Equine metabolism encompasses the biochemical processes that occur within horses to maintain life, including the conversion of food into energy, the synthesis of necessary compounds, and the elimination of waste products. These processes are essential for supporting various physiological functions such as growth, reproduction, and physical performance. Key components of equine metabolism include carbohydrate, fat, and protein metabolism, each of which contributes to the overall energy balance and health of the horse. Factors influencing metabolic rate and efficiency in horses include age, breed, diet, exercise, and health status. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of metabolic processes in equine physiology.
Dakin SG, Dudhia J, Werling NJ, Werling D, Abayasekara DR, Smith RK.The contribution of inflammation to the pathogenesis of tendinopathy and high prevalence of re-injury is not well established, although recent evidence suggests involvement of prostaglandins. We investigated the roles of prostaglandins and inflammation-resolving mediators in naturally occurring equine tendon injury with disease stage and age. Levels of prostaglandins E(2) (PGE(2)), F(2α) (PGF(2α)), lipoxin A(4) (LXA(4)) and its receptor FPR2/ALX were analysed in extracts of normal, sub-acute and chronic injured tendons. To assess whether potential changes were associated with altered PGE(2) ...
McGowan CM, Dugdale AH, Pinchbeck GL, Argo CM.Few studies have examined the effect of dietary restriction in horses with equine metabolic syndrome (EMS). This study aimed to determine improvements in insulin sensitivity following dietary restriction for 6 weeks, and to determine if the improvement would be greater in horses receiving short-chain fructo-oligosaccharides (sc-FOS). Dietary management involved feeding grass hay, restricted to 1.25% of body mass (BM) as daily dry matter intake and soaked in cold water prior to feeding, with the addition of a vitamin and mineral nutraceutical supplement with or without the addition of sc-FOS (1...
Peters LM, Demmel S, Pusch G, Buters JT, Thormann W, Zielinski J, Leeb T, Mevissen M, Schmitz A.Ketamine is an anesthetic and analgesic regularly used in veterinary patients. As ketamine is almost always administered in combination with other drugs, interactions between ketamine and other drugs bear the risk of either adverse effects or diminished efficacy. Since cytochrome P450 enzymes (CYPs) play a pivotal role in the phase I metabolism of the majority of all marketed drugs, drug-drug interactions often occur at the active site of these enzymes. CYPs have been thoroughly examined in humans and laboratory animals, but little is known about equine CYPs. The characterization of equine CYP...
De Pedro P, Wilkins PA, McMichael MA, Dirikolu L, Lascola KM, Clark-Price SC, Boston RC.To determine endogenous production of L-lactate and the clearance of exogenous sodium L-lactate (ExLC) in healthy adult horses. Methods: A sodium L-lactate solution (1 mmol/kg body weight qs to 500 mL final volume in 0.9% NaCl) was adminstered IV over 15 minutes. Blood samples for L-lactate concentration [LAC] measurement were collected immediately prior to infusion, at 5, 10, and 15 minutes during infusion and at 1 minute intervals for 15 minutes, at 30, 45, 60, 120, and 180 minutes postinfusion. Disposition modeling and pharmacokinetic analysis was performed using proprietary software. Metho...
Franklin SH, Van Erck-Westergren E, Bayly WM.Horses are elite athletes when compared with other mammalian species. In the latter, performance is limited by cardiovascular or musculoskeletal performance whereas in athletic horses it is the respiratory system that appears to be rate limiting and virtually all horses exercising at high intensities become hypoxaemic and hypercapnoeic. This is due to both diffusion limitation and a level of ventilation inadequate for the metabolic level that enables horses to exercise at these intensities. In conjunction with these blood gas changes, total pulmonary resistance increases and the work of breath...
Katz LM, Bailey SR.With the increasing number of studies being published on the different experimental models used to induce and study acute laminitis, the pathophysiological events associated with these various models (i.e. starch overload, oligofructose overload, black walnut extract and hyperinsulinaemia) can be compared more realistically. Within this review, the mechanisms for metabolic vs. inflammatory laminitis are discussed, and the question of how pasture laminitis may fit into any of the proposed mechanisms is addressed.
Kitaoka Y, Mukai K, Aida H, Hiraga A, Masuda H, Takemasa T, Hatta H.To investigate the effects of high-intensity training (HIT) on carbohydrate and fat metabolism in Thoroughbreds. Methods: 12 Thoroughbreds (3 to 4 years old; 6 males and 6 females). Methods: Horses performed HIT for 18 weeks. They ran at 90% or 110% of maximal oxygen consumption ((V)O(2max)) for 3 minutes (5 d/wk) and were subjected to incremental exercise testing (IET) before and after training. Blood samples were collected during IET, and muscle samples were obtained from the gluteus medius muscle immediately after IET. Phosphofructokinase, citrate synthase, and β-3-hydroxyacyl CoA dehydrog...
Jellyman JK, Allen VL, Holdstock NB, Fowden AL.Studies in humans and animals have linked abnormal programming of adult tissue function to excess glucocorticoids during perinatal development. The current study investigated the hypothesis that physiological variations in glucocorticoid concentrations during early neonatal life of the foal alter the secretory responses of the pancreatic β cells 2 and 12 wk after treatment. Spontaneously delivered foals received either saline or long-acting ACTH for 5 d from 1 d after birth to maintain an endogenous rise in cortisol concentrations. Starting at d 10, pancreatic β cell function was studied usi...
Sekkin S, Gokbulut C, Kum C, Karademir U.This study was designed to investigate the plasma disposition and systemic availability of enrofloxacin (ENR) following intramuscular and intravenous administrations. Six donkeys (Equus asinus) were used in this study. The animals were allocated into two groups (intramuscular and intravenous groups). After a 2-week washout period, the experiment was repeated with the groups reversed according to a two-phase crossover design. In phase I, group I received intravenously the commercially available injectable solution of ENR at the dose of 5 mg/kg and group II received intramuscularly the same ENR ...
Ungru J, Blüher M, Coenen M, Raila J, Boston R, Vervuert I.Fifteen obese ponies were used in a body weight (BW) reduction programme (BWRP, daily energy intake: 7.0-8.4 MJ/100 kg BW). A frequently sampled intravenous glucose tolerance test was used to assess insulin sensitivity. Subcutaneous adipose tissue biopsies of the tail head were obtained for mRNA gene expression profiles of adiponectin, retinol-binding protein 4 (RBP4), interleukin 6 (IL-6) and macrophage activation marker (CD68) before and after BWRP. Blood samples were analysed for serum leptin, serum RBP4 and plasma adiponectin. Significant BW losses occurred with 7 MJ DE/100 kg BW. Serum le...
Santos AS, Ferreira LM, Martin-Rosset W, Cotovio M, Silva F, Bennett RN, Cone JW, Bessa RJ, Rodrigues MA.To access the fermentative response of equine caecal microbial population to nitrogen availability, an in vitro study was conducted using caecal contents provided with adequate energy sources and nitrogen as limiting nutrient. Two nitrogen (N) sources were provided, protein (casein) and non-protein (urea). Caecal fluid, taken from three cannulated horses receiving a hay-concentrate diet, was mixed with a N-free buffer-mineral solution. The influence of four N levels (3.7, 6.3, 12.5 or 25 mg of N in casein or urea) was studied using the gas production technique. Total volatile fatty acids (VFA)...
Casella S, Piccione D, Ielati S, Bocchino EG, Piccione G.The aim of this study was to assess the anion transport in equine erythrocytes through the measurement of the sulfate uptake operating from band 3 using different experimental temperatures and buffer solutions. Blood samples of six clinically healthy horses were collected via jugular vein puncture, and an emochrome-citometric examination was performed. The blood was divided into four aliquots and by centrifugation and aspiration the plasma and buffy coat were carefully discarded. The red blood cells were washed with an isosmotic medium and centrifuged. The obtained cell suspensions were incuba...
Ho EN, Kwok WH, Lau MY, Wong AS, Wan TS, Lam KK, Schiff PJ, Stewart BD.A veterinary preparation known as TB-500 and containing a synthetic version of the naturally occurring peptide LKKTETQ has emerged. The peptide segment (17)LKKTETQ(23) is the active site within the protein thymosin β(4) responsible for actin binding, cell migration and wound healing. The key ingredient of TB-500 is the peptide LKKTETQ with artificial acetylation of the N-terminus. TB-500 is claimed to promote endothelial cell differentiation, angiogenesis in dermal tissues, keratinocyte migration, collagen deposition and decrease inflammation. In order to control the misuse of TB-500 in equin...
Tydén E, Löfgren M, Hakhverdyan M, Tjälve H, Larsson P.In the present study, we examined the gene expression of cytochrome P450 3A (CYP3A) isoenzymes in the tracheal and bronchial mucosa and in the lung of equines using TaqMan probes. The results show that all seven CYP3A isoforms identified in the equine genome, that is, CYP3A89, CYP3A93, CYP3A94, CYP3A95, CYP3A96, CYP3A97 and CYP3A129, are expressed in the airways of the investigated horses. Though in previous studies, CYP3A129 was found to be absent in equine intestinal mucosa and liver, this CYP3A isoform is expressed in the airways of horses. The gene expression of the CYP3A isoenzymes varied...
Borer KE, Bailey SR, Menzies-Gow NJ, Harris PA, Elliott J.Identification of ponies (Equus caballus) at increased risk of pasture-associated laminitis would aid in the prevention of the disease. Insulin resistance has been associated with laminitis and could be used to identify susceptible individuals. Insulin resistance may be diagnosed by feeding supplementary water-soluble carbohydrate (WSC) and measuring blood glucose and insulin concentrations. The aim of this study was to assess the glycemic and insulinemic responses of 7 normal (NP) and 5 previously laminitic (PLP), mixed breed, native UK ponies fed glucose, fructose, and inulin [1 g/(kg·d) fo...
Raeside JI, Christie HL, Waelchli RO, Betteridge KJ.The embryo proper in early equine pregnancy has recently been shown to have a remarkable capacity for metabolism of oestrogens. High concentrations of oestrogens in yolk-sac fluid could provide substrate for local metabolism in tissues of the embryo proper and this activity could have significance for early development. Due to the high level of oestrogen metabolism in the embryo proper we examined the possibility that it could also biosynthesise oestrogens. Conceptuses were collected in the fourth week of pregnancy (n=23) and the embryo was separated from extraembryonic tissues for incubation ...
Wong DM, Moore RM, Brockus CW.Oxygen is essential to aerobic life, but it is also associated with the production of highly reactive compounds that can pose danger to physiologic systems when the oxygen concentration is excessive. Reactive oxygen species (ROS) are required for normal physiologic processes, but when produced in excess, they can overwhelm endogenous antioxidants, resulting in significant cellular damage and, eventually, cell death. Ischemic events can initiate numerous pathophysiologic mechanisms leading to increased production of ROS, loss of cellular energy production, and lipid peroxidation. Although reper...
Patan-Zugaj B, Gauff FC, Licka TF.To examine the effect of endotoxins on metabolism and histopathologic changes of isolated perfused equine forelimbs. Methods: Forelimbs (comprising the metacarpus and digit) were collected from cadavers of 12 healthy adult horses after slaughter at an abattoir (14 limbs; 1 forelimb of 10 horses and both forelimbs of 2 horses). Methods: Forelimbs were perfused for 10 hours with autologous blood, with and without the addition of endotoxin (80 ng of lipopolysaccharide [LPS]/L). Two limbs of the endotoxin exposure group and 2 nonperfused limbs were loaded to failure of the suspensory apparatus of ...
de Graaf-Roelfsema E, Keizer HA, van Breda E, Wijnberg ID, van der Kolk JH.To determine the influence of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in horses and identify potential markers indicative of early overtraining. Methods: 12 Standardbred geldings. Methods: Horses underwent 4 phases of treadmill-based training. In phase 1, horses were habituated to the treadmill. In phase 2, endurance training was alternated with high-intensity exercise training. In phase 3, horses were divided into control and intensified training groups. In the intensified training group, training intensity, duration, ...
Murase H, Sakai S, Kusano K, Hobo S, Nambo Y.Zinc is one of the essential microelements involved in the regulation of enzyme activity, as well as metabolism of nucleic acid and proteins. There have been few reports on equine serum zinc concentrations during the training period, and little is known about the relationship between zinc levels and diseases in horses. In this study, we measured serum zinc levels in healthy Thoroughbred racehorses, as well as in other horses, under general disease or training conditions. The reference value for serum zinc levels in Thoroughbred horses was 41-79 μg/dl. There were no differences in serum zinc l...
Kuhn M, Guschlbauer M, Feige K, Schluesener M, Bester K, Beyerbach M, Breves G.Equine typholocolitis is a sporadic diarrheal disease causing high mortality rates. One of the risk factors responsible for this is the oral application of the macrolide antibiotic erythromycin. The aim of the present in vitro study was to investigate whether erythromycin in combination with feed restriction provokes changes in microbial hindgut metabolism and could therefore be involved in the pathogenesis of equine typhlocolitis. As application of erythromycin and feed restriction are risk factors for equine typhlocolitis, both factors were chosen to investigate their individual and combined...
Finno CJ, Valberg SJ.Vitamin E is a primary chain-breaking antioxidant that prevents cyclic propagation of lipid peroxidation. Across species, vitamin E is essential for normal neuromuscular function by acting as a potent antioxidant, as well as by modulating the expression of certain genes, inhibiting platelet aggregation and stabilizing plasma membranes. This review focuses on vitamin E structure, absorption, metabolism, current equine dietary recommendations, the interplay between antioxidants and exercise, a discussion of the necessity of vitamin E supplementation in the horse above the Nutritional Research Co...
Bertin FR, Sojka-Kritchevsky JE.Equine insulin resistance is important because of its association with laminitis. The insulin-response test is described to diagnose insulin resistance in clinical settings. Practitioners may be reluctant to perform this test because of the time needed for the test and the fear of inducing hypoglycemia. The objective of the study was to compare a 2-step insulin-response test with a complete insulin-response test. A complete insulin-response test was performed on 6 insulin-resistant horses and 6 controls. A 2-step insulin-response test consisting of an intravenous injection of 0.1 IU/kg human i...
Lamprecht ED, Williams CA.Objectives were to evaluate effects of (1) repetitive arthrocentesis on biomarkers of inflammation (prostaglandin E(2), PGE(2)) and aggrecan synthesis (chondroitin sulfate-846; CS) in synovial fluid (SF); (2) exercise and superoxide dismutase (SOD) supplementation on biomarkers of inflammation, antioxidant status, and aggrecan synthesis, in horses. Preliminary trial. Standardbreds underwent four arthrocentesis procedures within 48 h and exhibited elevated CS and no changes in PGE(2). Exercise trial. this randomized crossover design used twelve Standardbred mares which received either treatment...
Wooldridge AA, Edwards HG, Plaisance EP, Applegate R, Taylor DR, Taintor J, Zhong Q, Judd RL.To characterize adiponectin protein complexes in lean and obese horses. Methods: 26 lean horses and 18 obese horses. Procedures-Body condition score (BCS) and serum insulin activity were measured for each horse. Denaturing and native western blot analyses were used to evaluate adiponectin complexes in serum. A human ELISA kit was validated and used to quantify high-molecular weight (HMW) complexes. Correlations between variables were made, and HMW values were compared between groups. Results: Adiponectin was present as a multimer consisting of HMW (> 720-kDa), low-molecular weight (180-kDa)...
Wagner AL, Urschel KL.To determine whether feeding-induced activation of translation initiation factors, specifically protein kinase B, ribosomal protein S6 kinase (S6K1), ribosomal protein S6 (rpS6), and eukaryotic initiation factor 4E binding protein 1, in horses is affected by age. Methods: 6 yearlings, six 2-year-old horses, and 6 mature horses. Methods: After an 18-hour period of feed withholding, horses consumed a high-protein meal (2 g/kg) at time 0 and 30 minutes (postprandial state) or continued to have feed withheld (postabsorptive state). Blood samples were collected for the duration of the experimental ...
Echigoya Y, Morita S, Itou T, Sakai T.To evaluate effects of extracellular lactate on viability, shape change, lactate metabolism, and reactive oxygen species (ROS) production in equine polymorphonuclear leukocytes (PMNs). Methods: PMNs isolated from equine venous blood samples. Methods: PMNs were incubated with 0 to 300mM lactate for 30 minutes before each experiment. Viability was assessed via trypan blue exclusion. Shape change was assessed via flow cytometry and light microscopy. Relative quantification of monocarboxylic acid transporter and lactate dehydrogenase lactate dehydrogenase (LDH) isotype mRNAs was performed with a r...
Waller AP, Huettner L, Kohler K, Lacombe VA.Although insulin resistance (IR) has been increasingly recognized in horses, a clear understanding of its pathophysiology is lacking. The purpose of the present study was to determine the early pathologic changes in IR horses by characterizing alterations in proteins that play key roles in innate immunological responses and inflammatory pathways, and by identifying potential links with glucose transport and insulin signaling. Visceral (VIS) and subcutaneous (SC) adipose tissue and skeletal muscle (SM) biopsies were collected from horses, which were classified as insulin-sensitive (IS) or IR ba...
Brunner J, Wichert B, Burger D, von Peinen K, Liesegang A.This study aims at the comparison of the actual feeding of horses with the recommendations from the literature, and it studies the effects of feeding and exercise on several blood metabolic parameters before and after exercise. Blood samples were collected from 25 horses during one-star eventing competitions and evaluated for blood glucose, insulin, lactate, free fatty acids and triglyceride levels. Questionnaires on the feeding practices of the horses were evaluated. The questionnaires revealed that during training, and on tournament days, horses received on average 4.3 kg of concentrate per ...
Shrestha HK, Beg MA, Burnette RR, Ginther OJ.Horses are about five times more sensitive to the luteolytic effect of prostaglandin F2alpha (PGF) than cattle, as indicated by a recommended clinical dose of 5 mg in horses and 25 mg in cattle. Novel evaluations of the PGF plasma disappearance curves were made in mares and in heifers, and the two species were compared. Mares and heifers (n = 5) of similar body weight were injected (Min 0) intravenously with PGF (5 mg per animal). Blood was sampled every 10 sec until Min 3, every 30 sec until Min 5, every 10 min until Min 60, and every 30 min until Min 240. The mean PGF concentration was great...
Stefanini S, Chiancone E, Vecchini P, Antonini E.Iron uptake and micelle formation in ferritin and apoferritin have been followed both spectrophotometrically and by means of sedimentation velocity experiments. Information was thus obtained on the molecular weight distribution of the reconstitution product. To achieve incorporation 'native' ferritin (whole ferritin as purified from horse spleen), 'native' apoferritin (apoferritin prepared by fractionation of ferritin preparations) and 'reduced' apoferritin (apoferritin prepared by reduction of ferritin by dithionite or ascorbic acid) have been incubated with ferrous salts in the presence of o...
Many colic horses are compromised due to the disease state and from hours of starvation and sometimes long trailer rides. This could influence their muscle energy reserves and affect the horses' ability to recover. The principal aim was to follow metabolic parameter before, during, and up to 7 days after anaesthesia in healthy horses and in horses undergoing abdominal surgery due to colic. Methods: 20 healthy horses given anaesthesia alone and 20 colic horses subjected to emergency abdominal surgery were anaesthetised for a mean of 228 minutes and 183 minutes respectively. Blood for analysis o...
Sosa León LA, Davie AJ, Hodgson DR, Rose RJ.Effects of different tonicities, glucose concentrations and temperatures of an oral rehydration solution (ORS) on its uptake and elimination in resting horses were studied. Fluid and electrolyte deficits similar to those occurring during prolonged exercise were induced by the administration of 1 mg/kg bwt of frusemide i.m., 3 h prior to the ORS. Fluid was administered via nasogastric tube at a volume equivalent to 4% bodyweight, which approximated diuretic induced losses. The uptake of fluid was evaluated by changes in haematocrit (PCV) and plasma total protein concentration (TP). Changes in e...
McCoy DJ.Both ovaries in a 10-year-old American Saddle Horse mare were determined to be larger than normal. The mare had problems with infertility during the preceding 3 years. Clinical evaluation revealed that the mare was polyuric, polydypsic, hyperinsulinemic, and hyperglycemic, and had reduced tolerance to exogenous glucose. Bilateral granulosa cell tumors were identified on histologic examination of the ovaries. The precise mechanism for the secondary diabetes mellitus was not determined; however, the cause was suspected to be a result of the synthesis and release of a hormonal substance by the tu...
Martín Muñoz P, Anel-López L, Ortiz-Rodríguez JM, Álvarez M, de Paz P, Balao da Silva C, Rodríguez Martinez H, Gil MC, Anel L, Peña FJ....Oxidative stress is a major factor explaining sperm dysfunction of spermatozoa surviving freezing and thawing and is also considered a major inducer of a special form of apoptosis, visible after thawing, in cryopreserved spermatozoa. To obtain further insights into the link between oxidative stress and the induction of apoptotic changes, stallion spermatozoa were induced to oxidative stress through redox cycling after exposure to 2-methyl-1,4-naphthoquinone (menadione), or hydroxyl radical formation after FeSO exposure. Either exposure induced significant increases (p < 0.05) in two marke...
Calamari L, Abeni F, Bertin G.This study was conducted to determine the effects of dietary Se source and dose on metabolic and hematological profiles, and their relationships with oxidative status in horses. Twenty-five mature horses were blocked by BW and randomly allocated to 1 of 5 dietary treatments: negative control (CTRL: 0.085 mg of Se/kg of DM), 3 different dietary concentrations of organic Se provided by Se yeast (SY02, SY03, and SY04 containing 0.2, 0.3, and 0.4 mg of total Se/kg of DM, respectively), and 1 positive control provided by sodium selenite (SS03 containing 0.3 mg of total Se/kg of DM). Horses were fed...
Ward LC, White KJ, van der Aa Kuhle K, Cawdell-Smith J, Bryden WL.Assessment of equine body composition using objective measurements is difficult owing to the large size of the animals and the costs involved. Bioelectrical impedance spectroscopy (BIS), a technique widely used for the assessment of body composition in humans, was investigated for practicality of use in horses. BIS uses algorithms that require values for the apparent resistivities of body fluids and body proportion factors (Kb), currently not available for horses. Aims of the present study were to derive resistivity coefficients and body proportion factors and to validate their use for predict...
Albornoz A, Alarcon P, Morales N, Uberti B, Henriquez C, Manosalva C, Burgos RA, Moran G.The present work characterized the metabolomic profile of bronchoalveolar lavage fluid (BALF) in healthy horses, experimentally-induced airway inflammation by lipopolysaccharide (LPS) nebulization, and naturally-occurring asthma (n = 3 in each group). All animals underwent clinical and upper airway endoscopic examinations, and bronchoalveolar lavage. BALF supernatant samples were subjected to metabolic analysis based on gas chromatography-mass spectrometry (GC-MS). Overall, 67 peaks were obtained from BALF GC-MS analysis, corresponding to 53 metabolites which were categorized according to ch...
Frean SP, Lees P.To investigate effects of the anti-arthritic agents hyaluronan and polysulfated glycosaminoglycan (PSGAG) on inflammatory metabolism in cultured equine synoviocytes. Methods: Synoviocytes cultured from samples obtained from the metacarpophalangeal joints of 4 horses. Methods: Equine synoviocytes were grown in monolayer culture. Synoviocytes were stimulated with lipopolysaccharide (LPS) and simultaneously treated with various concentrations of hyaluronan or PSGAG for 48 hours. Three hyaluronan preparations were compared. Prostaglandin E2 (PGE2) concentrations in culture medium were measured, us...
Snow DH, Mackenzie G.The effects of prolonged cantering before and after a 10 week training programme were studied in 6 horses. Determinations were carried on on venous blood for packed cell volume, glucose, glycerol, free fatty acids, beta-hydroxybutyrate, 11-hydroxycorticosteroids, pH and pCO2. Exercise caused a slight increase in glucose, lactate and pH, a moderate rise in PCV, glycerol and free fatty acids, and a marked rise in 11-hydroxycorticosteroids. A decrease in venous pCO2 occurred and a slight but not significant decrease in beta-hydroxybutyrate. Training was found to cause no significant difference in...
Hales EN, Habib H, Favro G, Katzman S, Sakai RR, Marquardt S, Bordbari MH, Ming-Whitfield B, Peterson J, Dahlgren AR, Rivas V, Ramirez CA, Peng S....Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disorder associated with a vitamin E deficiency within the first year of life. Vitamin E consists of 8 isoforms metabolized by the CYP4F2 enzyme. No antemortem diagnostic test currently exists for eNAD/EDM. Objective: Based on the association of α-tocopherol deficiency with the development of eNAD/EDM, we hypothesized that the rate of α-tocopherol, but not γ-tocopherol or tocotrienol metabolism, would be increased in eNAD/EDM-affected horses. Methods: Vitamin E metabolism: Proof...
Goachet AG, Julliand V.Measurements of respiratory exchanges in genuine exercise conditions are undoubtedly of interest to further define the energy needs of endurance horses. However, the equine K4b2, the gas exchanges portable device validated for equines, has not been used in Arabian endurance horses yet. Therefore, the objective of this study was to implement field cardio-respiratory measurements in such horses using the equine K4b2 in order to assess energy expenditure (EE). Measurements of heart rate (HR), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory frequency (RF), tidal volume (VT) and ...
Underwood C, Southwood LL, Walton RM, Johnson AL.To determine: (1) changes in blood ammonia, bile acid (BA), bilirubin, triglyceride, and glucose concentrations and liver enzyme activities in perioperative colic patients and (2) the association between these laboratory findings and short-term survival. Methods: Prospective observational clinical study. Methods: Thirty-two adult horses undergoing exploratory celiotomy for colic. Methods: None. Results: Blood samples were collected preoperatively and at 24-36 and 72-84 hours postoperatively and analyzed for blood ammonia, BA, bilirubin, triglyceride, and glucose concentrations and sorbitol deh...
Nimmo MA, Snow DH.To ascertain the effects of sprint and endurance exercise on the time course of skeletal muscle mitochondrial changes, an ultrastructural study was conducted on four Thoroughbred horses. Skeletal muscle biopsies were taken at various intervals during and after the exercise. Transient mitochondrial alterations of varying degrees were observed following both types of exercise and were considered to be related to the development of fatigue. The degree of distortion of mitochondrial structure is considered not to represent the in vivo condition but the state of responsiveness to the fixation mediu...
Elliott J, Berhane Y, Bailey SR.To determine in vitro vasoactive potency of monoamines formed in the cecum and found in the systemic circulation of horses. Methods: Segments of digital blood vessels obtained from 6 healthy mixed-breed horses and ponies euthanatized at an abattoir and platelets isolated from 4 healthy ponies. Methods: Paired rings of digital artery and vein from the same horse were examined, and isometric tension was recorded. Concentration-response curves for tryptamine (TRP), tyramine (TYR), phenylethylamine (PEA), isoamylamine (IAA), and isobutylamine (IBA) were obtained. Vasoconstrictor mechanisms were in...
Van den Hoogen BM, van de Lest CH, van Weeren PR, Lafeber FP, Lopes-Cardozo M, van Golde LM, Barneveld A.The purpose of this study was to determine whether changes in the synovial fluid (SF) induced by in vivo loading can induce an alteration in the metabolic activity of chondrocytes in vitro. Therefore, SF was collected from ponies after a period of box rest and after they had exercise for a week. Normal, unloaded articular cartilage explants were cultured in 20% solutions of these SFs for 4 days and chondrocyte activity was determined by glycosaminoglycan (GAG) turnover. In explants cultured in post-exercise SF, GAG synthesis was enhanced and GAG release was diminished when compared to cultures...
Fowden AL, Barnes RJ, Comline RS, Silver M.Insulin secretion and the factors influencing beta-cell function were investigated in the chronically catheterized fetal foal and mare during the second half of gestation. The response of the fetal beta cells to exogenous glucose was also examined. The mean concentration of insulin in the fetal foal was 7.5 +/- 0.5 (S.E.M.) microunit./ml (n = 20) which was significantly less than the corresponding maternal value of 49.0 +/- 5.0 microunit./ml (n = 20, P < 0.01). The insulin concentration in non-pregnant horses was 24.5 +/- 1.5 microunit./ml (n = 5) which was significantly less than the value...
Piccione G, Giannetto C, Assenza A, Casella S, Caola G.We examined the response to exercise of selected physiological variables in horses performing the identical routine for eight days, in the morning (a.m.) or in the afternoon (p.m.). Heart rate (HR), systolic and diastolic blood pressure (BP), and body temperature (BT) were all consistently greater in the p.m. For BP and BT, the absolute increase above the a.m. values was the same at rest and during exercise. For HR, the absolute increase was greater during exercise, but the percent increase was the same as during rest. During exercise, blood glucose decreased, while blood lactate and skin temp...
Hansson A, Knych H, Stanley S, Berndtson E, Jackson L, Bondesson U, Thevis M, Hedeland M.LGD-4033 has been found in human doping control samples and has the potential for illicit use in racehorses as well. It belongs to the pharmacological class of selective androgen receptor modulators (SARMs) and can stimulate muscle growth, much like anabolic steroids. However, SARMs have shown superior side effect profiles compared to anabolic steroids, which arguably makes them attractive for use by individuals seeking an unfair advantage over their competitors. The purpose of this study was to investigate the metabolites formed from LGD-4033 in the horse in order to find suitable analytical ...
Sánchez-Calabuig MJ, Fernández-González R, Hamdi M, Smits K, López-Cardona AP, Serres C, Macías-García B, Gutiérrez-Adán A.Equine embryos exhibit an unusual pattern of glucose tolerance in vitro and are currently cultured in hyperglycaemic conditions. Objective: Our main objective was to analyse the effect of different glucose concentrations on in vitro-produced equine embryo development and quality. Methods: Experiments comparing in vitro and in vivo produced embryos. Methods: Oocytes (n = 641) were collected from post-mortem ovaries, matured in vitro and fertilised by intracytoplasmic sperm injection (ICSI). Embryo culture was divided from Day 0 to Day 4 and from Day 4 to Day 9 in three groups: 5-10 (5 and 10...
Tiley HA, Geor RJ, McCutcheon LJ.To determine the effects of dexamethasone treatment on selected components of insulin signaling and glucose metabolism in skeletal muscle obtained from horses before and after administration of a euglycemic-hyperinsulinemic clamp (EHC). Methods: 6 adult Standardbreds. Methods: In a balanced crossover study, horses received either dexamethasone (0.08 mg/kg, IV, q 48 h) or an equivalent volume of saline (0.9% NaCl) solution, IV, for 21 days. A 2-hour EHC was administered for measurement of insulin sensitivity 1 day after treatment. Muscle biopsy specimens obtained before and after the EHC were a...
Ley WB, Scott Pleasant R, Dunnington EA.Studies evaluating nutritional and seasonal influences on hoof strength and composition in horses, as well as the scientific justification for feeding supplements to improve hoof quality, are lacking. The horseman and veterinarian need controlled studies in this area to make informed decisions. This project quantified, in 2 trials, relative elasticity, tensile strength, % moisture, and mineral composition of hooves of 48 mature Thoroughbred mares maintained on different nutritional/management regimens, sampled quarterly over 12 month periods. Tensile strength was positively associated with sul...
Miksík I, Deyl Z.Skin and aorta collagen specimens of Wistar rats, white mice, beagle dogs, cats, horses, and human necropsies of different ages were examined with respect to the content of glycated products. The data presented show that (a) glycation and accumulation of the chromophore(s) are comparable in collagen samples from different species of comparable age; (b) glycation and pigmented accumulation increase markedly during the first 5-10 years of age; (c) the extent of glycation is different in different tissues (in particular, glycation of aortal collagen is about twice that of skin collagen); and (d) ...
Pösö AR, Essén-Gustavsson B, Persson SG.Plasma concentrations of lactate, amino acids, ammonia and products of purine catabolism were studied before, during and after a standardised incremental exercise test in 29 Standardbred trotters admitted to the clinic for exercise tolerance testing. According to their red cell volume the horses were divided into red cell normovolaemic and red cell hypervolaemic (polycythaemic) groups. The exercise-response curve for taurine differed significantly in the two groups, whereas all the other amino acids behaved similarly. The [branched-chain amino acid]/[alanine] ratio, a proposed indicator for th...
Stefaniuk-Szmukier M, Ropka-Molik K, Piórkowska K, Żukowski K, Bugno-Poniewierska M.The impact of exercises on young developing organisms is still of interest to researchers. Similarly like Thoroughbreds, Arabian horses competing at the race track. The high percent of lameness and loss of days in training are often the result of weakness in the condition of the musculoskeletal system. The objective of the presented study was to identify by RNA-Seq method, the possible skeletal system originating transcriptomic profile in peripheral blood of Arabian horses undergoing race training. Obtained results showed that one of the most significantly deregulated pathway involved in bone ...
Seanor JW, Byars TD, Boutcher JK.Renal dysfunction secondary to GI disorders may be relatively common in horses. Persistent dehydration of 8-10% of body weight can lead to prerenal azotemia, which may result in renal ischemia and renal disease if uncorrected. Dehydrated azotemic horses with a urine specific gravity less than 1.018 may have renal disease. Urine specific gravity readings greater than 1.025 usually indicate normal kidney function. A urine Na level less than 20 mEq/L and a urine/plasma creatinine ratio greater than or equal to 20:1 indicate prerenal problems. Use of nephrotoxic drugs should be avoided in septicem...
Krook L, Wasserman RH, Shively JN, Tashjian AH, Brokken TD, Morton JF.A chronic debilitating disease is described in Florida horses. There is progress weight loss and lameness of increasing severity. Plasma calcium is elevated to moderate or severe degree. Anatomical changes include dystrophic calcinosis of elastic tissues, viz. major arteries, tendons and ligaments. A generalized osteopetrosis is present and may be related to hypoparathyroidsim and hypercalcitoninism. The presence of Cestrum diurnum (day-blooming jessamine, day cestrum, wild jasmin) in areas accessible to affected animals, the observation that leaves of the plant were stripped in these areas, a...
Parks CM, Manohar M.Blood-gas tensions and acid-base status were examined in 8 healthy grade ponies at rest (heart rate = 55 +/- 3 beats/min) and during moderate (fast trot; heart rate = 155 +/- 3 beats/min) and severe (gallop; heart rate = 218 +/- 7 beats/min) exercise performed on a treadmill. Arterial oxygen tension and hemoglobin-oxygen saturation of exercising ponies did not change from the resting values. Arterial oxygen content increased markedly during exercise, as a consequence of increased hemoglobin concentration. The total oxygen content, as well as the saturation of hemoglobin with oxygen in the mixe...
McGuire TC.Comparison of immunoglobulin levels of nine horses before and after infection with equine infectious anaemia (EIA) virus demonstrated a significant depression of serum IgG(T) at 2 months (P less than 0-001) and at 1 year (P less than 0-01) after infection. In contrast, the levels of IgGa were significantly increased at both times after infection. Another sixteen horses with EIA for 1-4 months were examined and there was also significant depression (P less than 0-001) of IgG(T) when compared to pre-infection levels. No significant changes in IgG(T), IgGa and IgM were noted in fourteen normal ho...
Kelso TB, Hodgson DR, Visscher AR, Gollnick PD.Several biochemical components of the white portion of the gastrocnemius (WGM), plantaris (PM), and soleus (SM) muscles of the rat and middle gluteal (MGM) muscle of the horse were compared based on wet and dry weight, protein, and total creatine concentrations ([TCr]). The water content was similar for the rat hindlimb muscles, however, the concentrations of protein, ATP, phosphocreatine (PCr), creatine, and glycogen ranked as SM less than PM less than WGM for all reference bases except total creatine. In contrast, concentrations of ATP, creatine, and PCr were similar in all muscles studied w...
