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.
Use of Polyamide (Nylon) Cable Ties for Vascular Ligation of Healthy Equine Jejunal Mesentery. Jejunal vascular ligation is an essential step in performing jejunojejunostomy. Hand sewn ligation is typically used and can increase operative time with long sections of bowel to be removed. Nylon cable ties (NCT) have been used for vascular ligation in horses but are yet to be investigated for application on the mesenteric vasculature of the gastrointestinal tract. Our objective was to evaluate the efficacy and short-term safety of NCT jejunal mesenteric vessel ligation in healthy horses. Eight healthy adult horses underwent midline celiotomy. A segment of jejunal mesentery was identified (â...
Comparative Trial of Continuous Flow Enteral and Intravenous Fluid Therapy in Horses. Continuous flow enteral fluid therapy with isotonic and hypotonic enteral electrolyte solutions are as safe and effective as intravenous fluid therapy. The aim of this study was to carry out a comparative assessment between continuous flow enteral and intravenous (IV) fluid therapy in adult experimentally dehydrated horses. Six experimentally dehydrated adult mares were used in a study carried out in a 6 × 3 crossover design, which each animal received three different treatments (isotonic enteral fluid therapy-EsISO, hypotonic enteral fluid therapy-EsHYPO and intravenous fluid therapy with La...
Electrical impedance tomography to measure lung ventilation distribution in healthy horses and horses with left-sided cardiac volume overload. Left-sided cardiac volume overload (LCVO) can cause fluid accumulation in lung tissue changing the distribution of ventilation, which can be evaluated by electrical impedance tomography (EIT). Objective: To describe and compare EIT variables in horses with naturally occurring compensated and decompensated LCVO and compare them to a healthy cohort. Methods: Fourteen adult horses, including university teaching horses and clinical cases (healthy: 8; LCVO: 4 compensated, 2 decompensated). Methods: In this prospective cohort study, EIT was used in standing, unsedated horses and analyzed for convent...
Seasonal Variation in the Faecal Microbiota of Mature Adult Horses Maintained on Pasture in New Zealand. Seasonal variation in the faecal microbiota of forage-fed horses was investigated over a 12-month period to determine whether the bacterial diversity fluctuated over time. Horses ( = 10) were maintained on pasture for one year, with hay supplemented from June to October. At monthly intervals, data were recorded on pasture availability and climate (collected continuously and averaged on monthly basis), pasture and hay samples were collected for nutrient analysis, and faecal samples were collected from all horses to investigate the diversity of faecal microbiota using next-generation sequencing ...
Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution in Healthy Standing Horses. Bioreactance is the continuous analysis of transthoracic voltage variation in response to an applied high frequency transthoracic current and was recently introduced for non-invasive cardiac output measurement (NICOM). We evaluated NICOM compared to thermodilution (TD) in adult horses. Six healthy horses were used for this prospective, blinded, experimental study. Cardiac output (CO) measurements were performed simultaneously using TD and the bioreactance method. Different cardiac output scenarios were established using xylazine (0.5 mg/kg IV) and dobutamine (1.5-3 mcg/kg/min). Statistical ana...
Assessment of qualitative and quantitative parameters of healthy thyroid gland in adult horses by magnetic resonance imaging. In humans and pets, magnetic resonance imaging (MRI) provides important adjunctive anatomic information about the thyroid and its adjacent structures. To the best of our knowledge, however, no studies have been reported regarding the use of MRI for thyroid evaluation in horses. The aim of this study was to obtain qualitative and quantitative parameters of healthy thyroid gland in adult horses by MRI. Eleven horses were submitted to thyroid MRI evaluation. The healthy thyroid of these animals was ensured by normal examinations performed before (free thyroxine and ultrasound) and after (cytology...
Gentamicin-induced sensorineural auditory loss in healthy adult horses. Irreversible sensorineural auditory loss has been reported in humans treated with aminoglycosides but not in horses. Objective: Investigate if auditory loss occurs in horses treated using the recommended IV daily dosage of gentamicin for 7 consecutive days. Methods: Ten healthy adult horses (7-15 years; females and males, 5 each). Methods: Prospective study. Physical and neurological examinations and renal function tests were performed. Gentamicin sulfate was administered at a dosage of 6.6 mg/kg via the jugular vein on alternating sides for 7 days. Gentamicin peak and trough concentratio...
Effects of an articular cartilage lubrication with a viscosupplement in vitro and in vivo following osteochondral fractures in horses. To assess whether the combination of hyaluronan, sodium chondroitin sulfate, and -acetyl-d-glucosamine (HCSG) lubricates articular cartilage in vitro and modulates joint lubrication in vivo. Methods: 16 healthy adult horses. Methods: The effects of HCSG injections on SF lubricant properties and joint health, immediately after injury and 2 weeks later, were analyzed by use an equine osteochondral fracture model of post-traumatic osteoarthritis (OA). Middle carpal joints of adult horses were randomly assigned to 1 of 4 surgical treatment groups as follows: normal nonsurgical group (n = 8), norma...
Immune response of adult horses, pregnant mares and foals to an experimental vaccine with recombinant EMA-2 protein of Theileria equi. Equine theileriosis, caused by the Theileria equi protozoan, is a disease of worldwide importance. T. equi expresses surface proteins, of which the EMA-2 protein is a promising antigen for vaccine use. The aim of this study was to evaluate the immune response of adult horses, pregnant mares, and foals to an experimental EMA-2 protein of recombinant T. equi vaccine. A total of 46 horses were used in this study for vaccine trials and challenges. Twelve geldings, 14 pregnant mares, and 14 foals were divided into vaccinated and control groups. Total serum specific anti-rEMA-2 IgG, IgG subclasses, ...
Investigation of the Bi-Weekly Administration of Diclazuril on the Antibody Kinetics to Sarcocystis Neurona in Healthy Horses. The aim of this study was to determine if bi-weekly administration of diclazuril at half the label dose would reduce seroprevalence and magnitude of titers to S. neurona in healthy horses naturally exposed to the apicomplexan protozoal parasite. 12 healthy adult horses were moved from a low-risk exposure to a farm with high exposure rate to S. neurona in their horse population. The horses were randomly assigned to either a treatment or a control group. Treatment consisted in the administration of half the label dose (0.5 mg/kg) of diclazuril (Protazil) pelleted top dress twice weekly (every 3-...
Comparison of one-layer Utrecht pattern with two-layer (simple continuous/Cushing) pattern for jejunojejunostomy in healthy horses in vivo. To compare end-to-end jejunal anastomoses with a one-layer (Utrecht) and two-layer (simple continuous/Cushing) patterns. Methods: Experimental study. Methods: Eight healthy adult horses. Methods: Jejunal end-to-end anastomoses were performed in randomly assigned one-layer or two-layer patterns. Horses were recovered from surgery and monitored for complications. At 14 days, the opposite pattern was performed (cross-over design) prior to euthanasia. Duration of closures was compared between patterns. Serosal width was measured before harvesting anastomotic sites from the first procedure. Lumin...
Treatment of temporohyoid osteoarthropathy in horses with a basihyoid-ceratohyoid disarticulation technique: 6 cases (2018-2019). To describe a technique for basihyoid-ceratohyoid disarticulation (BCD) in standing sedated horses affected by temporohyoid osteoarthropathy (THO) and report outcomes for horses that underwent the procedure. Methods: 6 client-owned horses. Methods: Electronic medical records of a veterinary teaching hospital were searched to identify horses that underwent BCD for treatment of THO from 2018 to 2019. Signalment, clinical data, use of the horse, and complications were recorded. Follow-up data obtained by telephone interview with owners included the clinical outcome and time to improvement after s...
Postprandial insulin responses to various feedstuffs differ in insulin dysregulated horses compared with non-insulin dysregulated controls. Controlling postprandial hyperinsulinaemia is important in insulin dysregulated (ID) horses to reduce the risk of laminitis. Objective: To evaluate postprandial insulin responses of ID versus non-insulin dysregulated (NID) horses to feedstuffs varying in nonstructural carbohydrate (NSC) and crude protein (CP). Methods: Randomised crossover. Methods: Eighteen adult mixed-breed horses (13.3 ± 2.2 years; 621 ± 78.8 kg) were individually fed [~1 g/kg body weight (BW)] specific feedstuffs within two crossover studies. Eight ID and eight NID were used in Study A, and 11 ID and 5 NID in Stud...
Equine inflammatory response to abdominal surgery in the absence of gastrointestinal disease. To investigate the, equine inflammatory response to ventral midline celiotomy in the absence of gastrointestinal disease in horses of varying body condition scores primarily using serial measurements of serum amyloid A (SAA). Methods: Experimental clinical study. Methods: University teaching hospital. Methods: Ten adult light breed horses free of any clinical disease, 5 with body condition score (BCS) 3-4/9 and 5 with BCS 7-8/9. Methods: Horses had a ventral midline celiotomy performed under general anesthesia, including manual decompression of the small intestine. SAA, semiquantitative fibrin...
Microfracture Augmentation With Trypsin Pretreatment and Growth Factor-Functionalized Self-assembling Peptide Hydrogel Scaffold in an Equine Model. Microfracture augmentation can be a cost-effective single-step alternative to current cartilage repair techniques. Trypsin pretreatment combined with a growth factor-functionalized self-assembling KLD hydrogel ("functionalized hydrogel") has been shown to improve overall cartilage repair and integration to surrounding tissue in small animal models of osteochondral defects. Microfracture combined with trypsin treatment and a functionalized hydrogel will improve reparative tissue quality and integration as compared with microfracture alone in an equine model. Controlled laboratory study. Bilater...
Intratendinous Fibroma of the Superficial Digital Flexor Tendon within the Carpal Sheath of a Horse. A 20-year-old British Warmblood gelding was presented for a progressively worsening right forelimb lameness which developed following an intense dressage training session. Initial ultrasound examination revealed a triangular, intrathecal, hypoechoic region within the superficial digital flexor tendon (SDFT) in the proximal, palmar carpal region distal to the accessory carpal bone (ACB), extending 7cm distally into the proximal metacarpal region. No significant improvement in clinical presentation was observed following an eight-week rehabilitation programme. Repeat ultrasound examination revea...
Uncoupling Protein-1 (UCP1) in the Adult Horse: Correlations with Body Weight, Rectal Temperature and Lipid Profile. This study aimed to evaluate the possible relationship among UCP1, body weight, rectal temperature and lipid profile in the horse. Thirty clinically healthy Italian Saddle geldings (6-10 years old) were enrolled after the informed owners' consent. All horses were blood sampled and their body weight and rectal temperatures were recorded. On the sera obtained after blood centrifugation the concentration of UCP1, total lipids, phospholipids, non-esterified fatty acids (NEFAs), triglycerides, total cholesterol, high density lipoproteins (HDLs), low density lipoproteins (LDLs) and very low density ...
The effect of xylazine on intracranial pressure in anesthetized and standing horses. To determine the effect of xylazine on intracranial pressure (ICP) in standing compared to isoflurane-anesthetized horses. Methods: Prospective, crossover study design. Methods: University Teaching Hospital. Methods: Six adult horses donated to the University. Horses were determined to be healthy via physical examination, complete blood count, and neurological evaluation. Methods: Horses were anesthetized, maintained on isoflurane in oxygen in left lateral recumbency, and ventilated to normocapnia. Horses were instrumented for intraparenchymal measurement of ICP, invasive blood pressure, pulse...
Recovery after General Anaesthesia in Adult Horses: A Structured Summary of the Literature. Recovery remains the most dangerous phase of general anaesthesia in horses. The objective of this publication was to perform a structured literature review including levels of evidence (LoE) of each study with the keywords "recovery anaesthesia horse", entered at once, in the search browsers PubMed and Web of Science. The two authors independently evaluated each candidate article. A final list with 444 articles was obtained on 5 April 2021, classified as: 41 "narrative reviews/expert opinions", 16 "retrospective outcome studies", 5 "surveys", 59 "premedication/sedation and induction drugs", 27...
A bronchopulmonary artery fistula in a horse. A 24-year-old, Thoroughbred gelding presented with difficulty breathing for a few days and intermittent nose bleeding before dying. At necropsy, the bronchoesophageal artery and the bronchial artery that flowed into the left anterior lobe were tortuous and dilated, and it was found that dilated tortuous branches of the bronchial artery ran over the dorsal and ventral surfaces of the left anterior lobe. Histopathologically, an anastomosis between a muscular artery and an elastic artery were demonstrated, which were identified as bronchial and pulmonary arteries, respectively. Based on the gross...
Blood lactate concentrations and heart rates of Colombian Paso horses during a field exercise test. Information on performance indices in Paso horses is scarce. Field exercise tests are necessary to recreate the exertion that occurs during training and competition. To describe blood lactate concentrations and heart rates of untrained Colombian Paso horses (CPHs) in response to a field exercise test. A 30-minutes-long standardized field exercise test was carried out on 11 untrained adult CPHs of both sexes. Blood lactate concentration (BLConc) and heart rate (HR) were measured before, during each step of the test, and at recovery. The BLConc and HR were used to calculate the HR at which a BLC...
Pharmacokinetics of mycophenolate mofetil following single-dose intravenous and single- and multiple-dose oral administration and clinicopathologic effects of mycophenolate mofetil following long-term oral administration in healthy horses. To characterize the pharmacokinetics of mycophenolate mofetil (MMF) following single-dose IV or PO administration, characterize the pharmacokinetics of MMF following long-term PO administration, and describe the clinicopathologic effects of long-term MMF administration in horses. Methods: 12 healthy adult horses. Methods: In phase 1, 6 horses received a single IV (2.5 mg/kg) or PO (5 mg/kg) dose of MMF in a randomized balanced crossover assessment (≥ 2-week interval between administrations). In phase 2, 6 other horses received MMF for 60 days (5 mg/kg, PO, q 24 h for 30 days and then 5 mg/kg...
Evaluation of the in vitro effects of local anesthetics on equine chondrocytes and fibroblast-like synoviocytes. To investigate the in vitro effects of clinically relevant concentrations of the local anesthetics (LAs) bupivacaine, lidocaine, lidocaine with preservative (LP), mepivacaine, and ropivacaine on equine chondrocyte and fibroblast-like synoviocyte (FLS) viability. Methods: Chondrocytes and FLSs of the metacarpophalangeal joints of 4 healthy adult horses. Methods: Viability of chondrocytes and FLSs was determined with 3 assays: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH), and trypan blue (TB) exclusion (only FLS). Viability was assessed after 30...
Forage Characteristics and Grazing Preference of Cover Crops in Equine Pasture Systems. Cover crops are commonly used to provide environmental benefits and can extend the grazing season, but have not been explored in horse pastures. The objectives of this research were to evaluate forage mass, forage nutrient composition, and preference of annual ryegrass, winter rye, berseem clover, purple top turnip, and daikon radish under horse grazing. Cover crops were seeded in monoculture and mixtures in August 2018 and 2019 as a randomized complete block with four replicates and grazed by four adult horses. Prior to grazing, forages were sampled to determine herbage and root mass and nutr...
Extracranial guiding structures for navigation to specific topographical sectors of the equine neopallium: an anatomical investigation performing three-dimensional distance measurements in adult warm-blooded horses. This basically anatomical study focuses on two items; firstly, the establishment of a system for the cartographic subdivision of the neopallium; secondly, the topographical correlation of extracranial landmarks and intracranial sites on the neopallium. Methods: The surface of the neopallium was subdivided into 15 sectors with reference to a newly introduced pattern of Primary Sulci. The topographical link between extracranial landmarks and certain intracranial sites (i.e. neopallium sectors) was elaborated by using a simple stereotactic device and a computer-assisted measurement device. Measur...
Apparent digestibility, fecal particle size, and mean retention time of reduced lignin alfalfa hay fed to horses. Reduced lignin alfalfa (Medicago sativa L.) has the potential to provide a higher-quality forage source for livestock by improving forage digestibility. This study was conducted to evaluate apparent digestibility when feeding reduced lignin and nonreduced lignin alfalfa hay to adult horses, and to examine mean fecal particle size (MFPS) and mean retention time (MRT) between alfalfa forage types. In 2017, reduced lignin ("54HVX41") and nonreduced lignin ("WL355.RR") alfalfa hay was harvested in Minnesota at the late-bud stage. Alfalfa hays were similar in crude protein (CP; 199 g/kg), neutral d...
Rein Tension Signals Elicit Different Behavioral Responses When Comparing Bitted Bridle and Halter. When a rider maintains contact on the reins, rein tension will vary continuously in synchronicity with the horse's gait and stride. This continuous variation makes it difficult to isolate the rein tension variations that represent a rein tension signal, complicating interpretation of rein tension data from the perspective of horse-rider interaction. This study investigated (1) the characteristics of a rein tension signal and (2) horse response to a rein tension signal for backing, comparing pressure applied by a bit (bridle), or by a noseband (halter). Twenty Warmblood horses (10 young, 10 adu...
Risk factors for laminitis and nonsurvival in acute colitis: Retrospective study of 85 hospitalized horses (2011-2019). Acute colitis is a serious cause of morbidity and death in horses. Recent studies have compared clinical features of coronavirus and salmonellosis, but no study has compared clinical features of enteric salmonellosis, coronavirus, and neorickettsiosis. Objective: To identify risk factors for laminitis and nonsurvival to discharge in horses with enteric salmonellosis, coronavirus, or neorickettsiosis. Methods: Eighty-five horses hospitalized for acute colitis from 2011 to 2019. Methods: Retrospective case series. Medical record review (2011-2019) of adult (≥2 years) horses with colitis. Pri...
Use of polyamide cable ties during experimental omentectomy in adult horses with histopathological assessment. To report the use of nylon cable ties (NCT) for omentectomy in the horse. Methods: Experimental study. Methods: Eight healthy adult horses. Methods: Horses underwent nylon cable tie (NCT) ligation of the greater omentum after ventral midline celiotomy. The time required to complete the omentectomy was recorded. Horses were recovered for 14 days before repeat celiotomy, adhesions assessment, and histological examination of the omentectomy site using a proposed histologic grading scheme. The total time for omentectomy procedure and histologic score was assessed for normality. Data are expresse...
Evaluation of Villus Synovium From Unaffected Metacarpophalangeal Joints of Adult and Juvenile Horses. Horses are a widely accepted model for osteoarthritis (OA) research. Synovial tissue sampling is commonly used in studies to evaluate and grade the progress of OA or to assess treatment effects. Synovial explants play an important role in ex-vivo studies, increasingly replacing the use of living animals. To understand histomorphological changes in the process of joint-related diseases such as OA, detailed information about histomorphometric parameters of unaffected synovial villi is necessary. The objective of the present study was to evaluate the mean width of the intimal synovial lining and ...