Heavy Horses Research Articles

Multicenter study investigating long-term survival after synovial lavage of contaminated and septic synovial structures in horses presented to 10 UK referral hospitals.

To report the long-term survival of adult horses that were subjected to synovial lavage for treatment of contaminated and septic synovial structures. Multicenter, prospective observational trial. Horses (n = 240) presented for synovial sepsis at 10 UK referral centers. Data for horses presented for treatment of synovial sepsis were collected over a 15 month recruitment period. Owners were contacted a minimum of 365 days after surgery using a structured client interview to assess long term survival. Descriptive statistics, and univariable and Cox proportional hazards models for postoperative survival time were developed. Survival to discharge was 228/240 (95%) and overall long-term survival was 89.4% (185/207). Unknown cause of injury (p = .017), increasing duration of surgery (p = .003), increasing weight (p = .008), forelimb injuries (p = .027), and type of synovial structure (p = .008) were found to be associated with death using Cox proportional hazards models. This study provides information on risk factors associated with survival and death after treatment for synovial sepsis at referral hospitals in the UK. Survival to discharge and long-term survival was excellent. Heavier horses, injuries affecting the forelimbs, tendon sheaths and bursae were associated with poorer long term outcomes. Longer duration of surgery was also found to be associated with a worse prognosis. These findings help to provide prognostic information for owners and veterinarians treating horses with synovial sepsis.

Molecular and Serological Detection of Vector-Borne Pathogens Responsible for Equine Piroplasmosis in Europe between 2008 and 2021.

Equine piroplasmosis (EP) is caused by Theileria (T.) equi and/or Babesia (B.) caballi. The aim was to assess the percentage of positive test results for EP in horses in Europe and to identify risk factors for pathogen contact/infection. This study included results from PCR and competitive enzyme-linked immunosorbent assay testing requested by European veterinarians between 2008 and 2021. Binary bivariate logistic regression was used to analyze risk factors. A total of 4060 horses were included. PCR testing was positive in 9.7% (154/1589), serology for T. equi in 15.2% (393/2591) and for B. caballi in 6.8% (175/2578). The odds of positive serology increased by 6.8% (B. caballi, p = 0.008) and 9.5% (T. equi, p < 0.001) each year. Regionality had a statistically significant impact on PCR (Eastern p = 0.047/OR = 1.605; Southern p = 0.029/OR = 1.451; Central p = 0.007/OR = 0.617) and serological testing for T. equi (Southern p < 0.001/OR = 2.521; Central p < 0.001/OR = 0.537; Northern p = 0.003/OR = 0.462), as well as breeds on seroprevalence of B. caballi (heavy horses: p = 0.016/OR = 2.239) and T. equi (ponies: p = 0.007/OR = 0.340; warmbloods: p = 0.025/OR = 1.602). In conclusion, there was a significant geographical impact on the results of PCR and serology, consistent with known vector habitats. The rising numbers of horses tested serologically positive highlights the importance of surveillance.

Validation of a novel clinical tool for monitoring distal limb stiffness.

To validate a novel technique to measure limb stiffness in a clinical setting. Three horses and three ponies owned by the Royal Veterinary College. Limb stiffness indices for both forelimbs were first derived using the gold standard of kinematic analysis. Using the same animals, limb stiffness indices were then calculated using portable floor scales to record weight and an electrogoniometer to record changes in metacarpophalangeal joint angle. The two techniques were then assessed for correlation and repeatability. The repeatability of limb stiffness measurement using the novel clinical tool was considered to be good based on a small coefficient of variation (5.70%). The correlation of limb stiffness as derived by both methods was high (r = 0.78, p < 0.01). Limb stiffness was positively correlated with the mass of the subject (r = 0.85, p < 0.01), with heavier horses having greater limb stiffness. This study has compared a novel method to measure distal forelimb stiffness non-invasively in a clinical setting to kinematic analysis in six equids. It has demonstrated that limb stiffness increases in a linear fashion with body mass consistent with the role of forelimbs providing energy storage. Because in vivo limb stiffness has been shown previously to alter with injury to the superficial digital flexor tendon, it is hypothesized that this technique will offer a practical technique for the clinician to assess limb stiffness in clinical cases. Further study will be necessary to determine its clinical usefulness in such cases.

The genetic basis of the sperm quality of stallions

One of the important factors affecting the reproductive function is the genotype of the animal. The method of genomic selection is based on the use of polymorphic single nucleotide substitutions (SNP) as markers for determining the value of the genotype of an animal or plant. The formation and functioning of the reproductive system of animals occurs as a result of the coordinated interaction of a wide range of genes. The search for genomic associations of GWAS (Genome-Wide Association Studies) with signs of fertility will allow further selection of animals based on these indicators at the genomic level. Sperm was obtained with the help of mares in hunting and on a phantom using an artificial Hannover vagina (Minitube, Germany). The sperm of each stallion was collected at least three times. The semen quality of 96 stallions of different breeds (Arabian, Akhal-Teke, Trakenen, thoroughbred horse, Oryol trotter, French trotter, Soviet heavy horse, Shetland pony, Welsh pony, horses of different breeds) was analyzed. High variability of sperm quality indicators was revealed. For example, the concentration of sperm in the ejaculate varied from 59 to 514 million /ml, progressive mobility from 20 to 87%, and the number of cells without damage from 21.6 to 95.6%. Such variability of the studied features makes it possible to assume that their formation in the process of ontogenesis occurs under the influence of genetic factors. The GWAS analysis of ejaculate volume, concentration and motility of stallion sperm revealed potential candidate genes associated with these indicators. The associations identified in our study are promising candidates for further identification of the biological mechanisms underlying the quality of stallion sperm.

Wolf contact in horses at permanent pasture in Germany.

Wolves returned to Germany in 2000, leading to fear in German horse owners that their horses could be in danger of wolf attacks or panic-like escapes from pastures when sighting wolves. However, reports from southern European countries indicate that wolf predation on horses diminishes with increasing presence of wildlife. Therefore, we conducted a long-term, filed observation between January 2015 and July 2022 on 13 non breeding riding horses, mares and geldings, kept permanently on two pastures within the range of wildlife and a stable wolf pack with annual offspring. Wildlife cameras at the fences of the pastures made 984 times recordings of wolves and 3151 times recordings of wildlife in and around the pastures. Between 1 January 2022 and 23 March 2022 we observed two stable horse groups. Pasture 1 was grazed by five horses of mixed breed, four mares and one gelding, with the median age of 8 years (min. = 6y, max. = 29y). Pasture 2 was grazed by eight heavy warmbloods and draught horses, three mares and five geldings, with the median age of 16 years (min. = 13y, max. = 22y). During this period no wolf was recorded at pasture 2, but wild boar several times, whereas at pasture 1, wolves were recorded 89 times, and for the wildlife mostly hare. Wolves may have avoided pasture 2 because of the presence of wild boar or because the large group of older, heavy breed horses may have formed a stable, protective group. The latter needs to be confirmed in a follow-up field observation, which records anti-predator behavior and welfare indicators in horses. In conclusion, wolves did not attack the mature horses on pastures with plenty of wildlife and the horses did not respond to the presence of wolves with visible signs of reduced welfare or panic. This indicates that wolves may prefer to prey on easily accessible wildlife around and at horse pastures and that Central European horses become accustom to the presence of non-hunting wolves.

The Genetic Diversity of Stallions of Different Breeds in Russia.

The specifics of breeding and selection significantly affect genetic diversity and variability within a breed. We present the data obtained from the genetic analysis of 21 thoroughbred and warmblood horse breeds. The most detailed information is described from the following breeds: Arabian, Trakehner, French Trotter, Standardbred, and Soviet Heavy Horse. The analysis of 509,617 SNP variants in 87 stallions from 21 populations made it possible to estimate the genetic diversity at the genome-wide level and distinguish the studied horse breeds from each other. In this study, we searched for heterozygous and homozygous ROH regions, evaluated inbreeding using FROH analysis, and generated a population structure using Admixture 1.3 software. Our findings indicate that the Arabian breed is an ancestor of many horse breeds. The study of the full-genome architectonics of breeds is of great practical importance for preserving the genetic characteristics of breeds and managing breeding. Studies were carried out to determine homozygous regions in individual breeds and search for candidate genes in these regions. Fifty-six candidate genes for the influence of selection pressure were identified. Our research reveals genetic diversity consistent with breeding directions and the breeds' history of origin.

Ultrasonography-based diagnosis of hemorrhage syndrome in adipose tissues in the crest of the neck of heavy horse breeds.

Hemorrhage syndrome in adipose tissues in the crest of the neck (HSCN), specifically in hemorrhagic adipose tissues on the longitudinally sectioned surface of the neck fat at the dorsal nuchal ligament, is prevalent in heavy horse breeds. Herein, we aimed to establish an ultrasonographic method to successfully diagnose HSCN in heavy horse breeds and assess its efficacy. Horses with homogeneous echogenicity images were included in the control group, whereas those with linear high-echogenicity images were classified as having HSCN. Horses with confirmed linear high-echogenicity images exhibited pathological features and significantly higher percentages of adipose tissue with hemorrhage than those observed in horses with homogeneous echogenicity images (P<0.01). Our results suggest the effectiveness of ultrasonography in identifying and diagnosing HSCN.

PLNGene Analysis in Horses: Multiway Approach for the Investigation and Validation of Molecular Variation

In this study, a molecular characterisation of the PLN gene with whole genome sequencing (WGS) and complete transcriptome sequencing data was performed on 868 horses, supported by Sanger sequencing and the PCR-RFLP method. The PLN gene encodes phospholamban – an integral membrane protein – and while phosphorylated inhibits the SR Ca2+-ATPase (SERCA) transport of Ca2+ into reticulum in the cardiac and skeletal muscles. According to the current knowledge, we hypothesised that the presence of Single Nucleotide Polymorphisms (SNPs) in the PLN gene sequence may be related to an individual's lifestyle and would remain under selection pressure. The obtained results indicated the occurrence of 14 polymorphisms of which 7 were upstream, and 7 downstream PLN gene variants according to the EquCan3.0 reference. The mRNA sequencing confirmed the presence of 3' and 5' UTR regions belonging to the PLN transcript that was in accordance with EquCab2.0, and was missed in the current version. The comparison of two reference genomes and the validation of the NGS data allowed for the 3'UTR variant (rs1146603334) to be detected, showing differences in the genotype and allele distributions across five horse breeds. A similar genotype frequency in warmblood breeds of horses (Arabians and Thoroughbreds), compared to native and heavy horses (Polish Konik, Draft and Hucul horses), indicated that this locus was under selection pressure.

Epidemiological survey, general blood biochemistry, and histological examination of slaughtered heavy horse breeds with hemorrhage in the adipose tissue in the crest of the neck.

Fifty-four slaughtered horses were classified into groups having adipose tissue in the crest of the neck with or without hemorrhage (AH and NH groups, respectively). Blood biochemical tests (Alb, TP, T-bil, GOT, GPT, LDH, T-cho, and BUN) and an epidemiological survey (age, gender, weight, origin, breed, BCS, CNS, and hoof disease) were performed. T-bil tended to be high, while the other parameters were normal. Weight, BCS, and CNS were higher in the AH group (P<0.05). GOT was lower in the AH group (P<0.05). It was suspected that the horses in the AH group had lipomatosis. It was assumed that the adipose tissue of the horses in the AH group contained damaged capillaries, and inflammation was confirmed based on evidence of macrophages and lymphocytes.

Diagnosis of Hemorrhage Syndrome in the Cresty Neck Adipose Tissues in Heavy Horse Breeds Using Ultrasonography

Diagnosis of Hemorrhage Syndrome in the Cresty Neck Adipose Tissues in Heavy Horse Breeds Using Ultrasonography

Age-Related Changes in the Behaviour of Domestic Horses as Reported by Owners.

Simple SummarySome treatments for common problem behaviours in domestic horses can compromise horse welfare. Such behaviours can be the manifestation of pain, confusion and conflict. In contrast, among the desirable attributes in horses, boldness and independence are two important behavioural traits that affect the fearfulness, assertiveness and sociability of horses when interacting with their environment, objects, conspecifics and humans. Shy and socially dependent horses are generally more difficult to manage and train than their bold and independent counterparts. Previous studies have shown how certain basic temperament traits predict the behavioural output of horses, but few have investigated how the age of the horse and the age it was when started being trained under saddle affect behaviour. Using 1940 responses to the Equine Behaviour Assessment and Research Questionnaire (E-BARQ), the current study explored the behavioural evidence of boldness and independence in horses and how these related to the age of the horse. Results revealed age-related effects on boldness and independence of horses. Older horses were bolder than younger horses, but horses started under saddle at an older age were less bold and independent than those started at a younger age. Additionally, significant differences in boldness and independence relating to specific breeds and primary equestrian disciplines also emerged. Finally, riders with eight or more years of riding experience reported having more independent horses than those who had ridden their whole lives. Understanding how horses’ ages affect behavioural traits can improve horse–rider matching and potentially also optimise welfare.The broad traits of boldness and independence in domestic horses can affect their usefulness and, indirectly, their welfare. The objective of the current study was to explore associations between attributes that reflect equine boldness and independence with both the age of horses and the age at which they were started under saddle, as well as other variables including breed, colour and primary equestrian discipline. All data were sourced from responses (n = 1940) to the 97-question online Equine Behaviour Assessment and Research Questionnaire (E-BARQ). Twenty E-BARQ items from the dataset were selected to reflect boldness and independence and were tested for univariate significance at p < 0.2. Multivariable modelling of the effect of age on remaining traits was assessed by an ordinal logistic regression, using a cumulative log odds model. This revealed that older horses were bolder (p = 0.012). However, horses started under saddle at an older age were less bold and less independent (p = 0.040 and p = 0.010, respectively). Australian Stock Horses were bolder and more independent (p = 0.014 and p = 0.007, respectively) than crossbreed horses. Horses used for breeding conformation (p = 0.039), working equitation (p = 0.045), eventing (p = 0.044) and traditional working horses (p = 0.034) were bolder than those used for other disciplines. Dressage (p = 0.039) and therapy (p = 0.040) horses were less bold than horses used for other disciplines. Stallions were bolder (p = −0.034) than geldings. Brown (p = 0.049) and chestnut (p = 0.027) horses were less bold than bay horses. Compared to crossbreed horses, Thoroughbreds (p = 0.000) and companion horses (p = 0.017) were less bold whilst heavy horses (p = 0.029) and ponies (p = 0.044) were bolder. Compared to pleasure horses, mounted games horses (p = 0.033) were less independent whereas working equitation horses (p = 0.020) were more independent. Riders with more than eight years’ experience reported more independence in their horses (p = 0.015) than those who had ridden their whole lives. The study findings suggest that boldness and independence are separate traits and only boldness was associated with the age of the horse. Factors that relate to desirable boldness and independence are important in ridden horses because they can affect rider safety. Results from this study should improve horse–rider matching and thereby potentially enhance horse welfare.

Genetic Variability in the Italian Heavy Draught Horse from Pedigree Data and Genomic Information.

This study aimed to investigate the genetic diversity in the Italian Heavy Horse Breed from pedigree and genomic data. Pedigree information for 64,917 individuals were used to assess inbreeding level, effective population size (Ne), and effective numbers of founders and ancestors (fa/fe). Genotypic information from SNP markers were available for 267 individuals of both sexes, and it allowed estimating genomic inbreeding in two methods (observed versus expected homozygosity and from ROH) to study the breed genomic structure and possible selection signatures. Pedigree and genomic inbreeding were greatly correlated (0.65 on average). The inbreeding trend increased over time, apart from periods in which the base population enlarged, when Ne increased also. Recent bottlenecks did not occur in the genome, as fa/fe have shown. The observed homozygosity results were on average lower than expected, which was probably due to the use of French Breton stallions to support the breed genetic variability. High homozygous regions suggested that inbreeding increased in different periods. Two subpopulations were distinguished, which was probably due to the different inclusion of French animals by breeders. Few selection signatures were found at the population level, with possible associations to disease resistance. The almost low inbreeding rate suggested that despite the small breed size, conservation actions are not yet required.

Mitochondrial DNA variation in the Italian Heavy Draught Horse.

BackgroundIn the last decades, Italy as well as other developed countries have registered a decrease in the population size of many local horse breeds. The continuous crossbreeding has determined the dilution of genetic heritage of several native breeds. The Italian Heavy Draught Horse (IHD) is the only autochthonous Italian coldblooded horse among these breeds; therefore, it represents a resource to be preserved. In 1927, the first generation of this breed was officially created by crossing different Heavy Draught horses with local mares and recorded in a Studbook.MethodologyTo provide the first comprehensive overview of the genetic diversity of Italian Heavy Draught horses from Central Italy, we produced and phylogenetically analysed 52 mitochondrial DNA (mtDNA) control-region sequences. Furthermore, we evaluated data available from GenBank (N = 568) to have a more complete scenario and to understand the relationships with other European Heavy Draught horse breeds.ResultsAmong the IHD samples that were analysed, we identified ten of the 17 haplogroups described in modern horses. Most of these sequences fell into L, G, and M lineages, thus showing the overall mtDNA legacy of the ancestral mares that were probably used at the initial stages of breeding selections a long time ago. The high mitochondrial haplotype diversity (Hd = 0.969) found in our samples reflected the multiple maternal origins of the horses. Our results highlighted a considerable percentage of haplotypes shared especially with Bardigiano and Hungarian Heavy Draught breeds. Furthermore, both the presence of four unique haplotypes detected in our samples and their absence among all equine mitochondrial published data demonstrate a mitochondrial peculiarity that needs to be further investigated and preserved with careful breeding practices.

Prevalence of Electrolyte Disturbances and Perianesthetic Death Risk Factors in 120 Horses Undergoing Colic Surgery

The objective of this study was to determine the prevalence of intraoperative electrolyte disturbances and risk factors associated with perianesthetic death in horses undergoing colic surgery. The files of 120 horses meeting the inclusion criteria were reviewed. Data retrieved from the medical records, including demographic data and the occurrence of electrolyte disturbances and other intraoperative complications, were analyzed with a two step-approach by univariate and multivariate logistic regression models. Hypocalcemia was the most represented electrolyte disturbance (52.5%), followed by hypokalemia (30.0%) that was associated with intraoperative administration of salbutamol (P = .045). Perianesthetic death occurred in 46 horses, accounting for an overall mortality rate of 38.3%. Risk factors associated with death were anesthetic duration (P = .001), body weight (P = .020), presence of gastric reflux before anesthesia (P = .021), and intraoperative tachycardia (P = .043) and acidosis (P = .025). The mortality in the study population was comparable to previously reported findings. Based on the study findings, it is advisable to optimize hemodynamics prior to anesthesia, in order to prevent intraoperative tachycardia that is associated with increased risk of death. Heavier horses and those with gastric reflux may have a higher risk of fatalities, and intraoperative salbutamol administration may contribute to hypokalemia.

U boku króla. Chorągiew nadworna królów Polski u schyłku XV wieku

Chorągiew nadworna złożona była z dworzan, zwanych dworzanami konnymi (curienses). Będąc jednostką elitarną, stanowiła prywatny oddział władcy. Zgodnie z rejestrem spisanym w ostatnich latach XV w., po wyprawie mołdawskiej, w szeregach chorągwi odnotowano 60 dworzan konnych, stojących na czele swoich pocztów, z których większość liczyła od czterech dosześciu jeźdźców. Łącznie w rejestrze odnotowano 288 jeźdźców. W pocztach jeźdźcy w uzbrojeniu strzelczym stanowili ponad połowę, kopijnicy zaś około 13% wszystkich odnotowanych jeźdźców. W rejestrze występują konie kopijnicze i strzelcze, należy wspomnieć również o koniach rackich i tatarskich. Dworzanie wchodzący w skład chorągwi nadwornej byli szlachtą, dla wielu z nich kariera u boku króla stała się przepustką do dalszych awansów oraz udziału w życiu politycznym i kulturalnym. W omawianym rejestrze odnotowani zostali również dworzanie – pokojowcy (cubicularii), którzy służyli na dworze konno, niekiedy ze swymi pocztami. Pokojowcy, obok dworzan konnych, wchodzili najpewniej w skład orszaku królewskiego oraz chorągwi nadwornej.

Animal and environmental factors associated with gestation length in the endangered Old Kladruber horse

Little is known about factors influencing gestation length in heavier types of horses. The objective was to assess the effects of the weight and age of mares, weight and sex of foals, lactation, month and year of conception, month of foaling, stallion and mare on gestation length in the endangered Old Kladruber breed that once served as a heavy coach horse for ceremonies of the Imperial Court in Vienna. The study was performed at the stud farm Slatinany, Czech Republic and reports data from foaling seasons between 2001 and 2018. A total of 649 gestations were included in the study. Gestation in mares weighing 680 kg and more was 1.9 days shorter than in those weighing up to 639 kg (P < 0.0001). Gestation in lactating mares was 3.9 days shorter than in non-lactating mares (P < 0.0001). Gestation was longest in mares conceiving in March (343.9 ± 0.60 days); thereafter it gradually shortened, with the shortest (P < 0.0001) in mares conceiving in July (334.9 ± 0.90 days). Gestation length in mares increased (P < 0.0001) from February foaling (340.4 ± 0.73 days) to March foaling (343.6 ± 0.55 days), and then decreased (P < 0.0001) up to the end of the breeding season in June (336.7 ± 0.92 days). Year of conception had an effect on GL (P < 0.02). Gestation in mares carrying male foals was 2.0 days longer than in those carrying female foals (P < 0.01). Gestation in mares delivering foals weighing 70 kg and more was 1.0 days longer than in those delivering foals weighing up to 60 kg (P < 0.01). Mare’s age had no effect on gestation length. In conclusion, gestation length was associated with the weight of mares and foals, lactation, month and year of conception, month of foaling, and sex of foals.

Технология интенсивного выращивания племенных кобыл Литовской тяжеловозной породы в ЗАО племзаводе «Семеновский»

Технология интенсивного выращивания племенных кобыл Литовской тяжеловозной породы в ЗАО племзаводе «Семеновский»

Persian Riders in the Aethiopica of Heliodorus. A reliable source?

The description of the Persian Riders in Aethiopica of Heliodorus is often regarded a reliable source to reconstruct the tactics and armament of Iranian heavy cavalry of the Sasanian period, sometimes even spread to its Roman equivalents. The conventional nature of entire text is somehow disregarded in this particular point which is not less conventional than all other depictions of the novel. The description uses fixed phrases designed to flatter the erudite reader, not to describe actual combat troops of Achaemenid era disguised in fourth century attire. The Heliodorus’ description must be treated with utmost carefulness and can be a tertiary source for reconstruction of the Sasanian heavy horse, at best.

High intensity, short duration pulling in heavy horses: physiological effects of competition and rapid weight change

BackgroundThe Heavy Horse Pull is a competition where teams of two horses pull an increasingly heavy sled for a short distance. Similar to human wrestlers, some horses may undergo rapid weight change in order to enter a lower weight category. The objectives were to study the physiological effects of this practice as well as of the pulling competition in draft horses.ResultsFifty horses were divided into light-, middle- and heavyweight categories based on their arrival weights and competed 1–3 days after. Body weight was measured upon arrival and pre-competition. Blood was sampled for chemistry and high sensitivity cardiac troponin T (hscTnT) at arrival, pre- and post-competition in 34, 26 and 20 horses, respectively. Body weight increased significantly between arrival and pre-competition for light (7.2% (Median: 62.8Kg (41.7–77.0)) and middle (8.6% (Median: 80.5Kg (62.7–90.9)) weight categories. Change in body weight was correlated (r = 0.69, p = 0.002) with competition ranking for middleweights. The ratios of weight pulled to team body weight were 2.7 (1.9–2.8), 2.6 (2.5–2.6) and 2.4 (2.2–2.5) for the lightweights, middleweights and heavyweights, respectively. Blood chemistry indicated hemoconcentration on arrival in the middleweight and lightweight horses. Hemoconcentration was not seen on arrival in some horses with marked rapid weight change. Overall, no chemistry parameter changed between pre- and post-competition. The hscTnT stayed within normal range post-competition.ConclusionsWhile horses arrived to the event with indications of hemoconcentration, they appeared to have sufficient time to rehydrate prior to competition, and the effects of the competition were reversible within 3 h.

Measurement of intraocular pressure in healthy anesthetized horses during hoisting

ObjectiveTo measure intraocular pressure (IOP) in horses during hoisting after induction of anesthesia. Study designProspective nonrandomized clinical study. AnimalsEighteen healthy adult horses aged [mean±standard deviation (SD)] 10±4.2 years and weighing 491±110 kg anesthetized for elective procedures. MethodsIOP was measured in the superior eye of each horse based on planned recumbency after induction of anesthesia. Measurements were taken directly after premedication with xylazine or detomidine with butorphanol, after induction with diazepam–ketamine, after intubation, when suspended by the hoist and on the operating table. During hoisting, the head was supported and the eye–heart height was measured to account for variations in head positioning among patients. IOPs were compared across time points using repeated-measures analysis of variance. Regression was used to compare IOP outcome with potential cofactors. ResultsCompared with measurements after premedication (17.5±2.5 mmHg) (mean±SD), hoisting significantly increased IOP (32.4±15.3 mmHg) (p<0.01). The highest recorded IOP in the hoist was 80.0 (range, 16.0–80.0) mmHg. The difference in IOP between premedication and hoisting was 15.0±16.2 (range, –1.0 to 68.0) mmHg. Body weight had a significant effect on absolute IOP and change in IOP in the hoist (p<0.01). Conclusions and clinical relevanceHoist IOP was significantly higher than post-premedication IOP with heavier horses having higher hoist IOPs and greater increases in IOP. The clinician should take this relationship into account when anesthetizing and hoisting larger horses where an increase in IOP could be detrimental.