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Topic:Animal Studies
Animal studies involving horses encompass a range of research focused on understanding equine biology, behavior, and health. These studies often investigate various aspects of horse physiology, genetics, nutrition, and disease pathology. Researchers utilize animal studies to explore the effects of different treatments, management practices, and environmental factors on horse welfare and performance. The findings from such studies contribute to the development of improved care strategies and health interventions. This page gathers peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of animal studies conducted on horses, providing insights into their application in advancing equine science.
T2* and quantitative susceptibility mapping in an equine model of post-traumatic osteoarthritis: assessment of mechanical and structural properties of articular cartilage. To investigate the potential of quantitative susceptibility mapping (QSM) and T2* relaxation time mapping to determine mechanical and structural properties of articular cartilage via univariate and multivariate analysis. Samples were obtained from a cartilage repair study, in which surgically induced full-thickness chondral defects in the stifle joints of seven Shetland ponies caused post-traumatic osteoarthritis (14 samples). Control samples were collected from non-operated joints of three animals (6 samples). Magnetic resonance imaging (MRI) was performed at 9.4 T, using a 3-D multi-echo gr...
Behavioral and Physiological Differences between Working Horses and Chilean Rodeo Horses in a Handling Test. Non-invasive measures are preferred when assessing animal welfare. Differences in behavioral and physiological responses toward a stressor could be the result of the selection of horses for specific uses. Behavioral and physiological responses of working and Chilean rodeo horses subjected to a handling test were assessed. Five behaviors, number of attempts, and the time to cross a bridge were video recorded and analyzed with the Observer XT software. Heart rate (HR) and heart rate variability (HRV), to assess the physiological response to the novel stimulus, were registered with a Polar Equine...
In vitro evaluation of the knot-holding capacity and security, weight, and volume of forwarder knots tied with size-3 polyglactin 910 suture exposed to air, balanced electrolyte solution, or equine abdominal fat. To evaluate the effect of exposure to a balanced electrolyte solution (BES), or equine abdominal fat on the knot-holding capacity (KHC), relative knot security (RKS), weight, and volume of forwarder knots versus surgeon's knots. Methods: 315 knots tied and tested in vitro. Methods: United States Pharmacopeia size-3 polyglactin 910 suture exposed to air (dry [control]), equine abdominal fat (fat-exposed), or BES (BES-exposed) was used to tie forwarder knots with 2, 3, and 4 throws and surgeon's knots with 5, 6, 7, and 8 throws. A universal materials testing machine was used to test the tensile ...
Genome-Wide Homozygosity Patterns and Evidence for Selection in a Set of European and Near Eastern Horse Breeds. Intensive artificial and natural selection have shaped substantial variation among European horse breeds. Whereas most equine selection signature studies employ divergent genetic population structures in order to derive specific inter-breed targets of selection, we screened a total of 1476 horses originating from 12 breeds for the loss of genetic diversity by runs of homozygosity (ROH) utilizing a 670,000 single nucleotide polymorphism (SNP) genotyping array. Overlapping homozygous regions (ROH islands) indicating signatures of selection were identified by breed and similarities/dissimilaritie...
Effect of delayed plasma centrifugation on equine adrenocorticotropic hormone concentration. Plasma adrenocorticotropic hormone (ACTH) concentration is used in the diagnosis of pituitary pars intermedia dysfunction (PPID) in horses. We enrolled 10 horses, 5 PPID-positive and 5 PPID-negative, in our study, September 20-22, 2016. On day 0, 5 mL of whole blood was collected into each of 6 EDTA tubes and immediately placed in a refrigerator at 7°C. One tube was centrifuged within 15 min of collection, followed by centrifugation of one tube from each horse at 4, 8, 12, 24, and 36 h following collection. At each time, centrifuged plasma was pipetted into 1.5-mL polypropylene tubes and stor...
Animal behaviour in a human world: A crowdsourcing study on horses that open door and gate mechanisms. Anecdotal reports of horses opening fastened doors and gates are an intriguing way of exploring the possible scope of horses' problem-solving capacities. The species' natural environment has no analogues of the mechanisms involved. Scientific studies on the topic are missing, because the rate of occurrence is too low for exploration under controlled conditions. Therefore, we compiled from lay persons case reports of horses opening closed doors and gates. Additionally, we collected video documentations at the internet platform YouTube, taking care to select raw data footage of unedited, clearly...
The Genomic Makeup of Nine Horse Populations Sampled in the Netherlands. The spectrum of modern horse populations encompasses populations with a long history of development in isolation and relatively recently formed types. To increase our understanding of the evolutionary history and provide information on how to optimally conserve or improve these populations with varying development and background for the future, we analyzed genotype data of 184 horses from 9 Dutch or common horse populations in the Netherlands: The Belgian draft horse, Friesian horse, Shetland pony, Icelandic horse, Gelder horse, Groninger horse, harness horse, KWPN sport horse and the Lipizzan...
In Vitro Culture of Embryos from Horses. Establishment of optimal methods for equine embryo culture has been slow when compared to some domestic species. In part, this delay was caused by the failure of standard in vitro fertilization techniques in horses. However, the development of intracytoplasmic sperm injection (ICSI) for the assisted fertilization of equine oocytes has resulted in a renewed interest in establishing optimal methods for embryo culture. Currently, ICSI-produced equine embryos are cultured using media designed for other species or other cell cultures and, typically, with the addition of serum. Although systems spec...
Can Attractive Sticky Traps Be Used to Protect Horses From the Bites of Stomoxys calcitrans (L.) (Diptera: Muscidae). The stable fly, Stomoxys calcitrans (L.), is a bloodsucking ectoparasite that causes irritation and distress to livestock, wildlife, and humans. Both sexes are vicious blood-feeders that feed on a variety of animals. Optically attractive sticky traps have been used to capture stable flies, and some companies claim that sticky traps can protect animals from the bites of stable flies. To further investigate the protective ability of sticky traps, Home and Garden Mosquito (HGM) traps were selected for evaluations at the University of Florida Horse Teaching Unit (HTU). Broodmares coated with fluor...
Chewing patterns in horses during the intake of variable quantities of two pelleted compound feeds differing in their physical characteristics only. Pelleted feeds (PF) are popular in horse nutrition because of high palatability and improved feeding hygiene, but ingestion is faster for PF than for cereals or muesli feed. The aim of the study was to evaluate whether variable amounts of two PFs produced with different physical properties from the same batch of feed can affect feed intake patterns in horses. Chewing patterns were measured in six warmblood mares (519 ± 36.3 kg) on two PFs (small-sized PF1: ø 5 mm, length 21.9 ± 4.97 mm, large-sized PF2: edge length 15.6 ± 0.14 × 15.6 ± 0.08 mm, length 54.4 ...
Satellite DNA at the Centromere is Dispensable for Segregation Fidelity. The typical vertebrate centromeres contain long stretches of highly repeated DNA sequences (satellite DNA). We previously demonstrated that the karyotypes of the species belonging to the genus are characterized by the presence of satellite-free and satellite-based centromeres and represent a unique biological model for the study of centromere organization and behavior. Using horse primary fibroblasts cultured in vitro, we compared the segregation fidelity of chromosome 11, whose centromere is satellite-free, with that of chromosome 13, which has similar size and a centromere containing long s...
Heritability estimates of the position and number of facial hair whorls in Thoroughbred horses. According to oral traditions of horse caretakers and trainers, the differences in the position and number of facial hair whorls may be associated with temperamental traits. Elucidating genetic background of facial hair whorls and its relationship to temperamental traits may promote more efficient breeding and maintenance of racehorses. In this study, we estimated heritabilities of the position and number of facial hair whorls in Japanese Thoroughbred horses. Results: The number of facial hair whorls varied from one to four and heritability estimate in 4024 Thoroughbred horses was low (h2= 0....
Accelerometer activity tracking in horses and the effect of pasture management on time budget. Accelerometry is an accepted means of quantifying human physical activity. Quantitative physical activity tracking could be beneficial for studies into equine health and disease prevention, for example in relation to obesity management. Objective: Validate accelerometer use in grazing horses, determine between-day repeatability, and assess the effects of pasture size on time budget (i.e. duration in each activity category). Methods: Proof of concept. Methods: Accelerometers (ActiGraph) were positioned at the poll. Horses underwent 5 min of observed activity in three categories: standing, graz...
A Primitive Trait in Two Breeds of Equus Caballus Revealed by Comparative Anatomy of the Distal Limb. The 55-million-year history of equine phylogeny has been well-documented from the skeletal record; however, this is less true for the soft tissue structures that are now vestigial in modern horse. A recent study reported that two ligamentous structures resembling functional interosseous muscle II and IV were evident in Dutch Konik horses. The current study investigates this finding and compares it to members of the genus Equus to identify either a breed anomaly or functional primitive trait. Distal limbs (n = 574) were dissected from four species of Equus; E. caballus, E. asinus, E. przewalski...
Evaluation of automated erythrocyte methodology in new world camelids using the ADVIA 2120 hematology analyzer. Accurate erythrocyte measurements with ADVIA hematology analyzers require isovolumetric cell sphering in one reaction and hemolysis in another. However, camelid erythrocytes are resistant to sphering and osmotic lysis, and no published evaluation of ADVIA methods for camelids exists. Objective: The objectives were to demonstrate whether camelid erythrocytes sphere in the ADVIA red blood cell/platelet (RBC/PLT) reagent and lyse in the ADVIA cyanide HGB reagent, and to determine optimal ADVIA settings for camelids. Methods: Camelid and canine blood were diluted to 1:625 in RBC/PLT reagent and ev...
Evaluation of Two Handheld Point-of-Care Blood Gas Analyzers in Healthy Donkeys. There has been increasing interest in blood gas analysis in donkeys. "Point-of-care (POC) testing" is a diagnostic testing performed on or immediately next to the patient. This study assesses the agreement between two POC blood gas analyzers in donkeys. Arterial and venous blood samples were collected from 17 donkeys and analyzed using a fully automated blood gas analyzer (ABL 700 Series Radiometer, Denmark) (RAD) and two POC blood gas analyzers (i-STAT System; VetStat, Idexx). The parameters revealed by all three devices were submitted to a canonical discriminant analysis, to evaluate which p...
Effects of 1-MHz Ultrasound on Epaxial Muscle Temperature in Horses. The purpose of this study was to examine the tissue temperature changes that occur at various depths during 1.0-MHz ultrasound (US) treatments of the epaxial muscles in horses. Ten healthy adult mares with no lameness or orthopedic disease weighing between 465 and 576 kg were studied. Two 1.0 MHz US treatments, one at an intensity of 1.0 W/cm and one at 2.0 W/cm, were administered to the epaxial region. Needle thermistors were inserted in the epaxial muscles below the skin surface at depths of 1.0, 3.0, and 5.0 cm, directly under the US treatment area. Depths were verified with diagnostic u...
Comparison of the glucose and insulin responses of horses to 2 formulations of corn syrup. 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 ...
Sensor analysis and initial assessment of detectable first hoof contacts and last break-overs as unique signal fluctuations for equine gait analysis. The objective of the control study was to assess 2 prominent fluctuations in a single optical signal as being either a true first hoof contact or a last break-over based on descriptive measures. The study builds on initial findings from a preliminary investigation of the embedded-optical-base system's (EOBS) capabilities in signal capturing and feasibility as potential alternative to existing gait technologies, such as piezoelectric (e.g., load cell) systems. Hoof contacts and break-overs were measured (0 to 1 au; arbitrary units) using a 2.4-m (length) × 0.9-m (width) platform containing 1 E...
Grazing high and low: Can we detect horse altitudinal mobility using high-resolution isotope (δ13 C and δ15 N values) time series in tail hair? A case study in the Mongolian Altai. Carbon and nitrogen stable isotope time series performed in continuously growing tissues (hair, tooth enamel) are commonly used to reconstruct the dietary history of modern and ancient animals. Predicting the effects of altitudinal mobility on animal δ C and δ N values remains difficult as several variables such as temperature, water availability or soil type can contribute to the isotope composition. Modern references adapted to the region of interest are therefore essential. Methods: Between June 2015 and July 2018, six free-ranging domestic horses living in the Mongolian Altaï were fitte...
Elevated Sensitivity to Tactile Stimuli in Stereotypic Horses. Although stereotypic behaviors are a common problem in captive animals, why certain individuals are more prone to develop them remains elusive. In horses, individuals show considerable differences in how they perceive and react to external events, suggesting that this may partially account for the emergence of stereotypies in this species. In this study, we focused on crib-biting, the most common stereotypy displayed by horses. We compared how established crib-biters ("CB" = 19) and normal controls ("C" = 18) differed in response to a standard "personality" assessment test battery, i.e., react...
Administration of enrofloxacin during late pregnancy failed to induce lesions in the resulting newborn foals. A recent study demonstrated that enrofloxacin and ciprofloxacin cross the equine placenta without causing gross cartilage or tendon lesions in the 9-month fetus; however, long-term effects of in utero fluoroquinolone exposure remain unknown. Objective: To assess effects of fetal exposure to enrofloxacin on the resulting foal's cartilage and tendon strength. Methods: Healthy mares at 280 days' gestation were allocated into four groups: untreated (n = 5), therapeutic treatment (7.5 mg/kg enrofloxacin, PO × 14 days, n = 6), supratherapeutic treatment (15 mg/kg, PO × 14 days, n = ...
Effects of high doses of levothyroxine sodium on serum concentrations of triiodothyronine and thyroxine in horses. To investigate the effect of high doses of orally administered levothyroxine sodium (LT) on serum concentrations of triiodothyronine (T) and thyroxine (T) in euthyroid horses. Methods: 12 healthy adult horses. Methods: 10 horses initially received water (vehicle) or 240 mg (5X treatment) or 480 mg (10× treatment) of LT, and blood samples were collected at baseline (0 hours) and 0.5, 1, 2, 4, 6, 8, 10, 12, 18, 24, 48, 72, 96, and 120 hours after treatment to measure serum T and T concentrations. Three horses then received 480 mg of LT for 14 days, and T concentration was measured on days 0, 14...
The Frequency of Errors in Determining Age Based on Selected Features of the Incisors of Icelandic Horses. The structure and changes occurring to horses' teeth during ontogeny are not only used to assess the degree of somatic maturity but also the development of universal patterns and is therefore used to determine the age of horses. Research shows that methods of assessing the age of horses based on the appearance of teeth tend to suffer from relatively large errors. This is probably influenced by the results of intensive selection and being kept in living conditions that differ substantially from their natural environment. This study aimed to assess the suitability of selected features of the inc...
The Evolution of a Single Toe in Horses: Causes, Consequences, and the Way Forward. Horses are a classic example of macroevolution in three major traits-large body size, tall-crowned teeth (hypsodonty), and a single toe (monodactyly)-but how and why monodactyly evolved is still poorly understood. Existing hypotheses usually connect digit reduction in horses to the spread and eventual dominance of open-habitat grasslands, which took over from forests during the Cenozoic; digit reduction has been argued to be an adaptation for speed, locomotor economy, stability, and/or increased body size. In this review, we assess the evidence for these (not necessarily mutually exclusive) hy...
Feral horses’ (Equus ferus caballus) behavior toward dying and dead conspecifics. In the rapidly expanding field of comparative thanatology, reports from a wide range of taxa suggest that some aspects of a concept of death may be shared by many non-human species. In horses, there are only a few anecdotal reports on behaviors toward dead conspecifics, mostly concerning domestic individuals. Here, we describe the case of a 2-month-old, free-ranging male foal that died around 12 h after being found severely injured due to a presumed wolf attack, focusing on other individuals' reactions to the dying foal. We also placed camera traps near horse carcasses to investigate reaction...
Genomic measures of inbreeding in the Norwegian-Swedish Coldblooded Trotter and their associations with known QTL for reproduction and health traits. Since the 1950s, the Norwegian-Swedish Coldblooded trotter (NSCT) has been intensively selected for harness racing performance. As a result, the racing performance of the NSCT has improved remarkably; however, this improved racing performance has also been accompanied by a gradual increase in inbreeding level. Inbreeding in NSCT has historically been monitored by using traditional methods that are based on pedigree analysis, but with recent advancements in genomics, the NSCT industry has shown interest in adopting molecular approaches for the selection and maintenance of this breed. Consequent...
The Effect of Goldfish (Carassius auratus) on Water Quality in Horse Stock Tanks. Goldfish (Carassius auratus) have been reported as a method to keep water tanks clean; however, little information exists on this approach. The objectives were to evaluate the efficacy of goldfish on maintaining water quality in tanks and to evaluate the frequency that this method is used. The first objective was completed during June through October 2017 in St. Paul, MN, using plastic and metal 379 L stock tanks, each with and without goldfish in a drylot that housed six adult horses. The stocking rate was 5 goldfish per tank. Daily readings of total dissolved solids (TDS) and water turbidit...
Intra-articular triamcinolone acetonide improves lung function in horses with severe asthma. Locally administered corticosteroids are commonly used to treat joint diseases in sport and racehorses. As they are also the most potent drugs for the treatment of equine asthma, we hypothesised that the intra-articular corticosteroids used to treat joint diseases also improve the lung function in horses with severe asthma, thus potentially delaying the diagnosis of this common lung condition. Objective: To compare the effects of intra-articular (IA) and intramuscular (IM) triamcinolone acetonide (TA) on lung function in horses with severe asthma. Methods: Randomised and controlled experiment ...
Horse Paleogenomes and Human-Animal Interactions in Prehistory. A new analysis of paleogenomic data from 278 ancient horses (Fages et al. Cellhttp://doi.org/10.1016/j.cell.2019.03.049) finds that this animal - crucially important to many ancient and contemporary human societies for subsistence, transportation, conflict, and more - was domesticated in at least two different regions, but with the geographic and cultural origins of the modern domestic horse lineage remaining unknown. By tracing ancient horse population movements and inferring the spatiotemporal trajectories of phenotypic adaptations, this study provides fresh perspectives on past human group ...
