Glucose is a simple sugar that serves as a primary energy source for horses. It is metabolized through various biochemical pathways to support cellular functions and overall energy requirements. In equine physiology, glucose levels are influenced by factors such as diet, exercise, and metabolic health. Monitoring glucose concentrations is important for understanding metabolic conditions, such as insulin resistance and equine metabolic syndrome, which can affect a horse's health and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the regulation, metabolism, and clinical implications of glucose in equine health.
Tóth F, Frank N, Martin-Jiménez T, Elliott SB, Geor RJ, Boston RC.Hyperinsulinaemia is detected in horses with insulin resistance (IR) and has previously been attributed to increased pancreatic insulin secretion. Connecting peptide (C-peptide) can be measured to assess pancreatic function because it is secreted in equimolar amounts with insulin and does not undergo hepatic clearance. Objective: A human double antibody radioimmunoassay (RIA) detects C-peptide in equine serum and concentrations would reflect responses to different stimuli and conditions. Methods: A validation procedure was performed to assess the RIA. Six mature mares were selected and somatos...
Tóth F, Frank N, Geor RJ, Boston RC.To investigate the effects of dexamethasone or levothyroxine sodium on endotoxin-induced alterations in glucose and insulin dynamics. Methods: 24 horses. Methods: Horses were randomly allocated to 3 treatment groups and received 48 mg of levothyroxine mixed with 200 g of oats, 20 mg of dexamethasone plus oats, or oats alone (control) for 15 days, followed by IV infusion of lipopolysaccharide (20 ng/kg) while individually housed in stalls. Frequently sampled IV glucose tolerance tests were performed prior to pretreatment, after pretreatment, and 20 hours after lipopolysaccharide administration....
Suagee JK, Corl BA, Crisman MV, Wearn JG, McCutcheon LJ, Geor RJ.The lipogenic capacities of equine liver and adipose tissue explants were investigated in vitro. Preference for glucose or acetate as the primary carbon source for de novo fatty acid synthesis was determined using (14)C labeled substrates. Additional aims included determining the relative contribution of NADPH generating pathways to reducing equivalent generation and comparing the lipogenic activity of two adipose depots, mesenteric and subcutaneous harvested from the crest region of the neck. Mesenteric adipose tissue had greater lipogenic activity than subcutaneous adipose tissue, and liver ...
Eivers SS, McGivney BA, Fonseca RG, MacHugh DE, Menson K, Park SD, Rivero JL, Taylor CT, Katz LM, Hill EW.Intense selection for elite racing performance in the Thoroughbred horse (Equus caballus) has resulted in a number of adaptive physiological phenotypes relevant to exercise; however, the underlying molecular mechanisms responsible for these characteristics are not well understood. Adaptive changes in mRNA expression in equine skeletal muscle were investigated by real-time qRT-PCR for a panel of candidate exercise-response genes following a standardized incremental-step treadmill exercise test in eight untrained Thoroughbred horses. Biopsy samples were obtained from the gluteus medius before, i...
Carter RA, McCutcheon LJ, George LA, Smith TL, Frank N, Geor RJ.To determine the effects of diet-induced weight gain on glucose and insulin dynamics and plasma hormone and lipid concentrations in horses. Methods: 13 adult geldings. Methods: Horses were fed 200% of their digestible energy requirements for maintenance for 16 weeks to induce weight gain. Frequently sampled IV glucose tolerance tests were performed before and after weight gain to evaluate glucose and insulin dynamics. Adiposity (assessed via condition scoring, morphometric measurements, and subcutaneous fat depth) and plasma concentrations of insulin, glucose, nonesterified fatty acids, trigly...
Hassel DM, Hill AE, Rorabeck RA.Glucose homeostasis is dysregulated in critically ill humans resulting in hyperglycemia and decreased survival. Hyperglycemia is common in horses presenting with abdominal crisis, and this might be associated with a worse prognosis for survival. Objective: To determine if hyperglycemia in horses with acute abdominal disease is associated with increased odds of failure to survive to hospital discharge. Methods: Two hundred and twenty-eight adult horses with acute gastrointestinal disease. Methods: Observational retrospective study. Records of horses > 1 year of age presenting for treatment o...
Vervuert I, Klein S, Coenen M.A standardised methodology is required for classification of starchy diets. One important question is what feeding status is optimal to describe glycaemic and insulinaemic responses to the respective starchy diet. Four horses were fed, in a randomised order, four different feeding protocols relative to offering hay before or after cracked corn (CC): (i) ad libitum hay for 12 h before feeding CC and ad libitum hay after CC intake for 9 h (+CC+), (ii) ad libitum hay for 12 h before feeding CC and no hay after CC intake for 9 h (+CC-), (iii) feed restriction for 12 h before feeding CC and ad libi...
Cehak A, Burmester M, Geburek F, Feige K, Breves G.The aim of this study was to characterize the transport mechanisms of electrolytes and nutrients across the jejunum of nine healthy horses electrophysiologically. The stripped mucosa was mounted in Ussing chambers and tissue conductances (G(t)) and short circuit currents (I(sc)) were continuously monitored. After blocking the sodium and potassium channels with amiloride, tetraethylammonium chloride (TEA) and barium, chloride secretion was stimulated by carbachol and forskolin. Subsequently, chloride channels were inhibited by 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid, 5-nitro-2-(3-ph...
Patan B, Budras KD, Licka TF.To establish an ex vivo model of blood perfusion in the distal portion of isolated equine forelimbs that closely represents the in vivo situation in the laminar tissue of the hoof. Methods: 18 forelimbs collected from 9 healthy adult horses following slaughter at a licensed abattoir. Methods: The distal portion of isolated equine forelimbs from 9 horses were perfused under physiologic conditions over a period of 6, 8, and 10 hours with autologous blood. To determine cell viability in perfused tissues, indicators for metabolism (lactate generation and glucose and oxygen consumption) as well as ...
Kalck KA, Frank N, Elliott SB, Boston RC.To ascertain whether laminitis can be induced via administration of oligofructose (OF) at doses of 5.0 and 7.5 g/kg in horses and to assess glucose and insulin dynamics before and after treatment. Methods: 19 adult horses. Methods: Horses were fed OF (1.0 g/kg) mixed with oats for 6 days. Oligofructose at doses of 5.0 and 7.5 g/kg was then mixed with 4 L of water and administered (0 hours) to 8 (group A) and 4 (group B) horses, respectively, via nasogastric intubation; 8 horses received water alone. One horse in group A that did not develop laminitis was subsequently treated again and included...
George LA, Staniar WB, Treiber KH, Harris PA, Geor RJ.Nutritional management of animals during pregnancy can affect glucose and insulin dynamics in the resulting offspring through influences on fetal development. Additionally, high starch feeding in mature horses is associated with reduced insulin sensitivity and an increased risk for diseases such as obesity and laminitis. However, no study has yet evaluated the effect of feeding a high starch diet to pregnant mares on glucose and insulin dynamics in their offspring. Twenty late-gestation mares maintained on pasture were provided two-thirds of digestible energy requirements from isocaloric, ison...
Harris P, Geor RJ.The feeding of "low carbohydrate" or "low glycemic" diets has been recommended for management of horses with metabolic and endocrine disorders in which insulin resistance is a component. A "low carbohydrate" diet is a misnomer, however, because horses require that a significant proportion of their daily ration comprises structural carbohydrates (fiber/forage) to maintain gut health and mental wellbeing. This article provides a detailed description of the different carbohydrates in equine feeds. It also reviews the terminology used to describe glucose and insulin responses to the ingestion of c...
Duehlmeier R, Hacker A, Widdel-Bigdely A, von Engelhardt W, Sallmann HP.Glucose homeostasis depends on insulin-regulated glucose uptake in the skeletal muscles and fat tissues via glucose transporter (GLUT) 4 translocation into cellular plasma membranes. The present study sought to elucidate GLUT4 expression, GLUT1 and GLUT4 translocation and glucose uptake in the skeletal muscles of Shetland ponies. Semitendinosus muscle explants were removed by open muscle biopsy from six Shetland pony geldings under general anaesthesia. The expression of GLUT4 was analysed by measuring muscle crude membrane (CM) GLUT4 protein contents. To determine the insulin-stimulated GLUT t...
Edner AH, Essén-Gustavsson B, Nyman GC.Muscle metabolism in horses has been studied mainly by analysis of substances in blood or plasma and muscle biopsy specimens. By using microdialysis, real-time monitoring of the metabolic events in local tissue with a minimum of trauma is possible. There is limited information about muscle metabolism in the early recovery period after anaesthesia in horses and especially in the colic horse. The aims were to evaluate the microdialysis technique as a complement to plasma analysis and to study the concentration changes in lactate, pyruvate, glucose, glycerol, and urea during anaesthesia and in th...
Davies JA, Krebs GL, Barnes A, Pant I, McGrath PJ.A feeding trial involving four Thoroughbred race horses was undertaken to establish whether inclusion of grape seed extract (GSE) in the diet of horses undergoing mild exercise had any effects on their general health, intake and digestion. Supplementation with GSE had no effect on either feed or water intake of the horses and the supplement was readily palatable to the horses at all levels of inclusion. Feeding GSE caused no adverse effects in terms of animal health (temperature, pulse and respirations rates), and there were some positive effects related to a presumed alteration in fermentatio...
Vervuert I, Klein S, Coenen M.The aim of this study was to investigate the effects of fat supplementation on postprandial glycaemic and insulinaemic responses in horses fed a corn meal. Four horses were fed three different diets: (1) cracked corn (CC), (2) cracked corn with soybean oil (CC+SBO), and (3) cracked corn with fish oil (CC+FO). Each diet was adjusted so there was a starch intake of 2 g/kg bodyweight (BW) and an intake of 0.2 mL/kg BW of FO and SBO. The increases in mean plasma glucose and insulin concentrations, peak values, and areas under the curve were similar for all diets (time P<0.05, diet not significa...
Ousey JC, Fowden AL, Wilsher S, Allen WR.Chronic and acute alterations in maternal nutrient intake during pregnancy alter pancreatic and hypothalamo-pituitary-adrenal (HPA) axis function in the offspring, before and after birth. Little is known about these effects. Objective: To determine whether maternal nutrient restriction caused by natural infection with Streptococcus equi altered endocrine function in neonatal foals born from mares fed a maintenance or high plane of nutrition throughout pregnancy. Methods: Ten primiparous mares received either a diet to maintain moderate body condition score (Moderate, n = 5) or a near ad libitu...
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...
Ferraz GC, Teixeira-Neto AR, Mataqueiro MI, Lacerda-Neto JC, Queiroz-Neto A.To investigate the effect of acute administration of caffeine on the athletic performance of Arabian horses. Methods: 12 healthy adult Arabian horses that were trained for exercise on a treadmill. Methods: By use of a crossover study design, horses received each of the following treatments: IV administration of caffeine (5 mg/kg) and IV administration of approximately the same volume of saline (0.9% NaCl) solution. Order of treatment was randomized, and there was a 10-day interval between treatments. Thirty minutes after treatments, horses underwent an incremental exercise test (IET) on a trea...
Dyer J, Al-Rammahi M, Waterfall L, Salmon KS, Geor RJ, Bouré L, Edwards GB, Proudman CJ, Shirazi-Beechey SP.Experimental and epidemiological evidence suggests that consumption of hydrolyzable carbohydrate, hCHO (grain), by horses is an important risk factor for colic, a common cause of equine mortality. It is unknown whether the small intestinal capacity to digest hCHO and/or to absorb monosaccharides is limiting, or even if horses can adapt to increased carbohydrate load. We investigated changes in the brush-border membrane carbohydrate digestive enzymes and glucose absorptive capacity of horse small intestine in response to increased hCHO. Expression of the Na(+)/glucose co-transporter, SGLT1, was...
Vervuert I, Klein S, Coenen M.The aim of this study was to investigate the effect of the addition of a purified soluble (pectin) and insoluble (lignocellulose) fibre to a starchy meal on post-prandial glucose and insulin responses in healthy horses. Four horses were fed in a randomized order three different diets: (i) cracked corn, (ii) cracked corn mixed with purified lignocellulose, and (iii) cracked corn mixed with purified pectin. Each diet was adjusted to a starch intake of 2 g/kg bodyweight (BW). Lignocellulose was aligned to an intake of 0.2 g/kg BW, and pectin was fed in a dosage of 0.1 g/kg BW. Each period consist...
Haffner JC, Eiler H, Hoffman RM, Fecteau KA, Oliver JW.Sustained dexamethasone administration to horses results in insulin resistance, which may predispose them to laminitis. A single dose of dexamethasone is commonly used as a diagnostic aid, yet the effect of a single dose of dexamethasone on glucose homeostasis in horses is not well defined. The objective of this study was to characterize the change in glucose dynamics over time in response to a single dose of dexamethasone. A combined glucose-insulin tolerance test (CGIT) was performed on 6 adult geldings before and at 2, 24, and 72 h postdexamethasone (40 microg/kg of BW, i.v.); a minimum of ...
Hollis AR, Furr MO, Magdesian KG, Axon JE, Ludlow V, Boston RC, Corley KT.Critical illness is associated with hyperglycemia in humans, and a greater degree and duration of hyperglycemia is associated with nonsurvival. Hypoglycemia is also seen in critically ill humans, and is associated with nonsurvival. This might also be true in the critically ill foal. Objective: To investigate the association of blood glucose concentrations with survival, sepsis, and the systemic inflammatory response syndrome (SIRS). Methods: Blood glucose concentrations at admission (515 foals) and 24 hours (159 foals), 36 hours (95), 48 hours (82), and 60 hours (45) after admission were analy...
Hollis AR, Dallap Schaer BL, Boston RC, Wilkins PA.More information is needed regarding accuracy of commonly used methods of glucose measurement in the critically ill horse. Objective: Glucometry will have good agreement with a laboratory standard. Glucometry with plasma will have better agreement than when performed with whole blood. Methods: Fifty sequentially admitted equine emergency patients, aged >1year. Methods: Venous blood was collected at admission and immediately analyzed by point-of-care glucometry on both whole blood (POC/WB) and plasma (POC/PL), a multielectrode blood gas analyzer with whole blood (BLG), and a standard laborat...
Vervuert I, Voigt K, Hollands T, Cí·¯ord D, Coenen M.The aim of this study was to investigate the effect of increasing the intake of starch on the glycaemic and insulinaemic responses of horses. A cross-over study design was used in which four horses were fed increasing amounts of a compound feed (0.5-3.5 kg) to provide 0.3, 0.6, 0.8, 1.1, 1.4 and 2 starch/kg bodyweight (BW)/meal. The glycaemic response increased with starch intake (P<0.05), while feeding <1.1 g starch/kg BW resulted in a lowered response, compared to when 1.1-2 g starch/ kg BW was fed (P<0.01). The results suggested that insulin responses may be more appropriate to def...
Vervuert I, Voigt K, Hollands T, Cí·¯ord D, Coenen M.Four horses were randomly fed a diet containing rolled, micronised or extruded barley; the barley intake was adjusted to supply 2 g starch/kg bodyweight per day. During a 10-day acclimatisation period the horses were also fed 1 kg grass hay/100 kg bodyweight per day. Samples of blood and breath were collected at the end of each period after the test meal of barley had been fed after a 12-hour overnight fast. The glycaemic and insulinaemic responses of the horses were measured as an indication of the pre-caecal digestibility of starch, and postprandial breath hydrogen and methane were measured ...
Winkelsett S, Vervuert I.Laminitis is a systemic disease which is manifested as a non infectious condition in the foot. The management of feeding and housing conditions is necessary to treat the endocrinological and metabolic disturbances of laminitic horses. The Equine Metabolic Syndrome (EMS) is predisposing for developing laminitis, and it is characterised by obesity, insulin resistance, hypertension and dyslipidaemia. A genetical predisposition is supposed and EMS is accompanied by a lack of exercise and inadequate energy intake. Laboratory examinations are of great importance for diagnosis. Analyses of insulin, g...
Myers CJ, Magdesian KG, Kass PH, Madigan JE, Rhodes DM, Marks SL.This retrospective study describes the use of and complications associated with parenteral nutrition (PN) administration to 53 equine neonates at the University of California Veterinary Medical Teaching Hospital. Medical records were examined and information obtained on signalment, physical examination, clinical diagnosis, outcome, total hospitalization time, insulin administration, microbiology culture results, other complications (i.e. thrombophlebitis) and necropsy findings. Complete blood count and serum biochemistry analytes, venous blood gas, serum electrolyte and glucose concentrations,...
Lindåse S, Nostell K, Söder J, Bröjer J.A hyperbolic relationship between β-cell response and insulin sensitivity (IS) has been described in several species including rodents, dogs, and humans. This relationship has not been elucidated in the horse. Objective: To determine whether the hyperbolic relationship between β-cell response and IS exists in horses by using indices of β-cell response from the oral sugar test (OST) and IS measurements from the euglycemic hyperinsulinemic clamp (EHC). A second aim was to compare how well IS estimates from the OST and EHC correlate. Methods: Forty-nine horses with different degrees of insulin...
Durham AE.Five ponies and one donkey with hyperlipaemia that occurred secondarily to a variety of primary clinical conditions were treated with lipid-free partial parenteral nutrition comprising equal volumes of 50 per cent glucose and 15 per cent amino acids. The infusion supplied energy and protein at rates of 2.6 kJ/kg per hour and 34.3 mg/kg per hour, respectively. In all six cases there was a prompt and sustained decrease in serum concentrations of triglyceride. In four of the six cases a good response to treatment of the primary condition was also seen and the subjects were discharged successfully...
Gentry LR, Thompson DL, Gentry GT, Davis KA, Godke RA.Mares that had previously been fed to attain body condition scores (BCS) of 7.5 to 8.5 (high) or 3.0 to 3.5 (low) were used to determine the interaction of BCS with the responses to 1) administration of equine somatotropin (eST) daily for 14 d beginning January 20 followed by administration of GnRH analog (GnRHa) daily for 21 d and 2) 4-d treatment with dexamethasone later in the spring when mares in low BCS had begun to ovulate. The majority of mares with high BCS continued to cycle throughout the winter, as evidenced by larger ovaries (P < 0.002), more corpora lutea (P < 0.05), greater proge...
Tadros EM, Frank N, De Witte FG, Boston RC.To test the hypothesis that glucose and insulin dynamics during endotoxemia differ between healthy horses and horses with equine metabolic syndrome (EMS). Methods: 6 healthy adult mares and 6 horses with EMS. Methods: Each horse randomly received an IV infusion of lipopolysaccharide (20 ng/kg [in 60 mL of sterile saline {0.9% NaCl} solution]) or saline solution, followed by the other treatment after a 7-day washout period. Baseline insulin-modified frequently sampled IV glucose tolerance tests were performed 27 hours before and then repeated at 0.5 and 21 hours after infusion. Results were ass...
Brunner J, Liesegang A, Weiss S, Wichert B.The aim of this study was to compare the nutritional management of show jumping horses in practice with recommendations from the literature. Additionally, the effects of these feeding practices on several blood metabolic parameters before and after exercise were studied. Blood samples were collected in the field from 27 different horses at 71 trials on the level M1 to S2 show jumping competitions in Switzerland and questionnaires on feeding practice of the studied horses were evaluated. The questionnaires revealed that during training and on tournament days horses received on average 3.1 kg o...
Moore BR, Abood SK, Hinchcliff KW.The medical records from 9 consecutive miniature horses (n = 5) and miniature donkeys (n = 4) with hyperlipemia (serum triglyceride concentration > 500 mg/dL) were reviewed. In all cases, hyperlipemia was a secondary complication of a primary systemic disease including septicemia, colitis, parasitism, esophageal obstruction, gastric impaction and rupture, fecalith, and pituitary adenoma. Therapy consisted of specific treatment for the primary disease, supportive care, and nutritional support. The mean time for resolution of hyperlipemia in cases requiring nutritional support (n = 6) was 7 days...
Taylor PM.Information on the equine stress response to anaesthesia and surgery is sparse but offers a promising approach to elucidating the high anaesthetic risk in this species. Previous work has shown that halothane anaesthesia induces substantial metabolic and endocrine changes. This paper reports the effects of barbiturate anaesthesia. Anaesthesia was induced with thiopentone in six ponies and no further agents were given. They stood within 30 mins. On another occasion, these animals, and three further ponies, were anaesthetised with pentobarbitone and anaesthesia was maintained for 2 h. No surgery ...
Legere RM, Taylor DR, Davis JL, Bello K, Parker C, Judd RL, Wooldridge AA.Chronic insulin dysregulation is challenging to manage with pharmaceuticals in horses. Pioglitazone improves insulin sensitivity in humans, and the pharmacokinetics of pioglitazone have been evaluated in horses. The objectives of this study were to assess the pharmacodynamic effects of oral pioglitazone on morphometric parameters, hepatic enzyme activity and function, adipokines, and enteroinsular response to oral sugar. A prospective pilot study was performed using fifteen adult equids (8 ponies, 7 horses) to evaluate the effects of short-term pioglitazone administration (2 mg/kg PO q 24 hou...
Ropp JK, Raub RH, Minton JE.Feeding diets high in soluble carbohydrates to growing horses has been implicated in the development of orthopedic diseases; as a result, substitution of dietary fat for soluble carbohydrates has received attention. Because IGF-I is integral to growth and cartilage development and because it is influenced by nutrition, we evaluated the effect of dietary fat substitution on metabolic endpoints and circulating GH and IGF-I in growing horses. Twelve Quarter Horse weanlings, four female and eight male, 151 to 226 d old, were blocked by sex and age and assigned to two treatment groups. Group one (C...
Simmons HA, Ford EJ.The production of propionate has been measured in the large colon of two ponies fitted with cannulas and fed on a standard diet of hay or hay and wheat bran. A continuous infusion of 14C-labelled sodium propionate was made into a cannula in the right ventral colon and samples of ingesta were obtained from another cannula near the end of the right dorsal colon. A simultaneous intravenous infusion of [2-3H]-labelled glucose was made to measure total glucose entry. Colonic propionate production on the hay diet was 146 (range 110-176) mg/h per kg body weight and, on the hay and bran, 195 (range 13...
Geor RJ, Hinchcliff KW, Sams RA.To examine the role of beta-adrenergic mechanisms in the regulation of endogenous glucose (Glu) production [rate of appearance (R(a))] and utilization [rate of disappearance (R(d))] and carbohydrate (CHO) metabolism, six horses completed consecutive 30-min bouts of exercise at approximately 30% (Lo) and approximately 60% (Hi) of estimated maximum O(2) uptake with (P) and without (C) prior administration of the beta-blocker propranolol (0.22 mg/kg iv). All horses completed exercise in C; exercise duration in P was 49.9 +/- 1.2 (SE) min. Plasma Glu was unchanged in C during Lo but increased prog...
Bradbery AN, Coverdale JA, Hammer CJ, Dunlap KA, Leatherwood JL, Satterfield MC.Skeletal muscle plays an integral role in the ability of a horse to perform at high levels. Shifts in skeletal muscle development in response to maternal plane of nutrition may have substantial and lasting impacts on athletic performance and whole-body metabolism. Therefore, sixteen Quarter Horse mares were used in a completely randomized design and maintained at a body condition score (BCS) 6 until start of third trimester. On d 235 of gestation, mares were randomly assigned to receive one of two dietary treatments with a diet formulated to meet requirements during late gestation (CON; n = ...
Hicks GR, Fraser NS, Bertin FR.Although there are many hormonal changes associated with reproduction, the effects of ovulation and early pregnancy on adrenocorticotropic hormone (ACTH) and insulin concentrations are poorly described. We hypothesise that both ovulation and early pregnancy will alter ACTH and insulin concentrations in healthy mares. Eighteen mares showing no clinical signs suggestive of, or laboratory findings consistent with, pituitary pars intermedia dysfunction PPID and insulin dysregulation (ID) are enrolled. ACTH, cortisol, insulin and glucose concentrations are measured over their peri-ovulatory period,...
Dorneles TEA, Costa Junior JD, Almeida RM, Teixeira Neto AR.Anaerobic cellular metabolism causes a series of structural and physiologic changes during storage that could compromise post-transfusion viability, reducing the safety of using blood stored for an extended period. Objective: We aimed to follow the biochemical and hematologic alterations of equine blood stored in plastic bags containing citrate-phosphate-dextrose-adenine (CPDA-1) for up to 28 days. Methods: Whole blood samples (450 mL) were collected from 20 Brazilian Saddle horses into CPDA-1 pouches and stored between 2°C and 6°C in a blood bank. On days 0, 7, 14, 21, and 28 of storage, ...
Geor RJ, Hinchcliff KW, McCutcheon LJ, Sams RA.This study examined the effects of preexercise glucose administration, with and without epinephrine infusion, on carbohydrate metabolism in horses during exercise. Six horses completed 60 min of treadmill exercise at 55 +/- 1% maximum O(2) uptake 1) 1 h after oral administration of glucose (2 g/kg; G trial); 2) 1 h after oral glucose and with an intravenous infusion of epinephrine (0.2 micromol. kg(-1). min(-1); GE trial) during exercise, and 3) 1 h after water only (F trial). Glucose administration (G and GE) caused hyperinsulinemia and hyperglycemia ( approximately 8 mM). In GE, plasma epine...
Art T, Desmecht D, Amory H, Delogne O, Buchet M, Leroy P, Lekeux P.The variability of the post-exercise values (PEV) of blood lactate and of some other blood constituents were studied in 8 healthy and fit jumpers through 5 national competitions of equal difficulty. The effects of factors such as the individual, performance and competition on these PEV were analysed. Venous blood was sampled immediately after the 5 show-jumping contests and was analysed for packed cell volume (PCV), blood lactate, blood glucose (GLU), total plasma protein (TPP), bicarbonate (HCO3-), sodium (Na+), potassium (K+), chloride (Cl-), calcium (Ca2+), serum activities of lactate dehyd...
Medina-Torres CE, Pollitt CC, Underwood C, Castro-Olivera EM, Collins SN, Allavena RE, Richardson DW, van Eps AW.Failure of lamellar energy metabolism may contribute to the pathophysiology of equine laminitis. Tissue microdialysis has the potential to dynamically monitor lamellar energy balance over time. The objectives of this study were to develop a minimally invasive lamellar microdialysis technique and use it to measure normal lamellar energy metabolite concentrations over 24 h. Microdialysis probes were placed (through the white line) into either the lamellar dermis (LAM) (n = 6) or the sublamellar dermis (SUBLAM) (n = 6) and perfused continuously over a 24 h study period. Probes were pl...
Annandale EJ, Valberg SJ, Essen-Gustavsson B.To determine whether disruption of adenine triphosphate (ATP) regeneration and subsequent adenine nucleotide degradation are potential mechanisms for rhabdomyolysis in horses with polysaccharide storage myopathy (PSSM) performing submaximal exercise. Methods: 7 horses with PSSM and 4 control horses. Methods: Horses with PSSM performed 2-minute intervals of a walk and trot exercise on a treadmill until muscle cramping developed. Control horses exercised similarly for 20 minutes. Serum creatine kinase (CK) activity was measured 4 hours after exercise. Citrate synthase (CS), 3-OH-acylCoA dehydrog...
Silver M, Fowden AL.In the present study, ten insulin challenge tests were carried out on nine chronically catheterized fetal foals between 253 and 314 days gestation (term > 320 days). Changes in fetal plasma concentrations of glucose, catecholamines, cortisol, ACTH, free fatty acid (FFA) and lactate were measured before and after a bolus dose of insulin (0.5-2.0 u/kg I.V.). Fetal blood gases, pH, haemoglobin levels and heart rate were measured throughout the 2-3h experimental period. The fetuses fell into two distinct groups on the basis of proximity to delivery and basal plasma cortisol and catecholamine level...
Flisińska-Bojanowska A, Gill J, Komosa M, Kompanowska-Jezierska E.1. In six standard-bred mares and their foals diurnal changes in the cortisol and glucose levels and in FDPA activity were studies for 13 weeks of foal life. 2. In the cortisol level diurnal rhythm was found in the 3rd, 7th and 11th week of foal life and in the 11th week of lactation in mares. 3. In mares the mean diurnal cortisol level changed from 32 ng/ml in the first week to 57 in the 11th week and in foals from 24 in the first week to 16 ng/ml in the 11th week. 4. In the glucose level no diurnal rhythm was observed. 5. In mares the mean diurnal glucose level after parturition was about 58...
Schwarz B, Ertl R, Zimmer S, Netzmann Y, Klein D, Schwendenwein I, Hoven RV.The aim of this study was to determine the occurrence and frequency of a mutation in the gene coding for skeletal muscle glycogen synthase type 1 (GYS-1), which is the cause of equine polysaccharide storage myopathy (PSSM) type 1 in a population of 50 Haflingers. GYS-1 genotyping of 50 Haflingers was performed with a validated restriction fragment length polymorphism (RFLP) assay. The second aim was to compare resting and post-exercise muscle enzyme activities as well as parameters of glucose metabolism in blood between horses with and without the mutation. Nine of the 50 Haflingers were ident...
Medina-Torres CE, Underwood C, Pollitt CC, Castro-Olivera EM, Hodson MP, Richardson DW, van Eps AW.Lamellar perfusion is thought to be affected by weightbearing and limb load cycling; this may be critical in the development of supporting limb laminitis. Objective: To document the effects of unilateral weightbearing and altered limb load cycling on lamellar energy metabolism and perfusion. Methods: Randomised, controlled (within subject), experimental trial. Methods: Nine Standardbred horses were instrumented with microdialysis probes in the foot lamellar tissue and skin (over the tail base). Urea (20 mmol/l) was added to the perfusate. Samples were collected every 15 min for a 1 h con...
Fujiyama M, Jones T, Duke-Novakovski T.To evaluate perioperative stress-related hormones in isoflurane-anesthetized horses administered infusions of dexmedetomidine alone or with butorphanol or remifentanil, compared with ketamine-morphine. Methods: Randomized, prospective, nonblinded clinical study. Methods: A total of 51 horses undergoing elective surgical procedures. Methods: Horses were premedicated with xylazine, anesthesia induced with ketamine-diazepam and maintained with isoflurane and one of four intravenous infusions. Partial intravenous anesthesia (PIVA) was achieved with dexmedetomidine (1.0 μg kg hour; group D; 12 hor...
Freeman DE.Accumulation of D-xylose by jejunal mucosa from healthy horses and rabbits was studied in vitro. When tissue sheets were incubated with 1 mM D-xylose for 60 minutes, mucosa from horses and rabbits accumulated D-xylose against a concentration gradient. There was no accumulation when equine specimens were incubated with 5 mM D-xylose. By comparison, equine jejunum accumulated D-glucose against a concentration gradient when incubated in 5 mM D-glucose. In equine and rabbit jejunum, 13.3 +/- 7.0% and 36 +/- 11.0%, respectively, of accumulated D-xylose was phosphorylated when sheets were incubated ...
De La Corte FD, Valberg SJ, MacLeay JM, Williamson SE, Mickelson JR.To determine whether excessive glycogen accumulation in skeletal muscle of Quarter Horses with polysaccharide storage myopathy (PSSM) is a result of enhanced cellular uptake of glucose. Methods: 6 horses with PSSM and 10 healthy (control) horses. Methods: Intravenous glucose tolerance tests (IVGTT), oral glucose tolerance tests (OGTT), and modified insulin tolerance tests (MITT) were performed. Plasma glucose and insulin concentrations were measured in blood samples collected before and for up to 8 hours after glucose or insulin administration. Results: Peak glucose concentrations during IVGTT...
Cartmill JA, Thompson DL, Gentry LR, Pruett HE, Johnson CA.In experiment 1, nine light horse geldings (three 3 x 3 Latin squares) received dexamethasone (DEX; 125 microg/kg BW, i.m.), glucose (0.2 g/kg BW, i.v.), or nothing (control) once per day for 4 days. DEX increased (P < 0.001) glucose, insulin, and leptin concentrations and resulted in a delayed increase (P < 0.001) in IGF-I concentrations. In experiment 2, mares were similarly treated with DEX (n = 6) or vehicle (n = 6). DEX again increased (P < 0.01) glucose, insulin, and leptin concentrations; the delayed elevation in IGF-I concentrations occurred on day 10, 12, and 19, relative to ...
Vervuert I, Coenen M, Bothe C.This study was conducted to evaluate the effects of different oat processing techniques on the plasma glucose and insulin response in horses. In a cross-over design, six horses (ages 4-15 years, mean body weight+/-SD: 450+/-37 kg) were fed in random order: untreated oats, finely ground, steam-flaked and popped oats. The total oat intake varied between 1.05-1.5 kg/day, and the amount of diet was adjusted to a starch content of 630 g starch per day and horse (1.2-1.5 g starch/kg BW/day). During the stabilization period of 10 days, horses additionally received 6 kg grass hay. Following this adapt...
Matsui A, Ohmura H, Asai Y, Takahashi T, Hiraga A, Okamura K, Tokimura H, Sugino T, Obitsu T, Taniguchi K.In man, muscle protein synthesis is accelerated by administering amino acids (AA) and glucose (Glu), because increased availability of amino acids and increased insulin secretion, is known to have a protein anabolic effect. However, in the horse, the effect on muscle hypertrophy of such nutrition management following exercise is unknown. Objective: To determine the effect of AA and Glu administration following exercise on muscle protein turnover in horses. We hypothesise that administration of AA and Glu after exercise effects muscle hypertrophy in horses, as already shown in man and other ani...
Frank N, Andrews FM, Elliott SB, Lew J, Boston RC.Plasma lipid concentrations, lipoprotein composition, and glucose dynamics were measured and compared between mares fed diets containing added water, corn oil (CO), refined rice bran oil (RR), or crude rice bran oil (CR) to test the hypothesis that rice bran oil lowers plasma lipid concentrations, alters lipoprotein composition, and improves insulin sensitivity in mares. Eight healthy adult mares received a basal diet fed at 1.5 times the DE requirement for maintenance and each of the four treatments according to a repeated 4 x 4 Latin square design consisting of four 5-wk feeding periods. Blo...
Vervuert I, Klein S, Coenen M.A standardised methodology is required for classification of starchy diets. One important question is what feeding status is optimal to describe glycaemic and insulinaemic responses to the respective starchy diet. Four horses were fed, in a randomised order, four different feeding protocols relative to offering hay before or after cracked corn (CC): (i) ad libitum hay for 12 h before feeding CC and ad libitum hay after CC intake for 9 h (+CC+), (ii) ad libitum hay for 12 h before feeding CC and no hay after CC intake for 9 h (+CC-), (iii) feed restriction for 12 h before feeding CC and ad libi...
