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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.
Advances in cooled semen technology. In the horse industry, milk or milk-based extenders are used routinely for dilution and storage of semen cooled to 4-8 degrees C. Although artificial insemination (AI) with chilled and transported semen has been in use for several years, pregnancy rates are still low and variable related to variable semen quality of stallions. Over the years, a variety of extenders have been proposed for cooling, storage and transport of stallion semen. Fractionation of milk by microfiltration, ultrafiltration, diafiltration and freeze-drying techniques has allowed preparation of purified milk fractions in ord...
Low dose insemination of mares using non-sorted and sex-sorted sperm. Mares are generally inseminated with 500 million progressively motile fresh sperm and approximately 1 billion total sperms that have been cooled or frozen. Development of techniques for low dose insemination would allow one to increase the number of mares that could be bred, utilize stallions with poor semen quality, extend the use of frozen semen, breed mares with sexed semen and perhaps reduce the incidence of post-breeding endometritis. Three low dose insemination techniques that have been reported include: surgical oviductal insemination, deep uterine insemination and hysteroscopic insemin...
Advances in cooled semen technologies: seminal plasma and semen extender. This study evaluated motility and fertility of uncentrifuged and centrifuged equine semen following dilution in a skim milk-glucose extender with or without supplemental Tyrode's medium. In addition, the effect of seminal plasma addition to each extender was evaluated. For Experiment 1, motility of 48h cooled, stored spermatozoa was evaluated following eight dilution treatments: uncentrifuged and diluted 1:4 (v/v) in skim milk-glucose extender (EZ Mixin CSTJ; CST-1:4) or in CST supplemented 65:35 (v/v) with modified Tyrode's medium (KMT-1:4); uncentrifuged and diluted to 25x10(6) spermatozoa/m...
Effects of acute intravenous aldosterone administration on Na(+), K(+), and water excretion in the horse. The effect of a temporary increase in plasma aldosterone concentration on Na(+), K(+), and water balance was investigated in four horses. Aldosterone was injected intravenously for 6 h at 20-min intervals (total 5.4 microg/kg body wt). Samples were taken for 24 h before, during, and for 48 h after the treatment. Aldosterone treatment reduced the Na(+) loss via urine and feces by 99 and 72%, respectively, later followed by a marked increase in Na(+) excretion by both pathways. During the first 6 h after the treatment, fecal K(+) excretion was elevated, and the plasma K(+) concentration was lowe...
Oral imipramine and intravenous xylazine for pharmacologically-induced ex copula ejaculation in stallions. This study is part of ongoing work toward developing pharmacological methods for enhancing and inducing ejaculation in stallions with ejaculatory dysfunction or disabilities that interfere with normal breeding behavior. The objective was to evaluate a treatment regimen involving oral imipramine followed by intravenous xylazine that, in uncontrolled field clinical trials, had shown promise for a higher rate of ejaculation and fewer side effects using a more easily obtained and administered form of imipramine. Eight stallions each underwent eight trials in which treatment consisted of imipramine...
Feeding practices associated with colic in horses. To determine whether specific feeding practices were associated with development of colic in horses. Methods: Prospective matched case-control study. Methods: 364 horses examined by veterinarians in private practice in Texas because of colic (cases; n = 182) or any other reason (controls; 182). Methods: Participating veterinarians were sent forms at the beginning of the study to collect information on signalment, feeding management practices, farm management practices, and preventive medical treatments. Case and control horses were compared by use of conditional logistic regression to identify...
Supplemental silicon increases plasma and milk silicon concentrations in horses. The primary objective of this research was to determine the effect of supplemental dietary silicon (Si) on plasma and milk Si concentrations of lactating mares and the subsequent effect on plasma Si concentrations in nursing foals. Additionally, the role of Si on altering biochemical markers of bone turnover was investigated, because supplemental Si may be advantageous in enhancing bone health. Twelve Arabian mare/foal units were pair-matched by foaling date and randomly assigned to two groups, Si-supplemented (Supplemented) or control (Control). Blood and milk samples were taken on d 0, 15, 3...
Listeria keratitis in a horse. Listeria monocytogenes is ubiquitous in the environment but is rarely reported as a cause of keratitis in animals. In this case, a mare was presented with epiphora and evidence of pain in the right eye. Listeria monocytogenes was isolated from a corneal lesion, and bacteria were also seen in the cytologic evaluation. This is the first reported case of ulcerative keratitis associated with L. monocytogenes in a horse.
Three-dimensional kinematics of the proximal interphalangeal joint: effects of raising the heels or the toe. The proximal interphalangeal joint (PIPJ) has always been considered as a low-motion joint with an almost constant angle during loading of the limb. Until very recently, its motion was not taken into account in kinematic studies in vivo. Recent in vivo studies yielded surprisingly high ranges of motion in this joint. The aim of this study was to measure, in terms of the 3 possible rotations (flexion/extension, collateromotion and axial rotation), the movements of the PIPJ in vitro during limb loading in a neutral position (500-6000 N) and after the addition of heel and toe wedges (6 degrees an...
In vivo and in vitro heel expansion in relation to shoeing and frog pressure. The objective of this study was to validate a simple method to measure the mediolateral expansion of the heels and to apply this method in an in vivo experiment. It was also the aim to quantify the mediolateral expansion in different areas of the heel using an in vitro model. In the in vitro study, 5 right and 5 left distal forelimb specimens from 5 Standardbreds were mounted vertically in a custom-made compressive test machine. The heel expansion was measured using optical kinematic analysis and a potentiometer system. Specimens were tested unshod, with frog pressure and with the weightbearin...
Assessment of gait irregularities in the horse: eye vs. gait analysis. The purpose of this study was to verify the sensitivity of 2 gait analysis methods in detecting subtle lameness and to compare the results to the traditional orthopaedic evaluation. Twenty-two horses were evaluated (1) subjectively by 3 different experienced clinicians and (2) objectively with synchronised ground reaction force and accelerometric gait measurements on a treadmill. The horses were assigned for each of the 3 methods independently to one of 3 groups (GR): sound, lameness front limb, lameness hindlimb. Additionally, for each horse, the affected limb (AL) and degree of lameness (DL)...
Analysis of a radiographic technique for measurement of equine metacarpal bone shape. Accuracy and limitations of a radiographic technique were established for measurement of metacarpal bone shape in horses. A radiographic index (RI) has been used to measure changes in third metacarpal (Mc3) bone shape in response to training in young racehorses. The aim of these experiments was to determine the effects of positioning of the radiographic equipment on RI measurements from lateromedial radiographs of a left ex vivo metacarpus. Repeatability of the RI measurement in left lateromedial and right mediolateral view Mc3s were evaluated. The width of the dorsal cortex (DC), palmar corte...
Determination of hoof mass and centre of mass from morphological measurements. Determination of net joint moments and powers requires accurate measurements of mass and centre of mass (COM) for the limb segments. The objective of this research was to develop regression equations for calculating mass and COM of the hoof segment that are applicable over a wide range of hoof morphologies. Ninety-one hooves (mean +/- s.d. 0.99 +/- 0.50 kg) were weighed and the 3-dimensional COM determined using a mass balance technique. Ten morphological variables were measured and used as independent variables in linear regressions with dependent variables of mass and centre of mass. The reg...
Kinematic analysis of the symmetry of limb movements in lame trotting horses. This study was undertaken to describe the symmetry of movements of fore- and hindlimbs in horses suffering from various spontaneous lamenesses. Two groups of horses were studied: 13 clinically sound horses and 24 lame horses. Using a 3-dimensional (3-D) kinematic analysis system, movements of both sides of each horse were recorded simultaneously while trotting on a track. The differences in motion between left and right homologous joints of each horse were quantified using symmetry indices based on an intercorrelation method. Symmetry indices obtained for each lame horse were then compared wit...
Range of back movement at trot in horses without back pain. The aim of this study was to establish basic reference data for evaluating 3-dimensional movement of the equine back at the trot. In 22 mature horses without any clinical signs of back pain, the movement of the back was measured during trotting on a treadmill with a system for motion analysis. The position of the markers placed on the head, hooves, skin above the spinous processes of T5, T10, T16, L3 and on 2 of the sacral spines was recorded. The results of all movements were expressed in percent of the horse's height at its withers. At the trot, the maximum lateral movement at the head was 1...
Description of ciliary body anatomy and identification of sites for transscleral cyclophotocoagulation in the equine eye. To determine the most appropriate anatomical location for diode laser probe placement to accurately photoablate the equine ciliary body using a contact, transscleral approach. Methods: Original research. Methods: Forty-two freshly enucleated adult equine eyes were evaluated. The horizontal, medial vertical, central vertical, and lateral vertical lengths of the cornea were measured from limbus to limbus. Needles were inserted perpendicular to the sclera at specific distances posterior to the external limbus at the 1, 2, 4, 5, 6, 7, 8, 10, 11 and 12 o'clock positions. The per cent frequency that...
Evaluation of the EMG activity of the long back muscle during induced back movements at stance. In this study we investigated the activity of the main back muscle (Musculus longissimus) by surface electromyography (EMG) during induced extension and lateral flexion at stance. Measurements were taken of 15 horses (age 5-20 years, 450-700 kg bwt) without signs of back pain. Reflecting markers were placed on the head, spinous processes of T5, T12, T16, L3 and on 2 of the sacral bones. The surface EMG electrodes were situated on the Musculus longissimus on both sides of the dorsal spinous processes of T12, T16 and L3. In all horses and all movements (extension, lateral flexion to the left and...
Components of variation of surface hoof strain with time. The relative contribution of a number of random and fixed variables to variation in surface strain magnitudes on the hoof capsule was assessed for healthy feet under normal conditions. Principal strains were recorded in vivo from 5 rosette gauges glued around the circumference of the right forefeet of 4 horses on 4 occasions over a 9 month period. Recordings were made at every other trimming and reshoeing. During each session, gauges were positioned with a template for repeatability. Strains were recorded at the trot and canter (at consistent speeds), for straight motion and turns, and before ...
Phacofragmentation for morgagnian cataract in a horse. A 3-year-old Paint gelding was presented for sudden onset of cataract affecting the right eye. Ophthalmic examination revealed subtle to mild microphthalmia and a mature cataract affecting the right globe. The right eye was treated with an antibiotic-corticosteroid ophthalmic ointment and phacofragmentation was recommended. On re-examination 5 months later, resorption of the cortex of the right lens and a morgagnian cataract were evident. The nucleus was positioned ventronasally in the lens capsule. The right eye had light perception, and a menace response was present. Examination of the right...
Body centre of mass movement in the lame horse. The body centre of mass (BCM) is a key factor in the analysis of equine gait, as its position and movement determines the distribution and magnitude of loads on the limbs. Changes in the BCM movement are proposed to be important factors in the lameness management of horses. In this study, changes in the position and the 3-dimensional (3-D) movement of the BCM in horses with induced forelimb lameness were studied using a kinematic, segmental method. The kinematics of 30 markers representing 20 body segments were recorded in 12 horses while trotting (3.9 m/s) on a treadmill using a high speed vi...
Effects of heel and toe elevation upon the digital joint angles in the standing horse. Five sound mature horses, age 8-14 years, with toe angles 45.5-55.0 degrees were placed on a specially designed platform with only the left forelimb weightbearing, which allowed the successive production of 7 different conditions of foot orientation: neutral position (N), 5, 10, 15 degrees heel (H5, H10, H15) and toe (T5, T10, T15) elevation, performed according to 2 different sequences. For each condition, 2 lateromedial radiographs were taken to evaluate the metacarpophalangeal joint (MPJ) and both interphalangeal joint (PIPJ and DIPJ) angles, respectively. In addition, two-dimensional (2-D)...
Segmental in vivo vertebral kinematics at the walk, trot and canter: a preliminary study. Understanding the pathophysiology of equine back problems, for clinical evaluation, treatment or injury prevention, requires understanding of the normal 3-dimensional motion characteristics of the vertebral column. Recent studies have investigated regional vertebral kinematics; however, there are no reported measures of direct in vivo segmental vertebral kinematics in exercising horses. Relative movements between 2 adjacent vertebrae were recorded for 3 horses that were clinically sound and did not have a known history of a back problem. A transducer consisting of 2 fixtures and an array of li...
Quantification of hoof deformation using optical motion capture. Deformation of the hoof capsule occurs during stance phase as a result of loading by the distal phalanx. The objective of this study was to evaluate optical motion capture as a technique for measuring hoof deformation during locomotion, and to quantify the deformation of the dorsal wall during stance phase. The front left feet of 3 clinically sound horses were used for this study. The hoof wall was cleaned and 9 retroreflective markers were glued to the lateral and dorsal hoof wall, and shoe. Each horse was trotted in a straight line at constant speed while marker positions during stance phase...
Wedge-shaped conformation of the dorsolateral aspect of the third tarsal bone in the Thoroughbred racehorse is associated with development of slab fractures in this site. Anecdotal evidence suggested that many cases of third tarsal bone (T3) fracture encountered clinically were associated with an abnormal shape to this bone. The radiographs of 10 normal horses and 10 horses affected with slab fracture of T3 were therefore examined to ascertain if any pre-existent radiological abnormality was present in cases of fracture. Measurement of the maximum and minimum width between the proximal and distal articular surfaces of the dorsolateral aspect of this bone was carried out on a standardised dorso-50 degrees medial-palmarolateral radiographic projection of the tars...
Effect of romifidine on gastrointestinal motility, assessed by transrectal ultrasonography. A technique of transrectal ultrasonography was developed to investigate the effects of romifidine 80 and 120 microg/kg bwt on intestinal motility in the horse. Motility of the small intestine, caecum and left ventral colon were assessed following injection of romifidine and a saline control, using a blinded, cross-over study design in 6 horses. Measurements were taken at 15, 30, 60, 120, 180 and 240 min after drug administration. There was a slight nonsignificant decrease in motility in the control group over the 4 h study period. Both doses of romifidine produced a marked decrease in gastroin...
Factors influencing blood flow in the equine digit and their effect on uptake of 99m technetium methylene diphosphonate into bone. It was hypothesised that exercise may promote perfusion of the distal part of the limbs and enhance uptake of radiopharmaceutical into bone, but bandaging and lameness would have no effect. Two hundred and two horses undergoing routine nuclear scintigraphic examination for assessment of lameness or poor performance between November 1998 and November 1999 were assigned randomly to one of 4 groups: no bandages and no exercise (NB/NE); bandages and no exercise (B/NE); no bandages and exercise (NB/E); bandages and exercise (B/E). In the bandage groups, the distal forelimbs were bandaged for at lea...
Application of a constant blood withdrawal method in equine exercise physiology studies. The aim of the present study was to test a constant blood withdrawal method (CBWM) to collect blood samples from horses during treadmill exercise. CBWM was performed in 4 Standardbreds and 5 Haflinger horses. A peristaltic pump was used to control blood aspiration from an i.v. catheter via an extension line. Blood was collected using an automatic fractions collector, with a constant delay time between the drawing of blood and sample collection. Blood withdrawal using CBWM was made during a treadmill standardised exercise test (SET). A blood flow of 12 m/min was used and samples collected every...
Measurement of serum amyloid A in the neonatal foal using a latex agglutination immunoturbidimetric assay: determination of the normal range, variation with age and response to disease. This paper describes the use of a latex agglutination assay to measure serum amyloid A (SAA) in the neonatal foal. The normal range and response to clinical disease was determined. This retrospective study evaluated SAA concentrations over the first 3 days postpartum of 226 Thoroughbred foals judged to be clinically healthy. The normal range for each day was determined; levels were found to be significantly highest on Day 2 (Day 1 vs. Day 2 P<0.0001). The 95th percentile for Days 1-3 was 27.1 mg/l. Clinical records of 133 foals, presented as first or second opinion cases, were evaluated. Fo...
Flowmetric comparison of respiratory inductance plethysmography and pneumotachography in horses. Respiratory inductance plethysmographic (RIP) and pneumotachographic (Pn) flows were compared dynamically in horses with bronchoconstriction. On a breath-by-breath basis, RIP was normalized to inspiratory volume from Pn, and peak [peak of subtracted final exhalation waveform (SFE(max))] and selected area [integral of subtracted final waveform during first 25% of exhaled volume (SFE(int))] differences between RIP and Pn flows during early expiration were measured in three settings: 1) healthy horses (n = 8) undergoing histamine bronchoprovocation; 2) horses with naturally occurring lower airway...
