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Topic:Clinical Study
Clinical studies in equine research involve the systematic investigation of health and disease in horses through structured scientific methods. These studies aim to evaluate the safety and efficacy of treatments, understand disease mechanisms, and improve veterinary care practices. Clinical studies can include randomized controlled trials, observational studies, and case-control studies. They may focus on various aspects such as pharmacokinetics, therapeutic interventions, and diagnostic techniques. This page compiles peer-reviewed research studies and scholarly articles that explore the design, implementation, and findings of clinical studies in equine medicine, providing insights into their impact on horse health and veterinary practices.
The macroscopic vascular anatomy of the equine ethmoidal area. The vascular anatomy of the ethmoidal area in six normal horses and two normal ponies was studied using vascular-corrosion casts. The major arterial supply to the ethmoidal area stems from an intracranial source. The internal and external ethmoidal arteries anastomose on the rostral intracranial surface of the cribriform plate to form the arterial ethmoidal rete which arborizes and passes through the perforations of the cribriform plate to supply the ethmoid labyrinth. A minor arterial supply to the ventral portion of the ethmoid labyrinth stems from a small caudal nasal branch of the sphenopa...
Iridium-192 interstitial brachytherapy for equine periocular tumours: treatment results and prognostic factors in 115 horses. One hundred and fifteen horses with periocular tumours were treated with iridium-192 interstitial brachytherapy. Tumours included squamous cell carcinomas (n = 52) and sarcoids (n = 63). All horses were scheduled to receive 60 Gy (minimal tumour dose) given at a low dose rate (0.034 +/- 0.010 Gy/h). The mean and median follow-up times to last contact or death were 24 and 16 months, respectively. Chronic radiation reactions included palpebral fibrosis (10.4%), cataract (7.8%), keratitis and corneal ulceration (6.9%). Cosmetic changes included permanent epilation (21.7%) and hair dyspigmentation...
The reappearance of strongyle eggs in faeces of horses treated with pyrantel embonate. The reappearance of strongyle eggs in the faeces of horses treated with pyrantel embonate was studied. The horses (103) were divided in 11 groups on 8 different farms. The efficacy of pyrantel embonate against strongyles, based on egg count reduction tests, was 99.8%. Mean weekly egg counts performed between week 2 and week 9 after treatment showed that 5 weeks after treatment the egg output passed the 90% reduction level. It is concluded that strategic treatments of horses with pyrantel embonate for the prevention of strongylosis should be administered with intervals of 6 weeks.
Development of PCR assays to detect genetic variation amongst equine herpesvirus-1 isolates as an aid to epidemiological investigation. A search for variable restriction sites has been carried out for equine herpesvirus-1 (EHV-1) in an attempt to develop markers which can be used to group epidemiologically related viruses into groups, and to learn more about the dynamics of EHV-1 disease. Crude viral DNA extracts of EHV-1, prepared by Hirt extraction, were digested with AluI, HaeIII, or RsaI, and Southern blotted following electrophoresis. DNA fingerprints, produced by probing the Southern blots with the EHV-1 EcoR1-I fragment, separated 56 isolates into 16 groups. The variable sites within the EcoR1-I fragment were mapped app...
Regulation of respiratory muscle activities during chemoreceptor stimulation in adult horses. We examined the electromyographic activity of the costal portion of the diaphragm and the transverse abdominal and external oblique muscles in 6 chronically instrumented awake adult horses during eupneic breathing, during 2 levels of hypercapnia (fractional concentration of inspired CO2; FICO2 = 0.4 and 0.6), and during 2 levels of hypocapnic hypoxia (FIO2 = 0.15 and 0.12). Using the inert gas technique, we also measured the end-expiratory lung volumes of the 6 horses during eupnea, 6% CO2 challenge, and 12% O2 breathing. During eupneic breathing, phasic electrical activity of these 3 muscles ...
Local and remote matrix responses to chondrocyte-laden collagen scaffold implantation in extensive articular cartilage defects. Chondrocyte-laden collagen scaffolds were evaluated in extensive cartilage defects in an equine model. Arthroscopic techniques were used to implant a chondrocyte-collagen culture product in 15-mm defects in the lateral trochlear ridge of the femoropatellar joint of 12 horses. Ungrafted control defects were formed in the opposite joint. Groups of six horses were terminated at 4 and 8 months after implantation and the repair sites, adjacent cartilage, and remote cartilage within each femoropatellar joint examined biochemically. Eight months following surgery the relative proportions of type II c...
Evaluation of propofol as a general anesthetic for horses. This study provides baseline information on the potential use of propofol as a general anesthetic for horses. Using a Latin square design, propofol (2, 4, and 8 mg/kg) was administered intravenously on three separate occasions to six mature horses. Information about anesthetic induction, duration, and recovery was recorded along with results of rectal temperature, heart rate, respiratory rate, pHa, PaCO2 and PaO2. Statistical analysis included a mixed model analysis of variance, a general linear model analysis and least square means test for post hoc comparisons. A P < .05 was considered si...
Epidemiological risk factors associated with a diagnosis of clinical cyathostomiasis in the horse. Multiple logistic regression was used to assess epidemiological risk factors associated with the diagnosis of cyathostomiasis in 87 cases of chronic diarrhoea in the horse. Age, season and the period since last receiving anthelmintics were identified as important risk factors using chi-square and two-sample t test analyses, whereas access to grazing, shared grazing with other horses and recurrence of signs were only weakly associated with a diagnosis of cyathostomiasis. Multivariate analysis of the parameters using logistic regression was performed. The final model included age, season and tim...
Intraperitoneal use of sodium carboxymethylcellulose in horses undergoing exploratory celiotomy. The effect of intraperitoneal sodium carboxymethylcellulose (SCMC) administration on clinical outcome and survival was evaluated in horses undergoing exploratory celiotomy for acute gastrointestinal disease. Comparison of variables was made retrospectively between 44 horses that had SCMC and 92 horses (controls) not treated with SCMC. Mean age, body weight, heart rate, packed cell volume and plasma total protein of horses at admission, and convalescent period were not significantly different between control and SCMC groups. No significant differences were noted between control horses and SCMC ...
Endoscopy of the upper respiratory tract during treadmill exercise: a clinical study of 100 horses. Endoscopy of the upper respiratory tract was performed in 100 horses during high speed treadmill exercise. Reasons for endoscopy were a history of an abnormal noise during exercise in 75 horses, poor performance in 17 horses and to evaluate the results of upper respiratory tract surgery in 8 horses. Of the 75 horses with a history of an abnormal noise during exercise the cause was determined in 67 (89%). Endoscopic abnormalities were detected at rest in 40 of these 75 horses (53%). In these 40 horses, a similar diagnosis as to the cause of the abnormal noise was made at rest and during exercis...
Vascular supply of the tendon of the equine deep digital flexor muscle within the digital sheath. The vascular and microvascular anatomy of the equine deep digital flexor tendon (DDFT) within the digital sheath was studied by injecting the vasculature with either colored latex or barium sulphate for radiographic, microangiographic, histologic, and computed tomographic (CT) evaluation. Consecutive 4-mm thick two-dimensional CT slice data were reconstructed to 3-dimensional volumetric images to enhance spatial evaluation of the blood supply. Gross dissection and angiographic studies identified three major vascular sources. Above the fetlock, the DDFT was supplied by either a branch of the me...
Development of a colic severity score for predicting the outcome of equine colic. Thirty-two physical examination and laboratory variables were recorded during examination of 165 horses admitted for acute abdominal disease. Univariate analyses were performed to determine which of the variables were significantly different between horses that lived or died. Stepwise logistic regression was performed to identify variables with the best predictive value. Four variables (heart rate, peritoneal fluid total protein concentration, blood lactate concentration, and abnormal mucous membrane) remained significant when entered into the model. Histograms for each significant variable we...
Evaluation of Directigen Flu A assay for detection of influenza antigen in nasal secretions of horses. The Directigen Flu A assay (Becton Dickinson, Microbiology Systems, Mississauga, Ontario, Canada) is a commercially available immunoassay designed for rapid in vitro recognition of influenza A nucleoprotein. The purpose of this study was to evaluate this assay for detection of influenza virus in nasal secretions of naturally infected horses. The assay was shown to react with representative strains of influenza virus which cause disease in horses and did not react with nasal secretions from uninfected horses kept in isolation. Between 33% and 45% of nasal secretions specimens obtained from clin...
Anti-collagen antibodies and immune complexes in equine joint diseases. An investigation was made into the possible contribution of autoimmune mechanisms to equine arthropathies. Serum and synovial fluid (SF) immune complexes and anti-collagen Type II antibodies were measured, by ELISA, in groups of horses with naturally occurring osteoarthritis (OA), osteochondritis dissecans (OCD), bone fracture, traumatised joints, synovitis, infected joints and non-diseased (control) joints. Significantly raised anti-collagen Type II antibodies were found in osteoarthritic (P < 0.02) and traumatised joint synovial fluids (P < 0.01) compared with the control, where ten of...
Treatment of atrial fibrillation in horses: new perspectives. Forty-one horses were treated for atrial fibrillation (AF) with 22 mg/kg quinidine sulfate via nasogastric tube every 2 hours until conversion to sinus rhythm, a cumulative dose of 88 to 132 mg/kg had been administered in 2-hour increments, or the horse had adverse or toxic effects from the drug. Treatment intervals were prolonged to every 6 hours if conversion had not occurred. Digoxin was administered before treatment if the horse had a fractional shortening < or = 27% (3 horses), was prone to tachycardia (resting heart rate > or = 60 beats/min) (1 horse), or had a previous history of sustai...
Transection of the accessory ligament of the superficial digital flexor muscle for the treatment of superficial digital flexor tendinitis in standardbreds: 40 cases (1988-1992). Medical records of 40 racing Standardbreds with superficial digital flexor tendinitis that underwent transection of the accessory ligament of the superficial digital flexor (SDF) muscle (superior check desmotomy) were reviewed. Surgery was performed bilaterally in 32 horses and unilaterally in 8. Concurrent palmar annular desmotomy was performed in 8 horses in which tendinitis involved the distal metacarpal region and confinement of the deep and SDF tendons by the annular ligament was suspected. Follow-up information was obtained for 32 horses, by telephone, and racing results were available f...
Quantitative electroencephalographic evaluation to determine the quality of analgesia during anesthesia of horses for arthroscopic surgery. We compared the anesthetic combination of detomidine, ketamine, and halothane in control horses not undergoing apparently painful procedures with that in horses during arthroscopic surgery. The effectiveness of this regimen in suppressing neurologic response to surgery was, thus, evaluated. In this study, significant differences were not observed in electroencephalographic total amplitude, spectral edge, or beta-to-delta frequency ratio between surgically treated and nonsurgically treated (control) horses. On the basis of its attenuation of encephalographic responses, we conclude that detomidi...
Behavioural studies in healthy ponies subjected to short-term forced recumbency aiming at an adjunctive treatment in an acute attack of laminitis. The authors postulated that a period of forced recumbency during an acute attack of laminitis may counteract the disabling effects on the secondary epidermal laminae. On the basis of this concept a study was made of the behavior of three healthy Shetland ponies when placed in a box in which the ceiling was too low for a standing position but allowed comfortable sternal recumbency. When the height of the box was about 125% of the vertical distance between the withers and the sternum, the ponies lay calmly during most of the experimental period and the rare attempts at rising did not seem to put...
Radiographic and endoscopic study of horses performing an oral based stereotypy. There is confusion in the veterinary literature concerning the definition of oral based stereotypies in the horse. This study reports the use of fluoroscopy and endoscopy during cribbiting/wind-sucking in afflicted horses. This permitted observations of movements of the pharyngeal and oesophageal tissues and of the air column within during the stereotypic behaviour. The findings reported show that the sequence of events during crib-biting/wind-sucking is not related to deglutition and that air is not swallowed to the stomach. Transient dilation of the upper oesophagus was recorded and the char...
Acetylcholine release from airway cholinergic nerves in horses with heaves, an airway obstructive disease. The present study was conducted to determine if acetylcholine (ACh) release from airway cholinergic nerves is increased and if modulation of ACh release by prejunctional receptors is altered in horses with heaves, an obstructive airway disease characterized by airway inflammation and bronchospasm. Trachealis strips and bronchial segments of normal horses and horses affected with heaves were suspended in 2-ml tissue baths. ACh release was induced by electrical field stimulation and the bath ACh content was measured by high performance liquid chromatography (HPLC) with electrochemical detection....
Histological changes in the uterus during postpartum in the mare. An histological study of the postpartum period in 29 mares was carried out. Uterine biopsies were taken daily during the first 10 days postpartum in a total of 87 samples. At day 0, equine endometrium was characterized in the surface by the presence of regularly ordered microcaruncles; the stratum spongiosum was oedematous and contained distended and scarce glands. Degenerative changes in microcaruncles and endometrial glands were present on day 1 postpartum. The epithelium of the microcaruncles from 2 to 5 days postpartum showed cytoplasmic vacuolization, karyorrhexis and an inflammatory reac...
Exercise induced ventilation/perfusion inequality in the horse. Exercise in normal human subjects causes deterioration of matching of ventilation to blood flow in the lungs, but only in about 50% of those examined. A previous study (Wagner et al. 1989) of 5 horses showed no significant worsening of ventilation/blood flow (VA/Q) relationships during heavy exercise as determined by multiple inert gas elimination technique (MIGET). Because of the small number of horses in that study and the 50% human incidence of exercise induced VA/Q mismatch, we studied an additional 6 Thoroughbreds, comparing VA/Q relationships at the walk (1.4 m/s, 0 degrees incline) and ...
Distribution of inspired gas to each lung in the anaesthetised horse and influence of body shape. The distribution of inspired gas to each lung, time constants of the lungs and parameters of gas exchange were studied in 2 groups of horses (mean bwt 606 kg), anaesthetised using thiopentone and chloral hydrate and breathing room air. One group (n = 4) had a downward curved abdominal contour (round-bellied) and the other group (n = 4) had an upward curved abdominal contour (flat-bellied). An equal distribution of inspired gas between the lungs existed in both groups in dorsal recumbency. Flat-bellied horses maintained this equal distribution in lateral recumbency whereas in round-bellied hors...
Case-control study of the association between various management factors and development of colic in horses. Texas Equine Colic Study Group. The association between various management factors and development of colic was studied in 821 horses treated for colic and 821 control horses treated for noncolic emergencies by practicing veterinarians in Texas between Oct 1, 1991 and Dec 31, 1992. History of previous colic and history of previous abdominal surgery were found to be significantly associated with colic. Change in stabling conditions during the 2 weeks prior to the time of examination, recent change in diet, and recent change in level of activity significantly increased the risk for development of colic. Changes in activity lev...
[Intravenous administration of Ivomec in horses]. Now and then cases have been reported where horses died suddenly after intravenous application of Ivomec. Lethal anaphylactic reactions in horses are known to occur incidentially after intravenous application of drug dissolved in propyleneglycol or glycerolformol. Since Ivomec is registered for use in cattle, sheep and pig, its use in horses has to be regarded as 'off label use'. It is concluded that in the treatment of inhibited stages of cyathostomes ivermectin has no effect whether or not it is applied intravenously or orally. Since lethal anaphylactic reactions can occur, intravenous appli...
Amphotericin B treatment of Candida arthritis in two horses. Infectious arthritis caused by Candida spp was diagnosed in 2 horses. Source of infection was by direct inoculation in 1 horse and was presumed to be hematogenous in the other horse. On microbial culturing of synovial fluid and synovial membrane specimens, the organisms were isolated in both horses. In both horses, the joint infections resolved after i.v. administration of amphotericin B and joint drainage; however, 1 horse was eventually euthanatized because of signs of cervical pain and progressively worsening ataxia. Fungal organisms isolated on microbial culturing of joint specimens in hor...
