Topic:Cohort Study
A cohort study in equine research involves the systematic observation of a group of horses over a period of time to assess specific health outcomes. This type of study is designed to identify associations between exposures and outcomes by following horses with shared characteristics or conditions. Cohort studies can be prospective, where horses are followed into the future, or retrospective, where past records are used to trace outcomes. These studies are valuable for understanding the natural history of diseases, evaluating risk factors, and assessing the effectiveness of interventions. This page compiles peer-reviewed research studies and scholarly articles that explore the methodology, findings, and implications of cohort studies in the context of equine health and management.
Closure of the neuro-central synchondrosis and other physes in foal cervical spines. The neuro-central synchondrosis (NCS) is a physis responsible for the growth of the dorsal third of the vertebral body and neural arches. When the NCS of pigs is tethered to model scoliosis, stenosis also ensues. It is necessary to describe the NCS for future evaluation of its potential role in equine spinal cord compression and ataxia (wobbler syndrome). Objective: To describe the NCS, including when it and other physes closed in computed tomographic (CT) scans of the cervical spine of foals, due to its potential role in vertebral stenosis. Methods: Post-mortem cohort study. Methods: The cerv...
A retrospective comparison of postoperative outcomes in ovariectomised jennies (Equus asinus) treated with phenylbutazone or flunixin meglumine. Clinically, flunixin meglumine (FM) and phenylbutazone (PBZ) are preferentially selected for the treatment of visceral and musculoskeletal pain, respectively, in horses. In donkeys, there is no information to support or refute this conventional conjecture. Objective: To compare postoperative outcomes in a group of jennies treated with intravenous FM or oral PBZ. Methods: Fourteen jennies unilaterally ovariectomised by standing left flank laparotomy. Methods: Retrospective cohort study. Methods: Data from medical records of ovariectomised jennies (case details, weight, non-steroidal anti-inflam...
Prospective, longitudinal assessment of subchondral bone morphology and pathology using standing, cone-beam computed tomography in fetlock joints of 2-year-old Thoroughbred racehorses in their first year of training. Catastrophic injuries of the fetlock joints occur in Thoroughbred racehorses and are preceded by stress-induced bone injury. Early detection of subchondral bone injury is essential to prevent irreversible damage or bone failure. Objective: To investigate the use of standing, robotic cone-beam computed tomography (CBCT) for assessing longitudinal changes in subchondral bone morphology and pathology of the fetlock joints associated with race training in young Thoroughbreds. Methods: Observational cohort study. Methods: Forty-one 2-year-old Thoroughbred racehorses were recruited prior to the star...
Radiological findings in the proximal sesamoid bones of yearling and 2-year-old Thoroughbred sales horses: Prevalence, progression and associations with racing performance. Radiological findings in the proximal sesamoid bones (sesamoids) are a persistent source of controversy at Thoroughbred sales, due to inconsistent classification and conflicting assignment of potential clinical importance. Objective: To define the prevalence of sesamoid findings on sales repository radiographs in yearling and 2-year-old Thoroughbreds and to analyse associations with racing performance. To track the changes in sesamoid findings between 1 and 2 years of age in horses that present for sale at both ages. Methods: Prospective cohort study using an enrolled sample. Methods: Horses...
Effect of dexamethasone on antibody response of horses to vaccination with a combined equine influenza virus and equine herpesvirus-1 vaccine. Dexamethasone is routinely administered to horses but its effect on the antibody response to a commercial EIV/EHV vaccine is unclear. Objective: Horses receiving dexamethasone will have lower postvaccination antibody levels against EIV and EHV-1 than vaccinated controls. Methods: Fifty-five healthy adult research horses. Methods: Randomized cohort study. Control (no vaccine, group 1), vaccination only (EIV/EHV-1/EHV-4, Prestige 2, Merck Animal Health, group 2), vaccination and concurrent single intravenous dose of dexamethasone (approximately .05 mg/kg, group 3), vaccination and 3 intravenou...
Potential risk factors for fetal loss due to umbilical cord torsion in the mare. Equine pregnancy failure can occur throughout gestation with etiologies varying by region. In Europe, umbilical cord torsion (UCT) has been reported to account for up to 52% of abortions and stillbirths. Little is known about what causes excessive twisting of the umbilical cord (UC), and up till now, only the length of the UC has been identified as a risk factor for UCT. The aim of the present study was to determine the association of potential maternal and fetal risk factors with UCT and umbilical cord length (UCL). A retrospective cohort study was performed on aborted or prematurely delivere...
Outcome and racing performance following standing fracture repair in 245 horses. Repair of sagittal proximal phalanx (P1) and parasagittal metacarpal/metatarsal III (MC/MTIII) fractures has evolved over recent decades from a procedure carried out solely under general anaesthesia, to one commonly performed under standing sedation. To date, standing fracture repair has not been evaluated for large cohorts. Objective: To determine short-term (survival to discharge) and long-term (return to racing) outcomes of horses undergoing standing repair of MC/MTIII and P1 fractures, and to compare pre-surgical and post-surgical racing performance. Methods: Single-centre retrospective co...
Evaluation of seasonal influences on adrenocorticotropic hormone response to the thyrotropin-releasing hormone stimulation test and its accuracy for diagnosis of pituitary pars intermedia dysfunction. Pituitary pars intermedia dysfunction (PPID) is an age-related neurodegenerative disorder, affecting >20 % of older horses. There is a need for improved endocrine tests for early disease detection, and the thyrotropin-releasing hormone (TRH) stimulation test has been recommended for diagnosis of early or mild cases. However, it is currently not recommended for year-round use due to marked seasonal variability. The aims of this cohort study were to evaluate effects of month and season on adrenocorticotropic hormone (ACTH) responses to TRH stimulation and to derive monthly cut-offs for PPID d...
Associations between feeding and glucagon-like peptide-2 in healthy ponies. Gastrointestinal peptides, such as glucagon-like peptide-2 (GLP-2), could play a direct role in the development of equine hyperinsulinaemia. Objective: To describe the secretory pattern of endogenous GLP-2 over 24 h in healthy ponies and determine whether oral administration of a synthetic GLP-2 peptide increases blood glucose or insulin responses to feeding. Methods: A cohort study followed by a randomised, controlled, cross-over study. Methods: In the cohort study, blood samples were collected every 2 h for 24 h in seven healthy ponies and plasma [GLP-2] was measured. In the cross-over...
Factors associated with safe completion of Fédération Equestre Internationale eventing cross-country (2008-2018). Equestrian eventing involves competing in three phases: dressage, jumping, and cross-country. Competitors are ranked by number of penalties accrued-with those who have fewer penalties ranked higher. Completing the cross-country phase with zero obstacle penalties is commonly referred to as 'running clear'. Understanding factors associated with running clear can help athletes plan strategically for success, while also helping governing bodies to refine qualification criteria for elite levels. Objective: This study was carried out to identify factors associated with running clear in the cross-cou...
Plantar osteochondral fragments in young Standardbreds are associated with minimal joint inflammation at the time of surgical removal. Plantar osteochondral fragments (POF) are common but their effect on joint health of young Standardbreds in race training is largely unknown. Objective: Evaluate the inflammatory effects of POF in metatarsophalangeal joints of young Standardbreds as a step towards developing evidence-based recommendations for surgical removal. Methods: Cohort study. Methods: Forty-nine Standardbred horses (age 11-33 months) presented for surgical removal of POF from 56 metatarsophalangeal joints. Synovial tissue collected at arthroscopy was subjected to histopathology. IL-1β, TNF-α, and PGE-2 were measured ...
Epidemiology of race day injury in young professional jockeys in Great Britain from 2007 to 2018: a retrospective cohort study. There are limited injury data in professional horse racing, particularly by sex. To describe injury incidence, characteristics and falls in male and female, flat and jump jockeys in Great Britain. Retrospective cohort study of professional jockeys in Britain. 245 jockeys licensed between 2007 and 2017. The primary outcome measure was injury on a race day. Injury incidence (per 1000 rides; per 1000 falls) was derived. Incidence-rate ratios (IRR) were calculated to compare incidence between flat and jump racing, male and female jockeys, and male flat and male jump jockeys for: (i) injury inciden...
Nicoletella semolina in the airways of healthy horses and horses with severe asthma. Nicoletella semolina was identified in the airways of horses and its low prevalence could be because of its difficult differentiation from other Pasteurellaceae. Objective: To develop a molecular method for the identification of N. semolina and to evaluate its prevalence in the mouth and the airways of healthy and severe asthmatic horses. Methods: Six healthy and 6 severely asthmatic horses in phase I, 10 severely asthmatic horses in phase II, and 10 healthy horses in phase III. Methods: Cohort (phases I and II) and cross-sectional (phase III) studies. Quantitative polymerase chain reaction pr...
Case-Control Comparison of Cervical Spine Radiographs From Horses With a Clinical Diagnosis of Cervical Facet Disease With Normal Horses. The accuracy of using radiographs to diagnose cervical facet osteoarthritis (CFA) in horses is undetermined. Further investigation is required to determine the clinical significance of radiographic evidence of CFA, the prevalence of radiographic changes in horses without clinical signs, and the long-term efficacy of intra-articular CFA treatment. The objectives of this study is to compare degenerative changes of the cervical facet joints of the cervical vertebrae on radiographs of horses with clinical signs of CFA with healthy cohort-matched horses, to compare clinical findings between groups,...
Effects of coadministration of corn oil and ponazuril on serum and cerebrospinal fluid concentrations of ponazuril in horses. Ponazuril is used for the treatment of equine protozoal myeloencephalitis (EPM). Coadministration of ponazuril with oil could result in higher serum and cerebrospinal fluid (CSF) concentrations of ponazuril. Objective: Coadministration of corn oil will result in higher serum and CSF concentrations of ponazuril than when ponazuril is administered alone. Methods: Ten resident university-owned adult horses of either sex and >2 years of age. Methods: Cohort study. Ponazuril oral paste (5 mg/kg BW; ponazuril treatment group (PON); n = 5), or ponazuril oral paste (5 mg/kg BW; ponazuril and oil tre...
Age-related differences in blood pressure, ultrasound-derived arterial diameters and arterial wall stiffness parameters in horses. Arterial rupture mainly affects older horses. The reason why older horses are more prone to arterial rupture and which underlying vascular changes predispose older horses to aortic rupture is still unclear. Objective: To investigate the effect of ageing on the equine arterial wall and blood pressure. Methods: Cohort study. Methods: Non-invasive blood pressure measurement using a tail cuff and vascular ultrasound from aorta, common carotid artery and external iliac artery was performed in 50 healthy young (3-7 years) and 50 healthy old Warmblood horses (>18 years). Arterial diameters and c...
Risk factors for duration of equine rhinitis A virus respiratory disease. Infectious respiratory disease is common in young horses and can impact athletic performance and long-term health. Significant variation in the duration of clinical disease has been observed, even in the absence of secondary complications. The determination of factors associated with disease chronicity may facilitate clinical decision-making and the development of improved biosecurity protocols. Objective: To investigate contact network characteristics, and demographic variables associated with time to clinical recovery from Equine Rhinitis A virus respiratory disease. Methods: Prospective coh...
Does Exercise Alter Gut Microbial Composition? A Systematic Review. The objective of this systematic review of literature was to evaluate and summarize published research that has investigated the association between exercise and gut microbial composition in mammals. This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The databases searched for this review included: PubMed; PubMed Central; Medline; Cumulative Index of Nursing and Allied Health Literature; Web of Science; Commonwealth Agricultural Bureaux Direct; Health Source: Nursing Academic Edition; Clinicaltrials.gov; International Prosp...
Competition lifespan survival analysis in the Norwegian-Swedish Coldblooded Trotter racehorse. Studies of large racing populations have established clear differences in the career profile of stallions, mares and geldings. Multiple studies have also demonstrated positive effects on racing careers for horses that commence racing at a younger age. However, the applicability of these studies to small, native racing populations is unknown and warrants investigation. Objective: To provide summary statistics for performance outcomes for the Norwegian-Swedish Coldblooded Trotter and to document and provide evidence on the current differences in racing careers across age at first start groups, s...
Associations of health status and conformation with longevity and lifetime competition performance in young Swedish Warmblood riding horses: 8,238 cases (1983-2005). To determine associations of health status and conformation with competition longevity and lifetime performance in young Swedish Warmblood riding horses. Methods: Cohort study and genetic analysis. Methods: 8,238 horses. Methods: Horses were examined for health, conformation, and performance from 1983 to 2005, when they were 4 to 5 years old, and competition results from 1983 to 2012 were evaluated. Associations between conformation, health, and talent scores of young horses and longevity (years in competition) and lifetime performance were analyzed. Odds ratios of competing later in life amon...
Evaluation of intra-abdominal pressure in horses that crib. To measure intra-abdominal pressure (IAP) in horses that crib and compare it with IAP in horses that do not have this vice. Methods: Cohort study. Methods: Healthy cribbing horses (cribbing cohort, n = 8) and 8 healthy noncribbing horses (noncribbing cohort). Methods: A microsensor catheter was introduced into the peritoneal cavity through the right paralumbar fossa, using local anesthesia, for measurement of IAP. These pressures were recorded in 1-minute intervals for 2 hours, while the horses were standing tied in a stall. IAPs of cribbing horses were compared to the noncribbing cohort...
Exercise affects joint injury risk in young Thoroughbreds in training. The aim of this study was to identify exercise-related risk factors for carpal and metacarpo- and metatarso-phalangeal (MCP/MTP) joint injury occurrence in young Thoroughbreds in flat race training. In a 2-year prospective cohort study, daily exercise and joint injury data were collected from horses in 13 training yards in England. Four injury categories were defined: (1) localised to a carpal or MCP/MTP joint based on clinical examination and/or use of diagnostic analgesia with no diagnostic imaging performed; (2) localised to a carpal or MCP/MTP joint with no abnormalities detected on diagno...
Effects of various presale radiographic findings for yearling Thoroughbreds on 2-year-old racing performance. To determine the effects of various presale radiographic findings for Thoroughbreds sold at a yearling sale on 2-year-old racing performance of those horses. Methods: 397 Thoroughbreds. Methods: Cohort study. Methods: Thoroughbreds offered for sale at a Thoroughbred sales facility in Kentucky were selected via a randomization procedure. Effects of various presale radiographic findings on the following measures of 2-year-old racing performance were determined: having started a race and having placed (ie, finished in first, second, or third place) in a race at least once, total amount of money e...
The effect of interruptions during training on the time to the first trial and race start in Thoroughbred racehorses. Few studies have investigated the effect of having interruptions during training on future training and racing performance in Thoroughbred racehorses. The aim of this paper was to investigate the effect of having an interruption before the first trial on starting in a trial or a race. A prospective cohort study was used to record the training activity of a cohort of Thoroughbred racehorses, over two racing seasons. Fourteen racehorse trainers recorded information on the distances worked at canter and at fast speeds (<15s/200 m) and provided reasons for horses not training, or for having int...
Seasonal variation in results of diagnostic tests for pituitary pars intermedia dysfunction in older, clinically normal geldings. To determine whether seasonal variations exist in endogenous plasma ACTH, plasma α-melanocyte-stimulating hormone (α-MSH), serum cortisol, and serum insulin concentrations and in the results of a dexamethasone suppression test for older, clinically normal geldings in Alabama. Methods: Cohort study. Methods: 15 healthy mixed-breed geldings (median age, 14 years). Methods: Sample collection was repeated monthly for 12 months. Dexamethasone (0.04 mg/kg [0.02 mg/lb], IM) was administered and cortisol concentrations were determined at 15 and 19 hours. Radioimmunoassays were used to measure ACTH, ...
Factors associated with mortality of geriatric horses in the United Kingdom. Geriatric horses (aged≥15 years) now represent a substantial proportion of the equine population, yet mortality rates for aged horses in the UK have not previously been described. Although post-mortem studies have provided some data regarding specific causes of death, "old age" is a common owner-reported reason for euthanasia of adult horses, indicating further elucidation of reasons for death or euthanasia is required for the geriatric equine population. The objective of this cohort study was to describe mortality rates, causes of death or euthanasia and factors associated with mortality in...
Exercise in Thoroughbred yearlings during sales preparation: a cohort study. There is increasing evidence suggesting that early exercise in Thoroughbred racehorses may be beneficial to the development of the musculoskeletal system. At present, information on the exercise programmes and health problems of individual yearlings during a sales preparation is scant. Objective: To describe the exercise and health problems of Thoroughbred yearlings during preparation for sales, and to identify variations in exercise between and within farms. Methods: A prospective cohort study was used to collect exercise and health information from 18 farms across New Zealand. Daily exercise...
Evaluation of plasma ACTH, alpha-melanocyte-stimulating hormone, and insulin concentrations during various photoperiods in clinically normal horses and ponies and those with pituitary pars intermedia dysfunction. To measure plasma ACTH, alpha-melanocyte-stimulating hormone (aloha-MSH), and insulin concentrations during various photoperiods between February and October in horses and ponies with and without pituitary pars intermedia dysfunction (PPID). Methods: Cohort study. Methods: 13 clinically normal (control) ponies, 14 clinically normal (control) horses, 7 ponies with PPID, and 8 horses with PPID. Methods: Blood samples were collected from February through October during 8 photoperiods: 1, February 13 through March 2; 2, April 4 through 6; 3, June 19 through 22; 4, August 6 through 7; 5, August 14 ...
Descriptive epidemiology of fracture, tendon and suspensory ligament injuries in National Hunt racehorses in training. While fractures and tendon injuries are known to be important diseases in National Hunt (NH) racehorses during racing, there are no accurate estimates of their incidence in NH training yards. Objective: To estimate the incidence of fractures and tendon and suspensory ligament injuries (TLIs) in NH racehorses in training; to describe the injuries incurred and to compare injury incidence rates by horse age, trainer, gender and background (ex-flat vs. ex-store horses). Methods: Cohort data were collected from 14 UK NH training yards for 2 racing seasons. Daily exercise regimens and details of fra...
Payments to injured professional jockeys in British horse racing (1996-2006). To determine the direct and indirect cost of injuries in professional jockeys as a result of race riding. Methods: Cohort study. Methods: Professional horse racing. Methods: Professional jockeys in the UK registered with the Jockey Club. Methods: Payouts under the Professional Riders Insurance Scheme (PRIS) for injuries sustained by professional jockeys, which were recorded by the Jockey Club injury database between 1996 and 2006 inclusive. Results: In the 11-year period of the study, there were 1328 injuries that resulted in jockeys missing a total of 71,509 days of racing, and as a result PR...