Topic:Adult Horses
Adult horses encompass a category of equines that have reached maturity, typically considered to be around five years of age and older. This stage of life is characterized by full physical development and the potential for peak performance in various activities such as riding, racing, and work. Adult horses require specific nutritional, health, and management practices to maintain optimal condition and performance. The study of adult horses covers a range of topics, including physiology, behavior, and the impact of environmental factors on their well-being. This page compiles peer-reviewed research studies and scholarly articles that explore the physiology, health management, and performance aspects of adult horses.
Glucocorticoids and laminitis in the horse. The administration of exogenously administered GCs and syndromes associated with GC excess are both attended by increased risk for the development of laminitis in adult horses. However, there exists substantial controversy as to whether excess GCs cause laminitis de novo. If true, the pathogenesis of laminitis arising from the effects of GC excess is probably different from that associated with diseases of the gastrointestinal tract and endotoxemia. Although a satisfactory explanation for the development of laminitis as a consequence of GC action is currently lacking, numerous possible and pla...
Helminths in horses: use of selective treatment for the control of strongyles. The current level of anthelmintic resistance in the horse-breeding industry is extremely high and therefore more emphasis is being placed on studies that focus on the judicious use of anthelmintic products. The aims of the study were to: 1) establish if there is variation in the egg excretion pattern of strongyles between the different age classes of Thoroughbred horses in the Western Cape Province (WCP), 2) test if a selective treatment approach successfully reduces the number of anthelmintic treatments and maintains acceptably low helminth burdens in adult Thoroughbred horses, and 3) evaluat...
Repeated intraarticular injections of triamcinolone acetonide alter cartilage matrix metabolism measured by biomarkers in synovial fluid. Although intraarticular (IA) corticosteroids are frequently used to treat joint disease, the effects of their repeated use on articular cartilage remains controversial. The aim of our study was to determine the effects of a clinically recommended dose of IA triamcinolone acetonide (TA), on synovial fluid (SF) biomarkers of cartilage metabolism. Ten adult horses, free of osteoarthritis (OA) in their radiocarpal joints, were studied. One radiocarpal joint of each horse was randomly chosen for treatment and the contralateral anatomically paired joint acted as the control. Aseptic arthrocentesis w...
Pharmacokinetic-pharmacodynamic relationships and dose response to meloxicam in horses with induced arthritis in the right carpal joint. To determine pharmacokinetic-pharmacodynamic (PK-PD) relationships and dose effects for meloxicam in horses and to propose a suitable dosage for use in clinical studies. Methods: 6 adult horses. Methods: The study was conducted by use of a randomized, Latin-square design. Arthritis was induced in the right carpal joint of each horse by administration of Freund's complete adjuvant. Various dosages of meloxicam (0, 0.25, 0.5, 1.0, and 2.0 mg/kg, IV) were then administered. Validated endpoints including stride length and overall clinical lameness score (scale of 0 to 20) were used to assess the e...
Effects of phenylbutazone, indomethacin, prostaglandin E2, butyrate, and glutamine on restitution of oxidant-injured right dorsal colon of horses in vitro. To study the effects of phenylbutazone, indomethacin, prostaglandin E2 (PGE2), glutamine, and butyrate on restitution of oxidant-injured right dorsal colon of horses in vitro. Methods: Right dorsal colon from 9 adult horses euthanatized for reasons other than gastrointestinal tract disease. Methods: Mucosal segments from the right dorsal colon were injured via exposure to HOCl and incubated in Ussing chambers in solutions containing phenylbutazone, indomethacin, indomethacin and PGE2, glutamine, and butyrate. Transepithelial resistance and mucosal permeability to mannitol were measured, and al...
Onchocerca cervicalis in horses from southern Brazil. The objective of this study was to determine the occurrence of Onchocerca cervicalis in 1200 adult horses from rural areas of Rio Grande do Sul, Brazil. Umbilical skin specimens measuring 2 x 2 cm were minced, suspended in 10 ml of distilled water and incubated at room temperature overnight. The liquid volume was centrifuged and the sediment was screened for microfilariae. The ligamentum nuchae were totally removed, preserved in ice and dissected for the detection of adult forms of Onchocerca cervicalis. Microfilariae of Onchocerca cervicalis were detected in midventral skin biopsy samples in ...
Rhodococcus equi-infected macrophages are recognized and killed by CD8+ T lymphocytes in a major histocompatibility complex class I-unrestricted fashion. The goal of this research was to examine the role of cytotoxic T lymphocytes (CTL) in the control of Rhodococcus equi and specifically to determine if R. equi-specific CD8+ CTL occurred in the blood of immune horses. Equine peripheral blood mononuclear cells stimulated with antigen-presenting cells either infected with R. equi or exposed to soluble R. equi antigen lysed R. equi-infected target cells. Lysis was decreased to background by depletion of either CD2+ or CD3+ cells, indicating that the effector cell had a T-lymphocyte, but not NK cell, phenotype. Stimulation induced an increased perc...
Biomechanical and energetic determinants of the walk-trot transition in horses. We studied nine adult horses spanning an eightfold range in body mass (M(b)) (90-720 kg) and a twofold range in leg length (L) (0.7-1.4 m). We measured the horses' walk-trot transition speeds using step-wise speed increments as they locomoted on a motorized treadmill. We then measured their rates of oxygen consumption over a wide range of walking and trotting speeds. We interpreted the transition speed results using a simple inverted-pendulum model of walking in which gravity provides the centripetal force necessary to keep the leg in contact with the ground. By studying a large size range of ...
Cefotaxime kinetics in plasma and synovial fluid following intravenous administration in horses. Cefotaxime powder was diluted with sterile water to a concentration of 100 mg/mL. The volume of solution was adjusted for each experimental horse to provide a total dose of 15, 20, and 25 mg/kg and was administered by infusion through a jugular vein catheter over a 10-min period. All three doses were administered to each of the six experimental horses at three different times. Cefotaxime concentrations in plasma and synovial fluid samples were measured by high-performance liquid chromatography (HPLC). Standard compartmental analysis techniques and the WinSAAM modeling program were used to dete...
Fatal yew (Taxus sp) poisoning in Willamette Valley, Oregon, horses. Despite the well-founded reputation of plants of the genus Taxus as being amongst the most toxic plants for domestic livestock in the US, there are surprisingly few published case reports of yew poisoning in horses. This report documents 2 acute fatalities in horses in the central Willamette Valley, OR associated with the consumption of Taxus sp. The predominant features of the intoxication were peracute death, with no signs of struggling or convulsions, in otherwise fit and well managed adult horses. The most significant gross necropsy findings were limited to pulmonary congestion and hemorrh...
Response of induced bone defects in horses to collagen matrix containing the human parathyroid hormone gene. To determine whether human parathyroid hormone (hPTH) gene in collagen matrix could safely promote bone formation in diaphyseal or subchondral bones of horses. Methods: 8 clinically normal adult horses. Methods: Amount, rate, and quality of bone healing for 13 weeks were determined by use of radiography, quantitative computed tomography, and histomorphometric analysis. Diaphyseal cortex and subchondral bone defects of metacarpi were filled with hPTH(1-34) gene-activated matrix (GAM) or remained untreated. Joints were assessed on the basis of circumference, synovial fluid analysis, pain on flex...
Scintigraphic appearance of the dorsal cortex of the third metacarpus and third metatarsus in the horse. The lack of "standard uptake pattern" to refer to when interpreting scintigraphic images poses a problem to anyone working with skeletal scintigraphy. An article written by Koblik et al. stated that in the normal scintigraphic image of older horses, the dorsal cortex of the metacarpus and metatarsus is not identifiable, whereas it can be identified in younger horses. In this retrospective study we evaluated the association between the age of a horse and visibility of the dorsal cortex of the metacarpus and metatarsus. We found that dorsal cortical uptake can be seen in the normal adult horse. ...
Comparison of 4 blood storage methods in a protocol for equine pre-operative autologous donation. To compare viability of equine whole blood stored by 4 different methods, and to establish optimal storage protocols for an equine autologous blood donation program. Methods: In vitro study of stored equine whole blood. Animals- Six healthy adult horses. Methods: Blood from each horse was collected into 4 different containers: glass bottles containing acid-citrate-dextrose solution (ACD), plastic bags containing ACD, citrate-phosphate-dextrose (CPD), and CPD with supplemental adenine (CPDA-1). Blood was stored for 5 weeks and sampled at 2-day intervals. Standard hematologic and biochemical var...
Evaluation of arthrocentesis site bacterial flora before and after 4 methods of preparation in horses with and without evidence of skin contamination. To evaluate the effectiveness of four methods of povidone-iodine preparation on skin bacterial flora of arthrocentesis sites, in horses, with and without evidence of skin contamination. Methods: Prospective randomized study. Methods: Twenty-four adult horses. Methods: Horses were assigned to either the clean or contaminated group based on housing environment and visual evidence of contamination. Using a moist sterile swab, microbial culture samples were obtained from the skin over the distal interphalangeal joints immediately before and after preparation. Each site was aseptically prepared wit...
Intracranial elastance in isoflurane-anesthetized horses. To determine whether high intracranial pressure (ICP) during spontaneous ventilation (SV) in anesthetized horses coincides with an increase in intracranial elastance (ie, change in ICP per unit change of intracranial volume). Methods: 6 adult horses. Methods: Anesthesia was induced and maintained in each horse for 5 hours with isoflurane at a constant dose equal to 1.2 times the minimum alveolar concentration. Direct ICP measurements were obtained by use of a strain gauge transducer inserted in the subarachnoid space, and arterial blood pressure was measured from a carotid artery. Physiologic ...
Risk factors associated with fecal Salmonella shedding among hospitalized horses with signs of gastrointestinal tract disease. To estimate prevalence of and identify risk factors for fecal Salmonella shedding among hospitalized horses with signs of gastrointestinal tract disease. Methods: Cross-sectional study. Methods: 465 hospitalized horses with gastrointestinal tract disease. Methods: Horses were classified as positive or negative for fecal Salmonella shedding during hospitalization by means of standard aerobic bacteriologic methods. The relationship between investigated exposure factors and fecal Salmonella shedding was examined by means of logistic regression. Results: The overall prevalence of fecal Salmonella ...
Investigation of the facilitation of the nociceptive withdrawal reflex evoked by repeated transcutaneous electrical stimulations as a measure of temporal summation in conscious horses. To investigate whether facilitation of the nociceptive withdrawal reflex (NWR) can be evoked and quantified as a measure of temporal summation from the distal aspect of the left forelimb and hind limb in standing nonsedated horses via repeated stimulations of various subthreshold intensities and frequencies. Methods: 10 adult horses. Methods: Surface electromyographic activity evoked by stimulation of the digital palmar and plantar nerves was recorded from the common digital extensor and cranial tibial muscles. For each horse, the NWR threshold intensity to a single stimulus was determined for...
Compensated overexpression of procollagens alpha 1(I) and alpha 1(III) following perilla mint ketone-induced acute pulmonary damage in horses. Interstitial lung disease with chronic fibrosis is a frequent cause of reduced performance in horses. The aim of this study was to establish a model of acute alveolar damage and interstitial lung disease in horses that could be used to monitor the histopathological lesions and changes in expression levels of genes relevant to pulmonary fibrosis. Six adult horses were given a single intravenous injection (6 mg per kg body weight) of perilla mint ketone (PMK). Transthoracic lung biopsy samples (1 x 0.2 x 0.2 cm) were collected before and after (days 1, 4, 8, 11, 15, 18, 22, 25 and 29) the admini...
Idiopathic gastroesophageal reflux disease in an adult horse. Chronic gastroesophageal reflux disease was diagnosed in a 22-year-old female Tennessee Walking Horse that had signs of bruxism and ptyalism. Esophageal ulceration was detected via endoscopy. Compared with the damage to the proximal portions of the esophagus, the severity of the ulceration increased toward the gastroesophageal junction. Esophageal ulceration attributable to chronic gastric acid reflux is usually secondary to pyloric outflow obstruction in horses. In the horse of this report, there was no evidence of either a chronic pyloric or duodenal obstruction that could have resulted in e...
Comparison of the navicular region of newborn foals and adult horses by magnetic resonance imaging. Magnetic resonance imaging (MRI) was tested for evaluation of the soft tissue structures of the equine digit in 16 limbs, derived from three adult warmblood horses and two newborn warmblood foals. The following measuring sequences were used in sagittal, transversal and coronal planes: spin echo, gradient echo, inversion recovery. The images were made with a 1.5 Tesla Siemens scanner in a CP-Helmholtz circular coil. To compare the visualization of the same tissue structures in adult and in newborn cases the limbs were imaged with the routinely used MRI sequences that are used for mature tissues...
Objective determination of pelvic movement during hind limb lameness by use of a signal decomposition method and pelvic height differences. To evaluate pelvic movement over a large number of strides in sound horses and in horses with induced hind limb lameness by applying methods to the pelvis that have been described for evaluating vertical head movement in horses with induced forelimb lameness. Methods: 17 adult horses. Methods: Horses were filmed while trotting on a treadmill before and after induction of transient mild and moderate hind limb lamenesses. Vertical pelvic movement was measured by a signal decomposition method. The vertical pelvic signal was decomposed into a periodic component (A1) that occurred at half the strid...
Phenytoin sodium as a treatment for ventricular dysrhythmia in horses. Five adult horses with ventricular extra systoles (VES) and 2 with ventricular tachycardia (VT) refractory to treatment with rest, anti-inflammatory drugs, lidocaine, or procainamide were treated with phenytoin sodium p.o. q12h. The starting dosage of phenytoin was 20 or 22 mg/kg body weight (BW) q12h, and the maintenance dosage varied from 8 to 17 mg/kg BW q12h. The mean +/- standard deviation therapeutic blood concentration of total phenytoin was 8.8 +/- 2.1 mg/L, and the mean concentration of free phenytoin of 2.5 +/- 0.5 mg/L was relatively constant at a range of 24 to 29% of the total phe...
Disposition of flunixin meglumine injectable preparation administered orally to healthy horses. An injectable preparation of flunixin meglumine was administered orally and intravenously at a dose of 1.1 mg/kg to six healthy adult horses in a cross-over design. Flunixin meglumine was detected in plasma within 15 min of administration and peak plasma concentrations were observed 45-60 min after oral administration. Mean bioavailability of the oral drug was 71.9 +/- 26.0%, with an absorption half-life of 0.76 h. The apparent elimination half-life after oral administration was 2.4 h. The injectable preparation of flunixin meglumine is suitable for oral administration to horses.
Effect of carboxymethylcellulose and hyaluronate solutions on jejunal healing in horses. To compare a double-layer inverting anastomosis with a single-layer appositional anastomosis, coated with either 1% sodium carboxymethylcellulose (SCMC) or 0.4% sodium hyaluronate (HA) solutions, in the small intestine of horses with respect to anastomotic healing and adhesion formation. Methods: 18 adult horses. Methods: Midline celiotomy and end-to-end jejunal anastomoses were performed. In control group horses (n = 6), a double-layer inverting anastomosis coated with sterile lactated Ringer's solution was performed. In treatment group horses, a single-layer appositional anastomosis was perf...
Evaluation of a sensor-based system of motion analysis for detection and quantification of forelimb and hind limb lameness in horses. To compare a sensor-based accelerometer-gyroscopic (A-G) system with a video-based motion analysis system (VMAS) technique for detection and quantification of lameness in horses. Methods: 8 adult horses. Methods: 2 horses were evaluated once, 2 had navicular disease and were evaluated before and after nerve blocks, and 4 had 2 levels of shoe-induced lameness, alternatively, in each of 4 limbs. Horses were instrumented with an accelerometer transducer on the head and pelvis, a gyroscopic transducer on the right forelimb and hind feet, and a receiver-transmitter. Signals from the A-G system were...
The effect of enrofloxacin on cell proliferation and proteoglycans in horse tendon cells. Fluoroquinolone antibiotics have been used widely in humans and domestic animals, including horses, because of their broad-spectrum bactericidal activity, and relative safety. The use of fluoroquinolones, however, is not without risk. Tendonitis and spontaneous tendon rupture have been reported in people during or following therapy with fluoroquinolones. We have studied the effects of enrofloxacin, a fluoroquinolone antibiotic used commonly in domestic animals, on tendon cell cultures established from equine superficial digital flexor tendons. Effects on cell proliferation and morphology were ...
Recombinant canarypoxvirus vaccine carrying the prM/E genes of West Nile virus protects horses against a West Nile virus-mosquito challenge. An ALVAC (canarypoxvirus)-based recombinant (vCP2017) expressing the prM and E genes derived from a 1999 New York isolate of West Nile virus (WNV) was constructed and assessed for its protective efficacy in horses in two different experiments. In the first trial, a dose titration study was conducted to evaluate both serum neutralising antibody responses to WNV and duration of immunity. In the second trial the onset of protection was determined. Twenty-eight adult horses received two doses of vCP2017 administered intramuscularly at 5-week intervals and sixteen horses comprised age-matched non-v...
The bioavailability and pharmacokinetics of glucosamine hydrochloride and chondroitin sulfate after oral and intravenous single dose administration in the horse. The purpose of this study was to determine if glucosamine (GL) hydrochloride (FCHG49) and low molecular weight (LMW) chondroitin sulfate (CS) (TRH122) are absorbed after oral administration to horses. The bioavailability of LMWCS was evaluated by quantifying the total disaccharides found in the plasma following chondroitinase ABC digestion. Methods: Two separate studies were conducted. In study 1, ten adult horses received the following four treatments in a randomized crossover fashion: (1) i.v. LMWCS (3 g of 8 kDa), (2) p.o. LMWCS (3 g of 8 kDa), (3) i.v. LMWCS (3 g of 16.9 kDa) and (4) p.o. ...