horses. All seven strains showed the cultural and biochemical properties typical of A. haemolyticum and were susceptible to most of the antibiotics tested. The species identification could be confirmed by amplification and sequencing of the 16S rRNA gene and the 16S-23S rRNA intergenic spacer region and by PCR amplification of species-specific parts of the gene encoding phospholipase D in A. haemolyticum. Use of the latter could possibly imp...
Mirams M, Tatarczuch L, Ahmed YA, Pagel CN, Jeffcott LB, Davies HM, Mackie EJ.Osteochondrosis is a condition involving defective endochondral ossification and retention of cartilage in subchondral bone. The pathophysiology of this condition is poorly characterized, but it has been proposed that the fundamental defect is failure of chondrocyte hypertrophy. The aim of the current study was to characterize phenotypic changes in chondrocytes associated with the initiation of osteochondrosis. Early lesions were induced in an equine model of osteochondrosis by feeding foals a high energy diet for 8 or 15 weeks. Lesions in articular-epiphyseal growth cartilage were examined hi...
Sá e Silva M, da Costa MM, de Avila Botton S, Barretta C, Groff AC, de Vargas AC.Strangles is an acute and contagious disease characterized by inflammation of the upper respiratory tract of horses. The etiological agent of strangles is the bacteria S. equi subsp. equi, which belongs to the Lancefield group C. Opportunistic agents from the same group are frequently isolated from horses with strangles and may induce mistaken diagnoses. Among the subspecies of S. equi, the phenotypic features are almost undistinguishable; however, the pathogenic potential is widely differentiated. The aim of this study was to characterize S. equi isolates obtained from clinical samples of str...
Velie BD, Smith PM, Fjordbakk CT, Solé M, Jäderkvist Fegraeus K, Rosengren MK, Røed KH, Ihler CF, Lindgren G, Strand E.Dynamic laryngeal collapse (DLC) associated with poll flexion is the most common disorder of the upper respiratory tract (URT) in the Norwegian-Swedish Coldblooded Trotter (NSCT). The disorder, which has also been diagnosed in other breeds of trotters and gaited horses, appears to be related to anatomic phenotypes and only occurs during poll flexion when the horse is exercised 'on the bit'. Objective: Identify genomic regions associated with DLC in the NSCT by combining a rigorous phenotyping protocol with genomic data from a high-density equine genotyping array. Methods: Prospective case/cont...
Morice P, Allano M, Provost C, Fairbrother JH, Gagnon CA, Sauvé F.Genomic characterization was conducted on 2 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from 2 horses hospitalized during an overlapping period of time and 2 methicillin-sensitive S. aureus (MSSA) strains isolated from 2 distinct horses. Phylogenetic proximity was traced and the genotypic and phenotypic characteristics of the antimicrobial resistance of the strains were compared. Whole genome sequencing of MRSA strains for this report was similar but differed from whole genome sequencing of MSSA strains. The MRSA strains were closely related, belonging to sequence type ...
Grigolo B, Desando G, Cavallo C, Zini N, Ghisu S, Facchini A.Association of biomaterials with autologous cells can provide a new generation of implantable devices for cartilage repair. An ideal scaffold should possess a preformed three-dimensional shape, fix the cells to the damaged area and prevent their migration into the articular cavity. Furthermore, the constructs should have sufficient mechanical strength to facilitate handling in a clinical setting and stimulate the uniform spreading of cells and a phenotype re-differentiation process. The aim of this study was to verify the ability of an equine collagen membrane to support the growth of human ch...
Chapard L, Van Thillo A, Meyermans R, Gorssen W, Buys N, Janssens S.Show jumping is one of the most popular disciplines in the horse sector, which makes success in show jumping competitions an important breeding goal for many studbooks. Therefore, the genetic evaluation of show jumping performance is of major interest and this is the case for two Belgian Warmblood studbooks: the Belgian Warmblood horse and Zangersheide. In this study, first an improved phenotype for show jumping performance was developed, i.e. adjusted fence height based on a new non-arbitrary method to scale ranking and competition level, which are two major components of success in competiti...
Ryder OA, Sparkes RS, Sparkes MC, Clegg JB.1. Through the use of isoelectric focusing and peptide analysis, the hemoglobins of Przewalski's horse. Equus przewalskii and the domestic horse, E. caballus have been compared. 2. Przewalski's horses have two separate alpha-globin chain polymorphisms similar to domestic horses. Each hemoglobin phenotype could be accurately determined by isoelectric focusing. 3. Confirmation of the electrofocusing hemoglobin determinations was made by comparison to amino acid composition analyses of purified tryptic peptides and by analysis of the rare hemoglobins phenotypes observed in a family of Norwegian t...
Alizadeh AH, Briah R, Villagomez DAF, King WA, Koch TG.The aim of the present work was to determine proliferation capacity, immunophenotype and genome integrity of mesenchymal stromal cells (MSCs) from horse umbilical cord blood (UCB) at passage stage 5 and 10. Passage 4 cryopreserved UCB-MSCs from six unrelated donors were evaluated. Immunophenotypic analysis of UCB-MSC revealed a cell identity consistent with equine MSC phenotype by high expression of CD90, CD44, CD29, and very low expression of CD4, CD11a/18, CD73, and MHC class I and II antigens. Proliferative differences were noted among the UCB-MSC cultures. UCB-MSCs karyotype characteristic...
Stock KF, Distl O, Hoeschele I.Requirements for successful implementation of multivariate animal threshold models including phenotypic and genotypic information are not known yet. Here simulated horse data were used to investigate the properties of multivariate estimators of genetic parameters for categorical, continuous and molecular genetic data in the context of important radiological health traits using mixed linear-threshold animal models via Gibbs sampling. The simulated pedigree comprised 7 generations and 40000 animals per generation. Additive genetic values, residuals and fixed effects for one continuous trait and ...
Esdaile E, Kallenberg A, Avila F, Bellone RR.Coat color is a trait of economic significance in horses. Variants in seven genes have been documented to cause white patterning in horses. Of the 34 variants that have been identified in KIT proto-oncogene, receptor tyrosine kinase (), 27 have only been reported in a single individual or family and thus not all are routinely offered for genetic testing. Therefore, to enable proper use of marker-assisted selection, determining breed specificity for these alleles is warranted. Screening 19 unregistered all-white Shetland ponies for 16 white patterning markers identified 14 individuals whose phe...
Toth Z, Kaps M, Sölkner J, Bodo I, Curik I.The aim of this study was to estimate genetic parameters for coat color in horses. Besides defining coat color classes (gray, chestnut, bay, and black), the phenotypes were also measured quantitatively according to standardized international procedures (Commission Internationale de l'Eclairage L*, a*, b*), where L* describes lightness, a* describes color saturation from red to green, and b* describes color saturation from yellow to blue. The total color saturation was derived from a* and b* and referred to as Chroma. A total of 294 horses from the breeds Lipizzan, Nonius, Arabian Pure Bred, Sh...
Vostry L, Vostra-Vydrova H, Citek J, Gorjanc G, Curik I.Inbreeding depression is the reduction of performance caused by mating of close relatives. In livestock populations, inbreeding depression has been traditionally estimated by regression of phenotypes on pedigree inbreeding coefficients. This estimation can be improved by utilising genomic inbreeding coefficients. Here we estimate inbreeding depression for insect bite hypersensitivity (IBH) prevalence, the most common allergic horse disease worldwide, in Old Kladruber horse. In a deep pedigree with 3214 horses (187 genotyped), we used a generalised linear mixed model with IBH phenotype from 558...
Marycz K, Pielok A, Kornicka-Garbowska K.Laminitis is a life threating, extremely painful and frequently recurrent disease of horses which affects hoof structure. It results from the disruption of blood flow to the laminae, contributing to laminitis and in severe separation of bone from the hoof capsule. Still, the pathophysiology of the disease remains unclear, mainly due to its complexity. In the light of the presented data, in the extremally difficult process of tissue structure restoration after disruption, a novel type of progenitor cells may be involved. Herein, we isolated and performed the initial characterization of stem pro...
Clark BL, Bamford NJ, Stewart AJ, McCue ME, Rendahl A, Bailey SR, Bertin FR, Norton EM.The HMGA2:c.83G>A variant was identified in Welsh ponies having pleiotropic effects on height and insulin concentration. Objective: Determine whether the HMGA2:c.83G>A variant is associated with decreased height and higher basal insulin concentrations across pony breeds. Methods: Two hundred thirty-six ponies across 6 breeds. Methods: Cross-sectional study. Ponies were genotyped for the HMGA2:c.83G>A variant and phenotyped for height and basal insulin concentrations. Stepwise regression was performed for model analysis using a linear regression model for height and mixed linear model ...
Naylor RJ, Livesey L, Schumacher J, Henke N, Massey C, Brock KV, Fernandez-Fuente M, Piercy RJ.Equine type 1 polysaccharide storage myopathy (PSSM1), a common glycogenosis associated with an R309H founder mutation in the glycogen synthase 1 gene (GYS1), shares pathological features with several human myopathies. In common with related human disorders, the pathogenesis remains unclear in particular, the marked phenotypic variability between affected animals. Given that affected animals accumulate glycogen and alpha-crystalline polysaccharide within their muscles, it is possible that physical disruption associated with the presence of this material could exacerbate the phenotype. The aim ...
Bustos CP, Retamar G, Leiva R, Frosth S, Ivanissevich A, Demarchi ME, Walsh S, Frykberg L, Guss B, Mesplet M, Waller A.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 ...
Braend M.During the routine parentage control of Norwegian Trotter horses with 10 000 parent offspring combinations two irregular transmissions of Pr alleles were found. The allele products were provisionally named D1 and D2. They appeared in two stallions which were typed as D1I and D2N respectively. The first stallion transmitted PrD1 to seven out of 10 offspring and the second stallion PrD2 to two of four offspring. Photographs of seven new Pr phenotypes are presented.
Tanaka Y, Adilbish A, Koyama K, Bayasgalan MO, Horiuchi N, Uranbileg N, Watanabe K, Purevdorj B, Gurdorj S, Banzragch B, Badgar B, Suganuma K....Dourine is a deadly protozoan disease in equids caused by infection with Trypanosoma equiperdum. Neurological signs in the later stage of infection may be caused by peripheral polyneuritis and related axonal degeneration. This neuritis involves T lymphocytes, B lymphocytes, and macrophages, and is observed in cases without obvious neurological signs. However, the pathogenesis of neuritis remains unclear. We identified M2 macrophages and CD8 T cells as the predominant phenotypes in neuritis of dourine-affected horses with or without neurological signs. In contrast, the populations of M1 macroph...
Olsen HF, Klemetsdal G, Odegård J, Arnason T.There have been several approaches to the estimation of breeding values of performance in trotters, and the objective of this study was to validate different alternatives for genetic evaluation of racing performance in the North Swedish and Norwegian cold-blooded trotters. The current bivariate approach with the traits racing status (RACE) and earnings (EARN) was compared with a threshold-linear animal model and the univariate alternative with the performance trait only. The models were compared based on cross-validation of standardized earnings, using mean-squared errors of prediction (MSEP) ...
Müller V, Moraes BDSS, Carvalho IR, Wendt CG, Patten RD, Nogueira CEW.The aim of this study was to estimate the genetic parameters for the morphometric measurements of withers height (WH), thoracic circumference (TC) and cannon bone circumference (CBC) of Criollo horses, stratified for maternal and paternal effects. Statistical genetic design of factor crossings was used to evaluate the offspring of full siblings and half-siblings. Fifty stallions were selected (n = 50) who had been crossed with six mares each (n = 6), to provide 300 parental pairings in which two offspring were born per mare (n = 600). WH in females and TC in males were highly influenced ...
Ramos S, Pinto A, Crespo J, Marques JP, Bettencourt E, Gama LT, Monteiro S.Osteochondrosis (osteochondritis dissecans), OC(D), is an important joint disorder that has been studied through the years in different breeds but, to our knowledge, there are no reports of its prevalence in Lusitano horses. The aim of this study was to assess the prevalence of OC(D) in Lusitanos, define the characteristics of the disorder in this breed and compare with Spanish Purebred horses. This is a retrospective study that analysed the radiographs from the metacarpometatarsophalangeal, tarsocrural and femoropatellar joints that were taken in 302 Lusitano horses (1-12 years; obtained from...
Gmel AI, Brem G, Neuditschko M.Conformation traits are important selection criteria in equine breeding, as they describe the exterior aspects of the horse (height, joint angles, shape). However, the genetic architecture of conformation is not well understood, as data of these traits mainly consist of subjective evaluation scores. Here, we performed genome-wide association studies on two-dimensional shape data of Lipizzan horses. Based on this data, we identified significant quantitative trait loci (QTL) associated with cresty neck on equine chromosome (ECA)16 within the MAGI1 gene, and with type, hereby differentiating heav...
McFadden A, Martin K, Foster G, Vierra M, Lundquist EW, Everts RE, Martin E, Volz E, McLoone K, Brooks SA, Lafayette C.Mutations in KIT, a gene that influences melanoblast migration and pigmentation, often result in mammalian white spotting. As of February 2023, over 30 KIT variants associated with white spotting were documented in Equus caballus (horse). Here we report an association of increased white spotting on the skin and coat with a variant in the 5'UTR of KIT (rs1149701677: g.79,618,649A>C). Horses possessing at least one alternate allele demonstrate phenotypic characteristics similar to other KIT mutations: clear borders around unpigmented regions on the body, face, and limbs. Using a quantitative ...
Ewart SL, Robinson NE.This review highlights the critical importance of phenotype definition in the understanding of the pathogenesis of respiratory disease in horses. The general approach to genetic studies is discussed and comparative studies of recurrent airway obstruction (RAO) conditions, such as asthma, described in the context of learning more about equivalent equine conditions. The availability of methods to study genetic tests have previously relied on DNA sequence knowledge from man, laboratory and domesticated animals, but recent data from the horse genome sequence are now available. This should facilita...
McBride SD, Roberts K, Hemmings AJ, Ninomiya S, Parker MO.Stress and genotype elicit changes in impulse control in a range of species that are attributable to adaptations in both the central and peripheral nervous system. We examined aspects of this mechanism in the horse by assessing the effect of a dopamine receptor genotype (DRD4) and central dopaminergic tone (measured via spontaneous blink rate [SBR] and behavioral initiation rate [BIR]), on measures of impulsivity, compulsivity (3-choice serial reaction time task) and sympathetic/ parasympathetic system balance (heart rate variability [HRV]). Genotype did not have a significant effect on any of...
Cooper HE, Bowlby C, Long S, Durgam SS.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...
Esdaile E, Knickelbein KE, Donnelly CG, Ferneding M, Motta MJ, Story BD, Avila F, Finno CJ, Gilger BC, Sandmeyer L, Thomasy S, Bellone RR.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 ...
Chapard L, Meyermans R, Gorssen W, Hooyberghs K, Meurrens I, De Smet S, Buys N, Janssens S.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...
Weckman MJ, Karikoski NP, Raekallio MR, Box JR, Kvist L.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...
Santiviparat S, Swangchan-Uthai T, Stout TAE, Buranapraditkun S, Setthawong P, Taephatthanasagon T, Rodprasert W, Sawangmake C, Tharasanit T.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...
Azcona F, Karlau A, Trigo P, Molina A, Demyda-Peyrás S.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...
