Equine Studies encompasses the scientific exploration and analysis of various aspects related to horses, including their physiology, behavior, genetics, nutrition, and management. This interdisciplinary field integrates knowledge from veterinary medicine, animal science, and equine management to enhance understanding of horse health and welfare. Topics within equine studies often include the study of equine anatomy, disease prevention, breeding practices, and performance optimization. Researchers and scholars contribute to this field by conducting experiments, field studies, and reviews that provide insights into improving equine care and management practices. This page compiles peer-reviewed research studies and scholarly articles that investigate diverse areas within equine studies, offering comprehensive insights into the complexities of horse biology and management.
Vos JH, Deleu SA, Heling W, de Vries AR, Zeeuwen AA.The most relevant results of a written questionnaire among veterinarians in the Netherlands are presented and discussed. The inquiry was performed by MarketResponse Nederland BV. The objective was to get an overview of the current perception and the future view of the profession. The response was 37%. Most respondents (66%) were practitioners, 7% were active in research or teaching institutions, 5% were governmental employees, 5% were employed in industry, and 17% did not belong to any of these categories (retired, unemployed etc.). Forty-seven per cent of the veterinarians practised mainly sm...
Muylle S, Simoens P, Lauwers H.This paper gives an anatomical overview of the dentinal structure in equine incisor teeth with special reference to the three-dimensional organization, the number and the diameter of the dentinal tubules. The spatial arrangement of equine dentine was examined by scanning electron microscopy of occlusal surfaces and longitudinally fractured teeth and by light microscopy of both decalcified and ground sections. The dentinal tubules of the peripherally situated primary dentine were directly continuous with those of the circumpulpal secondary dentine. The tubules had numerous side branches along t...
Cameron EZ, Linklater WL.The Trivers-Willard hypothesis (TWH) predicts that a mother will treat a son or daughter differently depending on her ability to invest and the impact of her investment on offspring reproductive success. Although many studies have investigated the hypothesis, few have definitively supported or refuted it because of confounding factors or an inappropriate level of analysis. We studied maternal investment in sons and daughters in feral horses, Equus caballus, which meet the assumptions of the TWH with a minimum of confounding variables. Population level analyses revealed no differences in matern...
Hallebeek JM, van Doorn DA, Beynen AC.In horses that exercise intensively (for example, event horses in training) the intake and energy requirements were compared on the basis of a diet record and estimates of energy required for exercise. Daily net energy intake over a 7 days period was on average 30% (n = 15) higher than the net energy requirement. Since the horses had a constant body weight, and thus were in energy balance, the energy intake was overestimated and/or the energy requirement was underestimated. The intake of digestible protein was 92% higher than the protein requirement. This study illustrates the problems concern...
Brinsko SP, Crockett EC, Squires EL.The objective of this study was to determine if centrifugation and partial removal of seminal plasma would improve spermatozoal motility in semen from stallions whose whole ejaculates have poor tolerance to cooling and storage. Stallions were divided into two groups (n = 5/group) based on the ability of their extended semen to maintain spermatozoal motility after cooling and storage. Group 1 stallions ("good coolers") produced semen in which progressive spermatozoal motility after 24 h of cooling and storage was reduced by < or = 30% of progressive motility prior to storage. Group 2 stallions ...
Bowers J, Slocombe R.To determine commonly used girth tensions in Thoroughbred racehorses in the Melbourne metropolitan area. Methods: A prospective industry survey. Methods: Strappers were instructed to tension girths, using the same saddle, under-saddle packing and girth, sufficiently to hold the saddle for racing. These tensions were continuously recorded by an in-line load cell in the girth. Seventeen strappers from five stables participated in the study, which was conducted on 91 horses. Results: Resting girth tensions varied considerably. The mean tension on inhalation was 13 +/- 0.4 kg. Male strappers recor...
Gravance CG, Garner DL, Baumber J, Ball BA.The fluorescent carbocyanine dye, JC-1, labels mitochondria with high membrane potential orange and mitochondria with low membrane potential green. Evaluation of mitochondrial membrane potential with JC-1 has been used in a variety of cell types, including bull spermatozoa; however, JC-1 staining has not yet been reported for equine spermatozoa. The aim of this study was to apply JC-1 staining and assessment by flow cytometry or a fluorescence microplate reader for evaluation of mitochondrial function of equine spermatozoa. Six ejaculates from four stallions were collected and centrifuged thro...
Eagle RC, Tortonese DJ.Little is known about the neuroendocrine control of fertility in the horse. In this species, unusual features characterize the normal estrous cycle such as a prolonged preovulatory LH surge during the follicular phase and a distinctive FSH surge during the midluteal phase. This study investigated the distribution and hormonal identity of gonadotrophs in the pars distalis (PD) and pars tuberalis (PT) of the equine pituitary gland as possible morphological bases for the referred unusual endocrine characteristics. In addition, the proportion of gonadotrophs in relation to other pituitary cell typ...
Houpt KA, Eggleston A, Kunkle K, Houpt TR.Six pregnant mares were used to determine what level of water restriction causes physiological and/or behavioural changes indicative of stress. Nonlegume hay was fed ad libitum. During the first week of restriction, 5 l water/100 kg bwt was available, during the second week 4 l/100 kg bwt and, during the third week, 3 l/100 kg bwt. Ad libitum water intake was 6.9 l/100 kg bwt; at 3 l/100 kg bwt water intake was 42% of this. Daily hay intake fell significantly with increasing water restriction from 12.9 +/- 0.75 kg to 8.3 +/- 0.54 kg; bodyweight fell significantly for a total loss of 48.5 +/- 8...
Katz LM, Bayly WM, Roeder MJ, Kingston JK, Hines MT.To establish maximum oxygen consumption VO2max) in ponies of different body weights, characterize the effects of training of short duration on VO2max, and compare these effects to those of similarly trained Thoroughbreds. Methods: 5 small ponies, 4 mid-sized ponies, and 6 Thoroughbreds. Methods: All horses were trained for 4 weeks. Horses were trained every other day for 10 minutes on a 10% incline at a combination of speeds equated with 40, 60, 80, and 100% of VO2max. At the beginning and end of the training program, each horse performed a standard incremental exercise test in which VO2max wa...
Kumar P, Timoney JF, Southgate HH, Sheoran AS.The nasal turbinates of 5 young horses were studied by light and scanning electron-microscopy. Stratified cuboidal epithelium lined the rostral part of the dorsal and ventral nasal turbinates of the vestibular region. The polyangular microvillus cells of this region were separated by linear depressions. The mid and caudal parts of the dorsal and ventral nasal turbinates and the rostral part of the ethmoturbinates were lined by pseudostratified columnar ciliated respiratory epithelium. Numerous cilia with dilated blebs on the ciliated cells concealed adjacent non-ciliated supporting cells and g...
Chae JS, Pusterla N, Johnson E, Derock E, Lawler SP, Madigan JE.We provide evidence of Ehrlichia risticii Holland, the agent of Potomac horse fever, in trematode stages found in aquatic insects collected from a pasture stream in northern California, using nested polymerase chain reaction (PCR) amplification and sequence analyses of the 16S rRNA, 51 kDa major antigen and groEL heat shock protein genes. E. risticii was detected in metacercariae found in the immatures and adults of the following insects: caddisflies (Trichoptera), mayflies (Ephemeroptera), damselflies (Odonata, Zygoptera), dragonflies (Odonata, Anisoptera), and stoneflies (Plecoptera). The pr...
Deriusheva SE, Loginova IuA, Chiriaeva OG, Iasinetskaia NI, Efimov AM.Restriction endonuclease in situ digestion of metaphase chromosomes gives an opportunity to reveal strips with different structure within GC-rich pericentric heterochromatin of the domestic horse and the wild Przewalski horse. Blocks of heterochromatin, which are insensitive to HaeIII and brightly stained with chromomycin A3 after restriction enzyme digestion, are localized on the border with euchromatin in the majority of chromosomes of Equus caballus and E. przewalskii. In contrast to chromosome 5 of E. caballus, acrocentric chromosomes of E. prezewalskii which are homologous to this chromos...
Brinsko SP, Rowan KR, Varner DD, Blanchard TL.This study was conducted to compare the cooling rates and storage temperatures within equine semen transport containers exposed to different ambient temperatures, and to evaluate the ability of these containers to preserve spermatozoal motility following 24 h of storage under these conditions. In Experiment 1, nonfat dried milk solids, glucose, sucrose, equine semen extender was divided into seven 40-mL aliquots and loaded into seven different semen transport containers: Equitainer I, Equitainer II, Equitainer III, ExpectaFoal, Bio-Flite, Lane STS, and Equine Express. After containers were loa...
Fitzgerald BP, Davison LA, McManus CJ.In seasonally breeding species photoperiodic information is thought to be conveyed to the reproductive and prolactin axis via changes in circulating concentrations of melatonin. For some species, a constant melatonin stimulus is perceived as a short day, whereas in others no photoperiodic information is provided. In the mare, a preliminary study demonstrated that constant administration of melatonin did not modify prolactin secretion, suggesting that this treatment regimen failed to provide photoperiodic information. To further investigate this proposal and to investigate an alternative explan...
Cooper JJ, McDonald L, Mills DS.Stabled horses commonly perform stereotypic patterns of weaving, where the horse shifts its weight from side to side often swinging its head. Ten warm-blood types, of which five were known to reliably weave, were housed in similar 12x12 ft wooden loose boxes in a single stable block surrounding a courtyard. Each horse was exposed to each of five stable designs. These were: the conventional front top-half of the door open only with a view of the stable courtyard (F); front half-door open and a similar half-door open at the back of the stable with a view to the surrounding fields (FB); back open...
Sharp DC.This paper will discuss development of the equine conceptus, especially from the perspective of the maternal environment in which it develops and to which it has considerable influence.
McDonnell SM.Based on observational studies comparing social organization and reproductive behavior of equids breeding under feral, semi-feral, and domestic conditions, a series of comparisons and findings on reproductive physiology and behavior are presented. Simple changes in management and handling of mares and stallions that can improve reproductive efficiency and fertility or that can overcome specific breeding problems are discussed.
Sinclair SE, McKinney S, Glenny RW, Bernard SL, Hlastala MP.We determined the changes in fractal dimensions and spatial correlations of regional pulmonary blood flow with increasing exercise in race horses (n = 4) by using 15-microm fluorescent microspheres. Fluorescence was measured to quantitate regional blood to 1.3-cm(3) samples (n = 1,621-2,503). Perfusion distributions were characterized with fractal dimensions (a measure of spatial variability) and spatial correlations. On average, the fractal dimension decreased with exercise (trot 1.216 to gallop 1.173; P < 0. 05) despite a variable fractal dimension at rest. Spatial correlation of flow to ...
Munroe G.Over 80 per cent of 169 neonatal thoroughbred foals had some part of the hyaloid artery present bilaterally and its degree of completeness, colour and character was statistically symmetrical. The complete artery was present in over 60 per cent of the foals. The incidence of the hyaloid artery and its completeness, colour and character were related to the age of the foal. The hyaloid system atrophies in the early stages of the neonatal period and generally its presence did not cause any significant ocular problems. The presence and morphology of the posterior pupillary membrane was highly corre...
Schramme MC, Boswell JC, Hamhougias K, Toulson K, Viitanen M.Numerous different techniques for injection of the navicular bursa have been described but there is little conformity between these descriptions. A literature review was performed and techniques for injection of the navicular bursa were categorised into 5 approaches. This study was performed to evaluate the reproducibility of each technique and to assess which technique was consistently most successful. Five inexperienced operators performed each technique on 5 cadaver forelimbs. Once a needle had been placed, a radiograph was taken to confirm placement was in accordance with the description o...
Pfeiffer CJ, Levin M, Lopes MA.This investigation examined primarily epidermal specializations of the adult horse tongue by light, scanning and transmission electron microscopy. Samples were collected from seven regions of the normal tongue of various breeds of horse. The filiform papillae, present on the dorsal and lateral aspects but not the ventral aspect of the tongue, were short, slender and finger-like structures with variable-shaped terminae. The epidermal thickness and height of dermal ridges were reduced on fungiform and vallate papillae, but tissue architecture and keratinocyte ultrastructure of most of the lingua...
Moser K, Banse H.The objectives of this study were to compare the insulin and glucose responses of horses to 2 formulations of corn syrup, [Karo Light (Karo) available in the United States, and Crown Lily White (Crown), available in Canada]. Horses were evaluated under both fed ( = 14) and fasted ( = 10) conditions. Using a randomized crossover design, each horse underwent an oral sugar test using Karo or Crown syrup. There were no significant differences in insulin or glucose time of maximum concentration (T), maximum concentration (C), or area under the curve (AUC) or in insulin or glucose concentrations at ...
Makowiecki D, Chudziak W, Szczepanik P, Janeczek M, Pasicka E.Knowledge about horses from early medieval (10th-13th c.) Poland has been largely based on historical and archaeological data. Archaeozoological information has only been used to a limited extent. Therefore, this article aims to present the current state of knowledge on this subject, drawing on archaeozoological data from studies of horse bones. Apart from confirming earlier reflections regarding the sacred significance of the horse, additional information was obtained about specific individuals who were the subject of magical treatments. It turned out that sites with horse skeletons and skull...
Becker AC, Stock KF, Distl O.Detailed movement evaluations of warmblood foals and mares were performed in connection with regular breeding events of the Oldenburg horse breeding societies in 2009 and 2010. Unfavourable movement characteristics considered indicative for impaired balance were noted by a special judge (SJ) and the regular judges of the breeding events (RJ) and served as the basis for definition of new movement traits. Detailed movement information on 3374 foals and 2844 mares showed that more severe findings like irregular motion pattern in hind legs or irregularity in general motion pattern occurred only sp...
Earley ET, Reiswig JD.Odontoplasty (floating and occlusal equilibration) is the most commonly performed procedure in equine dentistry. From an anatomic perspective, an irregular occlusal surface, prominent cingula, transverse ridges, and enamel points all contribute to the function, form, and longevity of the equine cheek tooth. With limited reserve crown available and an average functional life range between 18 and 25 years, removal of tooth structure should be conservative. The authors consider a quality oral examination to be the most important dental procedure performed in the horse. Individual tooth evaluatio...
Pelletier N, Leith DE.Horses have high mean pulmonary artery pressure (Ppa) both at rest and during exercise (approximately 30 and > or = 80 mmHg, respectively). The mechanisms are unknown. To see if hypoxic pulmonary vasoconstriction (HPV) plays a role, we compared pulmonary artery pressure-flow (Ppa-Q) curves when inspired O2 fraction (FIO2) was 0.16, 0.21, and 0.30, in 5 normal Thoroughbred horses standing quietly and while galloping at 10 and 14 m/sec on a level treadmill. We calculated O2 consumption (VO2) from measurements of respired gas composition and flow, and calculated Q from VO2 and measurements of ...
Smith S, Yohe LR, Solounias N.It has been recognized as early as the Victorian era that the apex of the distal phalanx has a distinct embryological development from the main shaft of the distal phalanx. Recent studies in regenerative medicine have placed an emphasis on the role of the apex of the distal phalanx in bone regrowth. Despite knowledge about the unique aspects of the distal phalanx, all phalanges are often treated as equivalent. Our morphological study reiterates and highlights the special anatomical and embryological properties of the apex of the distal phalanx, and names the apex "the bony cap" to distinguish ...
Beachler TM, Scott Bailey C, Gracz HS, Morgan DR, Von Dollen KA, Ellis KE, Gadsby JE, Lyle SK.The amniotic and allantoic fluid compartments in the mare serve essential roles throughout pregnancy and parturition. Although the global metabolomic profile of amniotic fluid in women has been extensively characterized, current data for equine fetal fluids are limited. Therefore, the goal of this study was to characterize the global metabolomic profile of equine allantoic and amniotic fluid through nuclear magnetic resonance spectroscopy. Fetal fluids were collected between 270 and 295 days of gestation from 12 pregnancies through ultrasound-guided transabdominal puncture. A total of 24 samp...
Bowers J, Slocombe RF, Sides RH, Bayly WM, Kingston JK.To determine the effect of girth construction and tension on respiratory mechanics and gas exchange during supramaximal treadmill exercise in horses. Methods: Six healthy detrained Thoroughbred horses were exercised on a treadmill inclined at 10% at 110% VO2max. Horses were instrumented for respiratory mechanics and gas exchange studies, and data were recorded during incremental exercise tests. The animals were exercised for 2 min at 40% VO2max, and samples and measurements were collected at 1 min 45 sec. After 2 min, speed was increased to that estimated at 110% VO2max and data was collected ...
Saltiel A, Calderon A, Garcia N, Hurley DP.Ovarian activity, as measured by the presence of small (10-15 mm diam.), medium (15-30 mm) and large (greater than 30 mm) follicles, corpora haemorrhagica and corpora lutea (CL), was determined in a total of 3584 ovaries during 1 year using post-mortem specimens. There were significant correlations of the incidence of ovulated follicles (ovulations), large and medium follicles (P less than 0 . 001) and of the mean number of small follicles (P less than 0 . 05) per mare with respect to season. The yearly averages of ovulated, large and medium follicles were 30 . 1, 13 . 9 and 73 . 9%, respectiv...
Al-Jaru A, Goodwin W, Skidmore J, Raudsepp T, Khazanehdari K.Chromosome configurations and chiasma frequency during the metaphase I stage of spermatogenesis in the male horse are characterized in this work. The genome-wide frequency and distribution of chiasmata was detected as 49.45 ± 2.07 for 14 fertile stallions. All X and Y chromosomes shared a single chiasma at their pseudoautosomal region, while 1-4 chiasmata were observed in autosomal chromosomes. The chiasma frequency and distribution were further studied for 8 different bivalents identified by FISH in 5 fertile stallions. Genetic length was calculated from chiasmata data for the whole genome a...
Hiraga A, Hobo S, Birks EK, Takahashi T, Hada T, Smith BL, Carr EA, Pascoe JR, Jones JH.Three mature Thoroughbred horses were prepared surgically with ultrasonic sonomicrometer crystals affixed to their ventricular pericardia. Signals from crystals recorded dimensions of axes across the left ventricle. Cubic algorithms were fitted to dimensional data to generate volume estimates that matched stroke volumes simultaneously measured using the Fick principle. As horses stood at rest or exercised at various intensities (approx 7, 12, 24, 47 and 100% maximal rate of O2 consumption VO2max[), left ventricular dimensions were recorded and 20 consecutive diastolic and systolic volumes calc...
Dovc P, Susnik S, Snoj A.Management of breeding- and free-living populations, traditionally based on phenotypic traits, relays more and more on availability of reliable information about the basic population genetic parameters as heterozygosity, mean number of alleles per locus, percentage of polymorphic loci, population structuring, genetic distances and others. Therefore, the application of molecular markers, revealing a great deal of phenotypically hidden information, becomes inevitable for population analysis. Conservation geneticists use this information for implementation of appropriate management policies. Appl...
Ginther OJ, Domingues RR, Dangudubiyyam SV, Araujo ER.Diameter deviation or follicle selection during a follicular wave begins with continuous growth rate of F1 (dominant or selected follicle; DF) and decreasing growth rate of F2 (largest subordinate). Intraovarian patterns based on presence or absence of the DF and CL are DF-CL, DF, CL, and devoid (neither DF nor CL). The DF and CL relationships in a pair of ovaries are ipsilateral (DF-CL pattern and devoid pattern) and contralateral (DF pattern and CL pattern). The effects of patterns and relationships on F1, F2, and FSH during deviation were determined in 21 mares. Diameters of F1 and F2 at ex...
Sato F, Tanabe T, Murase H, Tominari M, Kawai M.Global positioning system (GPS) units are now lightweight and compact. They have proven useful for analyzing the behavioral characteristics of horses in pastures. Because the GPS records data in latitude and longitude, it may be feasible to calculate the distance between GPS units. The present study aimed to confirm the applicability of GPS units in behavioral studies on horses. For this, we analyzed the accuracy of the distances calculated from GPS units using Hubeny's distance formula and of the monthly changes in interindividual distances obtained from GPS units worn by Thoroughbred dams an...
Arabian AK, Lanovaz JL, Clayton HM.Determination of net joint moments and powers requires accurate measurements of mass and centre of mass (COM) for the limb segments. The objective of this research was to develop regression equations for calculating mass and COM of the hoof segment that are applicable over a wide range of hoof morphologies. Ninety-one hooves (mean +/- s.d. 0.99 +/- 0.50 kg) were weighed and the 3-dimensional COM determined using a mass balance technique. Ten morphological variables were measured and used as independent variables in linear regressions with dependent variables of mass and centre of mass. The reg...
Schulman ML, Marlow CH, Nurton JP.The data and an analysis of the statistical summaries from the 'Return of Mares' of the General Stud Book of The Jockey Club of Southern Africa from 1975-1999 are presented. The total number of mares covered per season ranged from 7393 (1992) to 5180 (1995). The total living produce in the period surveyed was 95 317 foals. The categories of data examined include: the total number of mares covered per season; the total numbers and percentage of their living produce; the total numbers and percentage dead produce, 'slips' and foals born dead, barren and 'no return' mares; and the total number of ...
Logan AA, Snyder AJ, Nielsen BD.The effects of gait and diameter have been studied independently, but rarely together in equine circular exercise studies. This study aimed to determine the impact of diameter (10-m or 15-m) at various gaits (walk, trot, and canter) on stride frequency or forelimb stance duration. Nine mature horses were outfitted with Tekscan™ Hoof Sensors on their forelimbs during circular and straight-line exercise at various gaits on a clay and sand arena surface. Statistical analysis was performed in SAS 9.4 with fixed effects of exercise type, recording, leg, and breed (PROC GLIMMIX, p < 0.05 significa...
Thompson K, Clarkson L.The extension of research into public practice is enhanced by communication and behaviour change strategies that are consistent with consumer needs and perspectives. To gain support for equine research (or to appreciate the perspectives contributing to disagreement), it is necessary to determine how aware consumers are of research, what research means to them, how they perceive its benefits (if at all) and how they engage with (or resist) it. Because of a surprising dearth of research evaluating consumer perceptions of research in any sector, our aim was to identify the perceived outputs and b...
Amano T, Tozaki T, Takasu M, Onogi A, Yamada F, Kawai M, Ueda J.We investigated whether regular changes of the sire in a breeding farm of Hokkaido Native Horses (HKDs) enables the DNA-level genetic variation of the produced animals to be maintained. The genotypes of 31 microsatellite markers were identified and analyzed in 207 animals produced in a breeding farm in which the sire was replaced every 3 to 5 years. The mean allele number indicating the degree of genetic variation was 5.97 and was similar to those reported previously. The mean observed heterozygosity was 0.74 and was higher than the expected heterozygosity, 0.69; F was -0.07, indicating that ...
Ginther OJ.Examples of research discoveries and first reports on mare reproduction by the O.J. Ginther team are (1) determined daily circulating concentrations of four hormones during the estrous cycle, (2) showed that mares can be induced to ovulate and superovulate by hormone treatment during both ovulatory and anovulatory seasons, (3) demonstrated that prostaglandin F2α was the luteolysin in mares, (4) described the mare's elaborate hormonal and biochemical mechanism for selecting the ovulatory follicle from a pool of like follicles, (5) developed the method for diagnosing fetal sex by Day 60 using l...
Clayton HM, Belock B, Lavagnino M, Kaiser LJ.The objectives of this study were to measure forces and pressure profiles when riding with a conventional saddle compared to bareback riding. An electronic pressure mat was used to compare contact area, mean total force and pressure variables for one rider riding seven horses at sitting trot with a conventional saddle or bareback. The use of a saddle was associated with a larger contact area and higher mean total force compared with the bareback condition. Mass normalized mean total force for bareback riding was lower than expected based on the rider's body mass, suggesting that shear forces e...
Waelchli RO, Winder NC.Endometrial sections from mares with varying degrees of mononuclear cell infiltration were examined for immunoglobulin (Ig)A-, IgM-, IgG(T)- and IgG(Fc)-containing cells, luminal and glandular epithelial cell Ig-staining and free interstitial Ig-staining, using a peroxidase anti-peroxidase technique. Mares with mild to moderate (Group 2) and mares with severe diffuse mononuclear cell infiltration, superimposed by acute endometritis (Group 3), had significantly higher numbers of Ig-containing cells than genitally-normal mares (Group 1). The differences between Groups 1 and 3 were significant fo...
