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.
Effects of dopamine antagonists on alfentanil-induced locomotor activity in horses. To determine whether specific dopamine receptor antagonists block alfentanil-induced locomotor stimulation in horses. Methods: Randomized, prospective, crossover experiment. Methods: Eight adult horses (462-604 kg). Methods: Doses of dopamine-1 (D1) (NNC 01-0756) and dopamine-2 (D2) antagonists (eticlopride) were selected in a pilot study prior to a three part, blinded, cross-over study. In part 1, horses received 7.5 micro g kg-1 eticlopride, 5 micro g kg-1 NNC 01-0756 or an equal volume of saline. In part 2, they received both antagonists and in part 3, acepromazine at 0.05 mg kg-1. Locomoto...
Flow cytometric analysis of peripheral blood mononuclear cells induced by experimental endotoxemia in horse. Cellular activation and functional cell surface markers were evaluated during experimentally-induced endotoxemia in healthy horses. Eight healthy adult horses were infused a low dose of endotoxin (lipopolysaccharide from Escherichia coli O26: B6, 30 ng/kg of body weight, IV) and five control horses were given an equivalent volume of sterile saline solution. Venous blood samples were collected for flow cytometric analysis of peripheral blood mononuclear cells (PBMCs) and to measure plasma endotoxin concentrations. Clinical signs of endotoxemia were recorded at 10, 20, 30, 40, 50 min, 1, 2, 3, 4...
Ultrasonography of peripheral nerves in the normal adult horse. A study of the ultrasonographic appearance and size of the sciatic, tibial, peroneal, suprascapular, radial, median, and ulnar nerves and a comparison with the anatomic size and location of these nerves in the normal adult horse is reported. Cadavers and live horses were studied. Landmarks for localization and techniques for nerve identification are described. The depth and diameter of each nerve at various locations and the success rate in imaging each nerve are reported. Statistically significant correlations were found between anatomically and ultrasonographically measured nerve depths and ...
Clinical observations during induction and recovery of xylazine-midazolam- propofol anesthesia in horses. To evaluate clinical usefulness of xylazine (1.0 mg/kg)-midazolam (20 microg/kg)-propofol (3.0 mg/kg) anesthesia in horses, 6 adult Thoroughbred horses were examined. The quality of induction varied from poor to excellent and 5 out of 6 horses presented myotonus in the front half of the body. However, paddling immediately after induction observed in other reports of equine propofol anesthesia was not observed. Recovery time was 35.3 +/- 9.3 min and the quality of recovery was calm and smooth in all horses. Respiration rate decreased after induction and hypoxemia was observed during lateral rec...
Immunologic analysis of blood samples obtained from horses and stored for twenty-four hours. To determine whether immune function can be accurately assessed in blood samples obtained from horses and refrigerated overnight and whether a nonradioactive lymphocyte proliferation assay can be used to evaluate samples obtained from horses. Methods: 224 blood samples from 28 clinically normal adult horses. Methods: Heparinized blood samples were collected. Each sample was divided into 2 equal aliquots. One aliquot was refrigerated overnight to simulate overnight shipping of blood samples, and the other aliquot was evaluated on the day of blood collection. Lymphocytes were isolated and enumer...
Evaluation of different doses of propofol in xylazine pre-medicated horses. To characterize responses to different doses of propofol in horses pre-medicated with xylazine. Methods: Six adult horses (five females and one male). Methods: Each horse was anaesthetized four times with either ketamine or propofol in random order at 1-week intervals. Horses were pre-medicated with xylazine (1.1 mg kg-1 IV over a minute), and 5 minutes later anaesthesia was induced with either ketamine (2.2 mg kg-1 IV) or propofol (1, 2 and 4 mg kg-1 IV; low, medium and high doses, respectively). Data were collected continuously (electrocardiogram) or after xylazine administration and at 5, 1...
Analysis of anamnestic immune responses in adult horses and priming in neonates induced by a DNA vaccine expressing the vapA gene of Rhodococcus equi. Rhodococcus equi remains one of the most important pathogens of early life in horses, yet conventional vaccines to prevent rhodococcal pneumonia have not been successful. DNA vaccination offers an alternative to conventional vaccines with specific advantages for immunization of neonates. We developed a DNA vaccine expressing the vapA gene (pVR1055vapA) that induced an anamnestic response characterized by virulence associated protein A (VapA)-specific IgG antibodies in sera and bronchoalveolar lavage fluid (BALF) as well as VapA-specific proliferation of pulmonary lymphocytes when tested in adu...
Thyroid function in mature horses ingesting endophyte-infected fescue seed. To determine whether ingestion of fescue seed infected with the endophyte Neotyphodium coenophialum would alter thyroid function in adult horses. Methods: Original study. Methods: 4 adult mares that were not pregnant and 6 adult geldings. Methods: Thyrotropin releasing hormone stimulation tests were performed while horses received a standard diet and after infected seed (2.3 kg/d [5 lb/d]) had been fed for 1 and 2 months. Serum prolactin concentrations were measured to verify endophyte absorption. Results: Serum prolactin concentrations indicated that at least 8 of 10 horses absorbed the endop...
Pregnancy: a cloned horse born to its dam twin. Several animal species, including sheep, mice, cattle, goats, rabbits, cats, pigs and, more recently, mules have been reproduced by somatic cell cloning, with the offspring being a genetic copy of the animal donor of the nuclear material used for transfer into an enucleated oocyte. Here we use this technology to clone an adult horse and show that it is possible to establish a viable, full-term pregnancy in which the surrogate mother is also the nuclear donor. The cloned offspring is therefore genetically identical to the mare who carried it, challenging the idea that maternal immunological rec...
Effects of topical perineural capsaicin in a reversible model of equine foot lameness. Capsaicin is a local substance P depleter with dramatic analgesic effects. We tested the hypothesis that the topical application of capsaicin ointment over the palmar digital nerves would attenuate the clinical effects of a reversible model of equine foot lameness. Seven healthy adult horses shod unilaterally with adjustable heart bar shoes were studied in a crossover design for 2 weeks. Grade 5.0/5.0 lameness (nonweight bearing) was induced by tightening the adjustable heart bar shoe. One hour later, capsaicin ointment was applied over the medial and lateral palmar digital nerves 3 cm proxima...
Plasma profiles of ivermectin in horses following oral or intramuscular administration. A study was undertaken in order to evaluate and compare ivermectin's (IVM) plasma disposition kinetic parameters after oral or intramuscular (IM) administration in horses. Ten clinically healthy adult horses, weighing 380-496 kg body weight (BW), were allocated to two experimental groups of five horses. Group I, was treated with an oral paste formulation of IVM at the manufacturer's recommended dose of 0.2 mg/kg BW. Group II, was treated IM with an injectable 1% formulation of IVM at a dose of 0.2 mg/kg BW. Blood samples were collected by jugular puncture at different times between 0.5 h and 7...
Effects of hypothyroidism and withholding of feed on plasma lipid concentrations, concentration and composition of very-low-density lipoprotein, and plasma lipase activity in horses. To evaluate selected concentrations of blood lipids and lipase activities in euthyroid and hypothyroid horses deprived of feed for 96 hours. Methods: 4 healthy adult mares and 4 thyroidectomized adult mares. Methods: Horses were deprived of feed for 96 hours. Blood samples were collected at 24-hour intervals and analyzed to determine concentrations of non-esterified fatty acid (NEFA), triglyceride (TG), total cholesterol (TC), and very-low-density lipoprotein (VLDL) as well as composition of VLDL. Plasma lipase activities were measured after feed was withheld for 96 hours and 12 days after res...
Submural histopathologic changes attributable to peracute laminitis in horses. To describe submural histopathologic changes attributable to peracute laminitis in horses. Methods: 20 adult horses. Methods: A concurrent-control design was used to compare laminar lesions in 10 horses subjected to carbohydrate-induced laminitis with laminar characteristics of 10 sex- and aged-matched control horses with normal feet. Horses in the treatment group were administered an overload of carbohydrate. Tissues were obtained by biopsy 4 to 8 hours after onset of lameness or 72 hours after administration of the carbohydrate overload when lameness did not develop. Sections were stained wi...
Influence of topically applied cold treatment on core temperature and cell viability in equine superficial digital flexor tendons. To determine rate and degree of cooling for the superficial digital flexor tendon (SDFT) during a standard cryotherapy application in horses and evaluate in vitro effects of cooling on survival of tendon cells. Methods: 6 limbs of 5 adult horses and cultured cells obtained from SDFT of 3 adult horses during necropsy. Methods: In vivo data were acquired by use of a thermocouple temperature probe inserted into the SDFT of a forelimb of each standing sedated horse. After baseline temperatures were recorded, a commercial compression splint with circulating coolant was placed on each selected limb,...
Assessment of clinical characteristics, management practices, and activities of geriatric horses. To describe the demographic and clinical characteristics, management practices, and owner perception of a population of geriatric horses, and to compare these data with findings in a group of younger horses. Methods: Original study. Methods: 218 horses. Methods: Data were collected via a survey tool from owners of 165 horses that were > or = 20 years of age and 53 horses that were < 20 years of age. Results: Compared with young horses, the geriatric group included a significantly greater number of ponies; geriatric horses were also more likely to have a history of colic, dental disease, ...
Comparison of nociceptive withdrawal reflexes and recruitment curves between the forelimbs and hind limbs in conscious horses. To compare nociceptive withdrawal reflexes (NWRs) evoked from the distal aspect of the left forelimb and hind limb in conscious standing horses and to investigate NWR recruitment for graded electrical stimulation intensities. Methods: 20 adult horses. Methods: Surface electromyographic (EMG) activity evoked by transcutaneous electrical stimulation of the digital palmar (or plantar) nerve was recorded from the common digital extensor and cranial tibial muscles. Stimuli consisted of 25-millisecond train-of-5 constant current pulses. Current intensity was gradually increased until NWR threshold i...
Serum IgM concentrations in normal, fit horses and horses with lymphoma or other medical conditions. The purposes of this study were to (1) prospectively establish serum IgM and IgG concentrations in normal, fit, adult horses over time and (2) determine the accuracy of serum IgM concentrations for diagnosing lymphoma. Serial IgM and IgG concentrations were measured with a radial immunodiffusion assay in 25 regularly exercised horses at 6-week intervals. Horses had serum IgM concentrations ranging from 50 to 242 mg/dL over 5 months, with 20% of horses having IgM < or = 60 mg/dL. The normal range for IgM in fit horses should be considered 103 +/- 40 mg/dL and a cut-point for an IgM deficiency, ...
The effect of perineural anesthesia on infrared thermographic images of the forelimb digits of normal horses. Infrared thermography is an imaging modality gaining popularity as a diagnostic aid in the evaluation of equine lameness. Anecdotal reports of skin hyperthermia induced by local anesthesia, detected by thermography, have been made; however, no controlled studies have been reported. The purpose of this study was to examine the effects of perineural anesthesia on infrared thermographic images of the forelimb digits in normal horses. After environmental acclimation, infrared thermographs were made at intervals of 0, 5, 10, 15, 30, and 45 min from administration of mepivacaine hydrochloride or pho...
Corneal esthesiometry in the healthy horse. To determine corneal sensitivity in healthy adult horses in order to establish reference values. Methods: One hundred eyes of 50 healthy adult horses. Methods: Corneal sensitivity was determined by evaluating the corneal touch threshold (CTT) in five different corneal regions using a Cochet-Bonnet esthesiometer. Results: Comparing CTT values (in mm filament length) of the five prescribed corneal regions revealed regional variations in corneal sensitivity, with the central region (21.15 +/- 6.23 mm) being the most sensitive, followed by the nasal (20.75 +/- 5.14 mm), temporal (20.70 +/- 5.37 mm...
Influence of dietary beetpulp on the plasma level of triacylglycerols in horses. In a cross-over study with six adult horses, the effect of isoenergetic replacement of dietary glucose by beetpulp on the concentration of plasma triacylglycerols was studied. The test ration contained 25% beetpulp in the dietary dry matter. The feeding of beet pulp lowered plasma triacylglycerol concentrations (p = 0.058) in the fasting state and raised the activity of heparin-released lipoprotein lipase (LPL) (p = 0.059) and the concentration of HDL2 cholesterol (p = 0.058). In the fasting state, the plasma concentrations of free fatty acids (p = 0.073) and those of beta-hydroxybutyrate (p =...
Lower airway diseases of the adult horse. Lower airway problems of the adult horse are commonly encountered by the practitioner. Particularly susceptible populations include horses transported for any significant distance and young horses grouped together for training and/or competition. This article presents some of the commonly encountered problems of this patient population, including bacterial pneumonia/pleuropneumonia and influenza, and some uncommon ones, including pulmonary edema, pneumothorax/hemothorax, and acuterespiratory distress syndrome. Information is presented that should allow the practitioner to diagnose these proble...
Immunoglobulin G subisotype responses of pneumonic and healthy, exposed foals and adult horses to Rhodococcus equi virulence-associated proteins. Rhodococcus equi causes severe pyogranulomatous pneumonia in foals and in immunocompromised humans. Replication of virulent isolates within macrophages correlates with the presence of a large plasmid which encodes a family of seven virulence-associated proteins (VapA and VapC to VapH), whose functions are unknown. Although cell-mediated immunity is thought to be crucial in eliminating R. equi infection, antibody partially protects foals. The antibody response to both VapA and VapC was similar in six adult horses and six naturally exposed but healthy foals, as well as in eight foals with R. equ...
Ultrasonographic findings in horses with right dorsal colitis: five cases (2000-2001). To determine whether ultrasonography would be useful in the diagnosis of right dorsal colitis in horses. Methods: Retrospective study. Methods: 5 horses with right dorsal colitis and 15 healthy adult horses. Methods: Mural thickness and appearance of the right dorsal colon were determined from ultrasonographic images obtained at right intercostal spaces 10, 11, 12, 13, and 14. Results: The right dorsal colon could be imaged most consistently at the right 11th, 12th, and 13th intercostal spaces, below the margin of the lung and axial to the liver. Mural thickness measured from ultrasonographic ...
Computed tomographic anatomy of the equine tarsus. The purpose of this study was to provide a detailed computed tomographic (CT) anatomic reference for the equine tarsus. CT examinations of the tarsal regions from four clinically and radiographically normal adult horses, which were euthanized for reasons not related to musculoskeletal disease, were included in the study. Limbs were removed at the level of midtibia, and 3-mm contiguous transverse CT images were obtained, starting at a level proximal to the tuber calcanei and continuing distally into the proximal metatarsus. Soft tissue and bone windows were used to image different anatomic feat...
Preliminary investigation of the probiotic potential of Lactobacillus rhamnosus strain GG in horses: fecal recovery following oral administration and safety. This study was designed to evaluate whether Lactobacillus rhamnosus strain GG (LGG), an extensively studied probiotic organism in humans, can colonize the intestines of adult horses and foals. Lactobacillus rhamnosus strain GG was administered to adult horses at doses of 1 x 10(9) CFU/50kg bodyweight (BW)/day (group 1, 7 horses), 1 x 10(10) colony forming units/ 50kg BW/day (group 2, 7 horses) and 5 x 10(10) colony forming units/50kg BW/day (group 3, 7 horses) for 5 d. Foals received 2 x 10(10) colony forming units/50kg BW/day (group 1, 7 foals) or 1 x 10(11) colony forming units/50kg BW/day (...
Effects of hydrochloric, valeric, and other volatile fatty acids on pathogenesis of ulcers in the nonglandular portion of the stomach of horses. To identify in vitro effects of hydrochloric acid, valeric acid, and other volatile fatty acids (VFAs) on the pathogenesis of ulcers in the nonglandular portion of the equine stomach. Methods: Gastric tissues from 13 adult horses. Methods: Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance and conductance calculated after tissues were bathed in normal Ringer's solution (NRS) or NRS and hydrochloric, valeric, acetic, propionic, and butyric acids. Treated tissues were examined histologica...
Effect of the number of passages of fetal and adult fibroblasts on nuclear remodelling and first embryonic division in reconstructed horse oocytes after nuclear transfer. The effects of repeated passage in vitro of fetal fibroblast cells (FFC) and adult fibroblast cells (AFC) on nuclear remodelling and first embryonic division when used to reconstruct horse oocytes, and the reasons for the developmental block in progression to the two-cell stage were investigated. A total of 463 metaphase II oocytes produced 427 fibroblast-cytoplasm couplets after nuclear transfer, which finally resulted in 319 reconstructed oocytes. With increasing numbers of passages, the rates of nuclear remodelling decreased in both types of donor cell; about half of the fused donor cell nu...