Topic:Case-Control Study
A case-control study is a type of observational research design used to identify and evaluate factors that may contribute to a particular outcome by comparing subjects with a specific condition (cases) to those without the condition (controls). In equine research, case-control studies are employed to investigate various health-related issues affecting horses, such as disease outbreaks, lameness, or behavioral disorders. These studies help identify potential risk factors or associations by analyzing the differences in exposure or characteristics between the two groups. This page compiles peer-reviewed research studies and scholarly articles that explore the methodology, application, and findings of case-control studies in equine science, providing insights into their role in advancing equine health and management practices.
Does inbreeding contribute to pregnancy loss in Thoroughbred horses? Excessive inbreeding increases the probability of uncovering homozygous recessive genotypes and has been associated with an increased risk of retained placenta and lower semen quality. No genomic analysis has investigated the association between inbreeding levels and pregnancy loss. Objective: To compare genetic inbreeding coefficients (F) of naturally occurring Thoroughbred Early Pregnancy Loss (EPLs), Mid and Late term Pregnancy Loss (MLPL) and Controls. The F value was hypothesised to be higher in cases of pregnancy loss (EPLs and MLPLs) than Controls. Methods: Observational case-control st...
Breath characteristics and adventitious lung sounds in healthy and asthmatic horses. Standard thoracic auscultation suffers from limitations, and no systematic analysis of breath sounds in asthmatic horses exists. Objective: First, characterize breath sounds in horses recorded using a novel digital auscultation device (DAD). Second, use DAD to compare breath variables and occurrence of adventitious sounds in healthy and asthmatic horses. Methods: Twelve healthy control horses (ctl), 12 horses with mild to moderate asthma (mEA), 10 horses with severe asthma (sEA) (5 in remission [sEA-], and 5 in exacerbation [sEA+]). Methods: Prospective multicenter case-control study. Horses w...
Lumbar vertebral bone density is decreased in horses with pituitary pars intermedia dysfunction. Pathological fractures have been reported in equids with pituitary pars intermedia dysfunction (PPID) but their prevalence and pathogenesis is unknown. Objective: To compare: (1) bone mineral density (BMD) in weight bearing and nonweight bearing bones in PPID+ equids and aged and young PPID- controls; and (2) biomechanical properties of the fourth lumbar vertebral body in PPID+ equids and aged PPID- equids. Methods: Case-control study: five PPID+ equids and six aged and four young PPID- control horses. Methods: PPID status was based on clinical signs and necropsy examination of the pituitary g...
Severe asthma in horsed is associated with increased airway innervation. Altered innervation structure and function contribute to airway hyperresponsiveness in human asthma, yet the role of innervation in airflow limitation in asthma in horses remains unknown. Objective: To characterize peribronchial innervation in horses with asthma. We hypothesized that airway innervation increases in horses with asthma compared with controls. Methods: Formalin-fixed lung samples from 8 horses with severe asthma and 8 healthy horses from the Equine Respiratory Tissue Biobank. Ante-mortem lung function was recorded. Methods: Blinded case-control study. Immunohistochemistry was per...
Incidence and risk factors for complications associated with equine general anaesthesia for elective magnetic resonance imaging. Complications are a practical consideration for elective magnetic resonance imaging (MRI) studies performed under general anaesthesia but relatively little is known about their distribution and risk factors. Objective: To describe the incidence of complications associated with MRI performed under general anaesthesia at a large referral facility and evaluate potential risk factors for these complications. Methods: Retrospective case-control study. Methods: Patient information and details of the MRI procedure were collected retrospectively from medical records of all horses that had undergone an...
Fecal microbiota transplant for treatment of diarrhea in adult hospitalized horses-111 cases (2013-2018). Fecal microbiota transplant (FMT) is increasingly administered as part of the treatment of colitis in horses, yet there is little data as to its effectiveness. Retrospective evaluation of the effects of FMT on discharge status, fecal consistency, length of hospitalization, and improvement in clinical signs in horses hospitalized for diarrhea. Retrospective case-control study. Medical records of adult horses (>1 year old) that received at least one transfaunation treatment (2013-2018) in two referral hospitals were identified through a medical records database search. Medical records of contemp...
The fecal bacterial microbiota of healthy and sick newborn foals. The fecal bacterial microbiota of normal foals and foals with enterocolitis has been characterized using next-generation sequencing technology; however, there are no reports investigating the gut microbiota in foals hospitalized for other perinatal diseases. Objective: To describe and compare the fecal bacterial microbiota in healthy and sick foals using next-generation sequencing techniques. Methods: Hospitalized (17) and healthy foals (21). Methods: Case-control study. Fecal samples were collected from healthy and sick foals on admission. Sick foals were further divided into sick nonseptic (...
Catastrophic Musculoskeletal Injuries in Thoroughbred Racehorses in Uruguay, 2011-2017. Catastrophic musculoskeletal injuries (CMI) pose a major welfare concern to horses and their riders, yet limited data are available describing their occurrence in South America. Using a retrospective cohort and case-control design, the objective of the study was to determine the incidence of CMI for Thoroughbreds in training and racing, and associated horse-level risk factors in Uruguay. Seventy-seven Thoroughbreds sustained a CMI, 37 of which were age- and sex-matched to 111 control horses in the same race. Training and racing data from 2011 to 2017 were collected. Incidence of race day CMI p...
Changes in Thoroughbred speed and stride characteristics over successive race starts and their association with musculoskeletal injury. Certain stride characteristics have been shown to affect changes in biomechanical factors that are associated with injuries in human athletes. Determining the relationship between stride characteristics and musculoskeletal injury (MSI) may be key in limiting injury occurrence in the racehorse. Objective: This study aimed to determine whether changes in race day speed and stride characteristics over career race starts are associated with an increased risk of MSI in racehorses. Methods: Case-control study. Methods: Speed, stride length, and stride frequency data were obtained from the final 200â...
Airway remodeling in horses with mild and moderate asthma. There is a remodeling of the central airways in horses with severe asthma but whether a similar process occurs in horses with the mild or moderate asthma (MMA) is unknown. Objective: To evaluate lesions affecting the central airways of horses with MMA. Methods: Twelve horses with MMA and 8 control horses. Methods: Case-control retrospective study of horses classified as MMA affected or controls based on history and bronchoalveolar lavage fluid cytology. Endobronchial biopsies were analyzed using histomorphometry and a semiquantitative histologic scoring system. Results: Histomorphometry identi...
Horses vaccinated with live attenuated intranasal strangles vaccine seroconvert to SEQ2190 and SeM. The dual antigen iELISA uses two Streptococcus equi subsp equi surface protein antigens composed of N-terminal portions of SEQ2190 (Antigen A) and SeM (Antigen C). It is currently used to identify animals exposed to S. equi which have developed an immune response to the target antigens. Objective: To determine the usefulness of the dual antigen iELISA in a population of horses vaccinated with Pinnacle IN. We hypothesised that horses vaccinated for strangles with a live attenuated, non-encapsulated SeM-2 strain of S. equi, would seroconvert when tested 5 weeks later by the dual antigen iELIS...
Factors associated with survival and racing performance of 114 Thoroughbred foals with septic arthritis compared with maternal siblings (2009-2015). There is little consensus on factors associated with survival in foals with septic arthritis and limited data on long-term racing performance of Thoroughbred foals treated for septic arthritis. A more thorough understanding of short- and long-term outcome is necessary to help inform owners, and subsequently guide treatment. Objective: To investigate factors associated with survival, and to analyse racing performance of foals with septic arthritis compared with their maternal siblings. Methods: Retrospective cohort and a case-control study. Methods: Veterinary clinical records of Thoroughbred f...
Pathology, infectious agents and horse- and management-level risk factors associated with signs of respiratory disease in Ethiopian working horses. Respiratory disease is a common cause for presentation of working horses to clinics in Ethiopia and a priority concern for owners. Objective: To identify risk factors for and association of pathogens with respiratory signs in working horses. Methods: Unmatched case-control study. Methods: Cases were those animals recently coughing (last 7Â days) or observed with coughing, nasal discharge or altered respiration at the time of examination. A physical exam and respiratory endoscopy were performed including a tracheal wash sample to detect the presence of pathogens and serology performed on blood....
The Influence of Hippotherapy on the Body Posture in a Sitting Position among Children with Cerebral Palsy. The purpose of this study was to assess the influence of hippotherapy (therapy with horses) on posture and body function among children with cerebral palsy. A case-control study included forty-five children aged 6-12 years, classified as Gross Motor Function Classification System (GMFCS) level I or II, with spastic diplegia or hemiplegia. The participants were randomly divided into three groups: study I (n = 15), study II (n = 15) and control (n = 15). The children from the study groups attended 30min hippotherapy sessions for 12 consecutive weeks, twice (study group I) or once (study group II...
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,...
Tracheal microbial populations in horses with moderate asthma. There are limited data on potential dysbiosis of the airway microbiota in horses with asthma. Objective: We hypothesized that the respiratory microbiota of horses with moderate asthma is altered. Our objectives were (a) to quantify tracheal bacterial populations using culture and qPCR, (2) to compare aerobic culture and qPCR, and (c) to correlate bacterial populations with bronchoalveolar lavage fluid (BALF) cytology. Methods: Eighteen horses with moderate asthma from a hospital population and 10 controls. Methods: Prospective case-control study. Aerobic culture was performed on tracheal aspir...
Risk factors for shedding of Salmonella enterica among hospitalized large animals over a 10-year period in a veterinary teaching hospital. Transmission of Salmonella in veterinary hospitals is typically associated with environmental contamination. Links between isolates recovered from hospitalized large animals and environment suggest animals as the likely source. Therefore, understanding factors influencing shedding is key in control. Shedding in hospitalized animals has been investigated, but many studies focused on subsets of animals limiting generalizability. Objective: (1) Investigate factors associated with fecal shedding of Salmonella among hospitalized large animals at a veterinary hospital. (2) Compare results obtained u...
Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses. Variation in equine caudal cervical spine morphology at C6 and C7 has high prevalence in Warmblood horses and is suspected to be associated with pain in a large mixed-breed group of horses. At present no data exist on the relationship between radiographic phenotype and clinical presentation in Warmblood horses in a case-control study. Objective: To establish the frequency of radiographically visible morphologic variation in a large group of Warmblood horses with clinical signs and compare this with a group without clinical signs. We hypothesised that occurrence of morphologic variation in the ...
Relationship Between Historical Lameness, Medication Usage, Surgery, and Exercise With Catastrophic Musculoskeletal Injury in Racehorses. The rate of catastrophic musculoskeletal injuries (CMI) in racehorses is high in the United States compared to other countries. Few modifiable risk factors related to lameness, medication, and surgery history have been identified. To detect management factors that increase risk of CMI by comparing medical histories between horses that sustained, and horses that did not sustain, a CMI. Case-control. Racehorse necropsy data (May 2012-June 2013) were obtained through the California Horse Racing Board Postmortem Program. Attending veterinarians of Thoroughbreds (TB) and Quarter Horses (QH) tha...
Metabolic perturbations in Welsh Ponies with insulin dysregulation, obesity, and laminitis. Metabolomics, the study of small-molecule metabolites, has increased understanding of human metabolic diseases, but has not been used to study equine metabolic syndrome (EMS). Objective: (1) To examine the serum metabolome of Welsh Ponies with and without insulin dysregulation before and during an oral sugar test (OST). (2) To identify differences in metabolites in ponies with insulin dysregulation, obesity, or history of laminitis. Methods: Twenty Welsh Ponies (mean ± SD; 13.8 ± 9.0 years) classified as non-insulin dysregulated [CON] (n = 10, insulin  60 mU/L) at 75 minutes ...
The Impact of a Horse Riding Intervention on the Social Functioning of Children with Autism Spectrum Disorder. This paper reports a case-control study of a horse riding intervention for children with autism spectrum disorder (ASD). A sample of 26 children, aged 6 to 9 years, were assigned to either the intervention ( = 12) or control group conditions ( = 14). Pre- and post-tests were carried out using the Childhood Autism Rating Scale, Second Edition (CARS2) and the Aberrant Behaviour Checklist-Community Edition (ABC-C). An observational measure of compliance and behaviour during the horse riding sessions was completed for the intervention group. There was a significant reduction in the severity of ASD...
Toxoplasma gondii seroprevalence and association with equine protozoal myeloencephalitis: A case-control study of Californian horses. While toxoplasmosis is not commonly considered a clinical disease of equines, previous seroprevalence studies have reported differing background rates of Toxoplasma gondii infection in horses globally. The objective of this study was to evaluate possible associations between T. gondii seroprevalence and clinical signs of equine protozoal myeloencephalitis (EPM) in horses. Using a case-control study design, 720 Californian horses with neurologic signs compatible with EPM were compared to healthy, non-neurologic horses for the presence of T. gondii antibodies (using indirect fluorescent antibody...
Cardiac findings in Quarter Horses with heritable equine regional dermal asthenia. OBJECTIVE To compare biomechanical and histologic features of heart valves and echocardiographic findings between Quarter Horses with and without heritable equine regional dermal asthenia (HERDA). DESIGN Prospective case-control study. ANIMALS 41 Quarter Horses. PROCEDURES Ultimate tensile strength (UTS) of aortic and mitral valve leaflets was assessed by biomechanical testing in 5 horses with HERDA and 5 horses without HERDA (controls). Histologic evaluation of aortic and mitral valves was performed for 6 HERDA-affected and 3 control horses. Echocardiography was performed in 14 HERDA-affected...
Evaluation of coagulation and fibrinolysis in horses with atrial fibrillation. To evaluate horses with atrial fibrillation for hypercoagulability; plasma D-dimer concentrations, as a marker of a procoagulant state; and a relationship between coagulation profile results and duration of atrial fibrillation or presence of structural heart disease. Methods: Case-control study. Methods: Plasma samples from 42 horses (25 with atrial fibrillation and 17 without cardiovascular or systemic disease [control group]). Methods: Results of hematologic tests (ie, plasma fibrinogen and D-dimer concentrations, prothrombin and activated partial thromboplastin times, and antithrombin activ...
Equine grass sickness in Scotland: A case-control study of environmental geochemical risk factors. We hypothesised that the apparent geographical distribution of equine grass sickness (EGS) is partly attributable to suboptimal levels of soil macro- and trace elements in fields where EGS occurs. If proven, altering levels of particular elements could be used to reduce the risk of EGS. Objective: To determine whether the geographical distribution of EGS cases in eastern Scotland is associated with the presence or absence of particular environmental chemical elements. Methods: Retrospective time-matched case-control study. Methods: This study used data for 455 geo-referenced EGS cases and 910 ...
Lamellar pathology in horses with pituitary pars intermedia dysfunction. Hoof lamellar pathology in horses with pituitary pars intermedia dysfunction (PPID) has not been described previously. Objective: To describe the histomorphometry and pathological lesions in hoof lamellar tissue of animals that had PPID with or without concurrent laminitis, with reference to age-matched controls. We hypothesised that lamellar lesions consistent with laminitis would be associated with PPID, even in animals without current or historical laminitis. Methods: Prospective case-control study. Methods: Mid-dorsal hoof histological sections were obtained post mortem from the forelimbs ...
Acute phase proteins in racehorses with inflammatory airway disease. Systemic inflammation is observed in horses with heaves and could also be present in horses with a lesser degree of pulmonary inflammation. Objective: It was hypothesized that racehorses with inflammatory airway disease (IAD) have increased concentration of circulating acute phase proteins. The objective of this study was to compare serum acute phase proteins of racehorses with and without lower airway inflammation. Methods: Serum from 21 client-owned Standardbred racehorses with exercise intolerance and lower airway inflammation and serum from 10 client-owned Standardbred racehorses with exer...
Association of catastrophic biaxial fracture of the proximal sesamoid bones with bony changes of the metacarpophalangeal joint identified by standing magnetic resonance imaging in cadaveric forelimbs of Thoroughbred racehorses. To compare bony changes in the metacarpophalangeal joint (MCPJ) of racehorses with (cases) and without (controls) biaxial proximal sesamoid bone (PSB) fracture as determined by 2 grading scales applied to images of cadaveric forelimbs obtained by means of standing MRI (sMRI). Methods: Case-control study. Methods: Forelimbs from 74 Thoroughbred racehorses (21 cases and 53 controls) that were euthanized at a Florida racetrack. Methods: Both forelimbs were harvested from cases and controls. Each forelimb underwent sMRI to obtain images of the MCPJ. Two grading scales were described and used for i...
Quantitative assessment of the equine hoof using digital radiography and magnetic resonance imaging. Evaluation of laminitis cases relies on radiographic measurements of the equine foot. Reference values have not been established for all layers of the foot. Objective: To establish normal hoof wall and sole measurements using digital radiography (DR) and magnetic resonance imaging (MRI) and to document tissue components present in the dorsal hoof wall and solar layers seen on DR. Methods: Prospective observational case-control study. Methods: Digital radiography and MRI were performed on 50 cadaver front feet from 25 horses subjected to euthanasia for nonlameness-related reasons. Four observer...
Caudal lumbar vertebral fractures in California Quarter Horse and Thoroughbred racehorses. To gain insight into the pathophysiology of equine lumbar vertebral fractures in racehorses. Objective: To characterise equine lumbar vertebral fractures in California racehorses. Methods: Retrospective case series and prospective case-control study. Methods: Racehorse post mortem reports and jockey injury reports were retrospectively reviewed. Vertebral specimens from 6 racehorses affected with lumbar vertebral fractures and 4 control racehorses subjected to euthanasia for nonspinal fracture were assessed using visual, radiographic, computed tomography and histological examinations. Results: ...