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.
Taylor EA, Beard WL, Douthit T, Pohlman L.Caecal acidosis is a central event in the metabolic cascade that occurs following grain overload. Buffering the caecal acidosis by enterally administered sodium bicarbonate (NaHCO3 ) may be beneficial to affected horses. Objective: To determine the effect and duration of enterally administered NaHCO3 on caecal pH in healthy horses. Methods: Experimental study using horses with caecal cannulas. Methods: Nine horses had been previously fitted with a caecal cannula. Six horses received 1.0 g/kg bwt NaHCO3 and 3 control horses were given 3 l of water via nasogastric tube. Clinical parameters, ...
Rendle DI, Litchfield E, Heller J, Hughes KJ.There is little published information on whether measurement of plasma ACTH concentration at a single timepoint is a repeatable indicator of pituitary pars intermedia dysfunction (PPID). Objective: To determine whether ultradian or circadian fluctuations in ACTH production influence plasma ACTH concentration in normal horses and horses with PPID. Methods: Prospective observational study. Methods: Plasma ACTH concentration in 8 non-PPID horses and 8 horses with PPID was measured at 08.00, 11.00, 14.00 and 17.00 h on 5 nonconsecutive days within a 3 week period. In addition, at 08.30 h on one da...
Bröjer J, Lindåse S, Hedenskog J, Alvarsson K, Nostell K.The increasing number of horses diagnosed with insulin resistance (IR) and the suggested link between IR and laminitis has highlighted the need to accurately diagnose IR in clinical practice. Objective: The aim of the study was to evaluate the repeatability of the combined glucose-insulin tolerance test (CGIT) as well as to determine the effect of 2 different breeds and the effect of a stressor on the test results. Methods: Clinically normal horses, 9 Standardbred horses and 9 Icelandic horses. Methods: Prospective clinical nonrandomized trial. The CGIT was performed on all horses on 2 occasio...
Yi R, Zhao S, Lam G, Sandhu J, Loganathan D, Morrissey B.Cathinone is the principal psychostimulant present in the leaves of khat shrub, which are widely used in East Africa and the Arab peninsula as an amphetamine-like stimulant. Cathinone readily undergoes metabolism in vivo to form less potent cathine and norephedrine as the metabolites. However, the presence of cathine and norephedrine in biological fluids cannot be used as an indicator of cathinone administration. The metabolism of pseudoephedrine and ephedrine, commonly used in cold and allergy medications, also produces cathine and norephedrine, respectively, as the metabolites. Besides, cath...
Gordon ME, Edwards MS, Sweeney CR, Jerina ML.The objective of this study was to test the hypothesis that an equine diet formulated with chelated trace minerals, organic selenium, yeast culture, direct-fed microbials (DFM) and Yucca schidigera extract would decrease excretion of nutrients that have potential for environmental impact. Horses were acclimated to 100% pelleted diets formulated with (ADD) and without (CTRL) the aforementioned additives. Chelated sources of Cu, Zn, Mn, and Co were included in the ADD diet at a 100% replacement rate of sulfate forms used in the CTRL diet. Additionally, the ADD diet included organic selenium yeas...
Miranda MC, Queiroz-Neto A, Silva-Júnior JR, Pereira MC, Soares OA, Borghi RT, Ferraz GC.To compare five different protocols for estimating the lactate minimum speed (LMS) with that for estimating the maximal lactate steady state (MLSS) in Arabian horses, in order to obtain a more rapid method for monitoring aerobic capacity and prescribing training schedules. Methods: Eight purebred Arabian horses were conditioned to exercise on a treadmill for 12 days then submitted to three to five exercise sessions to determine the MLSS. Blood samples were collected from a jugular catheter at specific intervals for measurement of lactate concentrations. The MLSS was the velocity maintained dur...
Hortensius RA, Harley BA.The design of biomaterials for regenerative medicine can require biomolecular cues such as growth factors to induce a desired cell activity. Signal molecules are often incorporated into the biomaterial in either freely-diffusible or covalently-bound forms. However, biomolecular environments in vivo are often complex and dynamic. Notably, glycosaminoglycans (GAGs), linear polysaccharides found in the extracellular matrix, are involved in transient sequestration of growth factors via charge interactions. Biomaterials mimicking this phenomenon may offer the potential to amplify local biomolecular...
Knowles EJ, Menzies-Gow NJ, Mair TS.Plasma fructosamine concentration ([fructosamine]) is believed to reflect medium term, average blood glucose concentration and in a previous study was higher in horses with active laminitis than in normal horses. Pituitary pars intermedia dysfunction (PPID) is associated with hyperglycaemia and laminitis. Objective: To test the hypotheses that: [fructosamine] is higher in PPID cases than normal animals; furthermore, that within cases of PPID [fructosamine] is higher in those with active laminitis than nonlaminitic cases and in cases that have been affected by active laminitis in the preceding ...
The Journal of physiologyJuly 1, 2013
Volume 591, Issue 18 4499-4513 doi: 10.1113/jphysiol.2013.257956
Vengust M, Staempfli H, Viel L, Swenson ER, Heigenhauser G. During intense exercise in horses the transvascular fluid flux in the pulmonary circulation (Jv-a) represents 4% of cardiac output (Q). This fluid flux has been attributed to an increase in pulmonary transmural hydrostatic forces, increases in perfused microvascular surface area, and reversible alterations in capillary permeability under conditions of high flow and pressure. Erythrocyte fluid efflux, however, accounts for a significant fraction of Jv-a. In the lung the Jacobs-Stewart cycle occurs with diffusion of CO2 into alveolar space with possible accompanying chloride (Cl-) and water ...
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...
Barsnick RJ, Hurcombe SD, Dembek K, Frazer ML, Slovis NM, Saville WJ, Toribio RE.Resistance to the somatotropic axis and increases in ghrelin concentrations have been documented in critically ill human patients, but limited information exists in healthy or sick foals. Objective: To investigate components of the somatotropic axis (ghrelin, growth hormone and insulin-like growth factor-1 [IGF-1]) with regard to energy metabolism (glucose and triglycerides), severity of disease and survival in critically ill equine neonates. It was hypothesised that ghrelin and growth hormone would increase and IGF-1 would decrease in proportion to severity of disease, supporting somatotropic...
Kutzner-Mulligan J, Eisemann J, Siciliano P, Smith J, Hewitt K, Sharlette J, Pratt-Phillips S.Management techniques that reduce the insulin response to feeding in horses have application in preventing insulin resistance (IR) and potential associations (e.g., laminitis). Eight mature idle horses of BCS between 5 and 6.5 and with no previous indication of IR were fed a meal of concentrate under 4 feed delivery treatments in a repeated Latin Square design. Treatments were all based on a bucket of equal dimensions. The treatments included a control (CON) and 3 treatments hypothesized to increase time to consume feed (TCF): mobile obstacles above the feed (BALL), stationary obstacles below ...
Brinkmann L, Gerken M, Riek A.Water is an essential nutrient necessary to support life, and adequate water supply is crucial for animal survival and productivity. The present study was designed to determine seasonal changes in the water metabolism of horses under outdoor conditions. Total body water (TBW) and total water intake (TWI) of 10 adult Shetland pony mares were estimated at monthly intervals for 14 mo by using the deuterium dilution technique. During the last 4 mo, 5 ponies were fed restrictively to simulate natural feed shortage in winter, and 5 ponies served as controls. The TBW (kg) was closely related to body ...
Wagner AL, Urschel KL, Lefta M, Esser KA.To determine the effect of biopsy collection depth on the postprandial activation of mammalian target of rapamycin (mTOR) signaling factors, particularly protein kinase B, ribosomal protein S6 kinase, ribosomal protein S6, and eukaryotic initiation factor 4E binding protein 1 in middle-aged horses. Methods: 6 healthy Thoroughbred mares (mean ± SD age, 13.4 ± 3.4 years). Methods: Horses were fed a high-protein feed at 3 g/kg. Sixty minutes after horses were fed, the percutaneous needle biopsy technique was used to collect biopsy specimens from the gluteus medius muscle at 6, 8, and 10 cm belo...
Lees P, Toutain PL.The presence of horse meat in food products destined for human consumption and labelled as beef has raised several concerns of public interest. This review deals solely with one aspect of these concerns; samples of equine tissue from horses destined for the human food chain have tested positive for the non-steroidal anti-inflammatory drug, phenylbutazone. The safety of some or all such foods for human consumers is a major concern, because it was shown many years ago that phenylbutazone therapy in humans can be associated with life threatening blood dyscrasias. As an initial basis for assessing...
Bohák Z, Szabó F, Beckers JF, Melo de Sousa N, Kutasi O, Nagy K, Szenci O.Daily fluctuations of cortisol concentration in the blood or saliva have been repeatedly reported. However, several contradictions in the existing literature appear on this subject. The present study was performed to definitively establish options for testing adrenocortical function. To the best of our knowledge, this is the first study to evaluate parallel circadian rhythms in salivary and serum cortisol concentrations during a 24-h period. Twenty horses were examined under the same conditions. Blood and saliva samples were taken every 2 h for 24 h to determine the daily changes in cortisol c...
Bohar Topolovec M, Kruljc P, Prošek M, Jazbec Križman P, Smidovnik A, Nemec Svete A.Coenzyme Q10 (CoQ10) is an essential cofactor in the mitochondrial electron transport pathway, and is also the only known endogenously synthesized lipid-soluble antioxidant. The aim of the present study was to determine, for the first time, endogenous plasma CoQ10 concentration and its correlation with plasma total antioxidant capacity (TAC) and serum total cholesterol (TC) in a population of healthy untrained horses. Thirty-one horses were included in the study. Plasma CoQ10 concentration ranged from 0.380 to 2.090 mg/L, which is in general agreement with plasma CoQ10 concentration in humans....
Morlière P, Mazière JC, Patterson LK, Conte MA, Dupas JL, Ducroix JP, Filipe P, Santus R.Ferritin (Ft) impairment through (•)O2(-), H2O2, and (•)OH production occurs in the cases of ketoses, diabetes mellitus, acute intermittent porphyria and tyrosinemia. In addition to (•)Trp and TyrO(•) radical production, ferrous iron liberation and Ft synthesis stimulation, site-specific oxidation reactions are induced leading to toxic iron accumulation in organs with high Ft content, for example, liver and brain. To elucidate the potential pathways to Ft recovery, repair of oxidative damage to horse spleen apoferritin (apoFt) and Ft by quercetin (QH) or rutin (RH) was studied in the p...
Hayami A, Darwish WS, Ikenaka Y, Nakayama SM, Ishizuka M.There is little information about drug metabolism and pharmacokinetics in horses. Therefore, it is necessary to characterize the profiles of drug metabolites for the safe use of drugs. In this study, we focused on cytochrome P450 enzymes (CYPs), which represent an important enzyme group to determine pharmacological effects of drugs. We chose diazepam as the drug of choice for this study. The aim of this study was to elucidate the metabolic pathway of diazepam in horses in comparison with rats, and to clarify CYP subfamilies responsible for diazepam metabolism in horses. Our results showed tema...
Carlson ER, Stewart AA, Carlson KL, Durgam SS, Pondenis HC.To compare the effects of autologous equine serum (AES) and autologous conditioned serum (ACS) on equine articular chondrocyte metabolism when stimulated with recombinant human (rh) interleukin (IL)-1β. Methods: Articular cartilage and nonconditioned and conditioned serum from 6 young adult horses. Methods: Cartilage samples were digested, and chondrocytes were isolated and formed into pellets. Chondrocyte pellets were treated with each of the following: 10% AES, 10% AES and rhIL-1β, 20% AES and rhIL-1β, 10% ACS and rhIL-1β, and 20% ACS and rhIL-1β, and various effects of these treatments...
Lorenzo JM, Pateiro M.The effect of fat content on physico-chemical properties and lipid and protein stability of foal liver pâté was studied. For this purpose, two batches (10 units per batch) of foal liver pâté with different pork back fat content [30% (30F) and 40% (40F)] were manufactured. 30F foal liver pâté was darker (lower L* value, P>0.05), redder (higher a*, P<0.001) and harder (higher hardness value; P<0.001) compared to those with 40F. Fat level was closely related to the calorific value of foal liver pâté, being more calorific in those with higher fat contents (352 kcal/100 g; P<0.001). Regardi...
Peters LW, Smiet E, de Sain-van der Velden MG, van der Kolk JH.In particular branched-chain amino acids might limit muscle protein loss in pathological conditions. Little is known on basic amino acid utilization of muscle in horses. Objective: To assess amino acid utilization by the hindlimb of horses at rest and following low intensity exercise. ANIMALS & METHODS: Amino acid uptake by the hindlimb was investigated using the arteriovenous difference technique. Blood from six warmblood mares (mean age 12 ± 3 (SD) years and weighing 538 ± 39 kg) was collected simultaneously from the (transverse) facial artery and from the caudal vena cava. Food was wi...
Vacchina V, Ionescu C, Oguey S, Lobinski R.A method was developed for the quantification of Zn-, Cu- and Mn-glycinates in supplemented feed samples. The coupling of capillary electrophoresis (CE) with ICP MS detection after purification of the extract by ultrafiltration was shown to be efficient for the quantitative recovery of glycinates. The method developed was then applied to evaluate the bioaccessibility of glycinates using a sequential enzymolysis approach. The data obtained indicated a strong bioaccessibility of each element (79-94%). A new complex was also found to be formed during the digestion process. Bioavailability was the...
Capolongo F, Gallina G, Fidani M, Baia F, Montesissa C.This study investigated whether a single intra-articular administration (IA) of dexamethasone (DEX) in horses at therapeutic dosage could exert a systemic effect by influencing the hypothalamic-pituitary-adrenal axis activity as a consequence of (limited) absorption and systemic distribution. The results indicated that DEX was detectable in urine collected 12-48 h after IA administration and that injection was accompanied by a reduced urine excretion of cortisol, 6β-hydroxycortisol (6βOHF) and two other metabolites of cortisol lasting up to 48 h post-DEX administration. The systemic effect...
Kitaoka Y, Endo Y, Mukai K, Aida H, Hiraga A, Takemasa T, Hatta H.To evaluate the effects of a single incremental exercise test (IET) on mRNA expression and protein content of monocarboxylate transporter (MCT) 1 and MCT4 in the gluteus medius muscle of Thoroughbreds. Methods: 12 Thoroughbreds (6 males and 6 females; age, 3 to 4 years). Methods: Horses underwent an IET before and after 18 weeks of high-intensity exercise training (HIT). Horses were exercised at 90% of maximal oxygen consumption for 3 minutes during the initial 10 weeks of HIT and 110% of maximal oxygen consumption for 3 minutes during the last 8 weeks of HIT. Gluteus medius muscle biopsy spec...
Wang L, Luo DK, Pan ZY.The aim of the present study was to investigate the association between glucocorticoid receptors and steroid‑induced avascular necrosis of the femoral head (SANFH). Healthy New Zealand rabbits were randomly divided into 3 groups (n=16/group); the normal (no treatment), control (horse serum injections) and treatment (horse serum and methylprednisolone injections) groups. Methylprednisolone and horse serum injections were used to establish a SANFH model in rabbits; magnetic resonance imaging (MRI) and histopathological analysis were used to evaluate the SANFH rabbit model. Total cholesterol an...
Gauff F, Patan-Zugaj B, Licka TF.Insulin leads to overexpression of endothelin-1 (ET-1) in the endothelium of insulin-resistant rodents. If this is also the case in equine laminar tissue, this could explain the predisposition of insulin-resistant horses to laminitis. Objective: To investigate the effect of hyperinsulinaemia on metabolism and vascular resistance of the isolated equine digit in a model of extracorporeal perfusion. Methods: Randomised, controlled study with interventional group, with blinded evaluation of histology results. Methods: After exsanguination, equine digits (n = 11) and autologous blood were collected...
Ögren G, Holtenius K, Jansson A.This study examined the P balance and fecal P losses in growing Standardbred horses in training fed a forage-only diet with or without P supplementation and assessed the magnitude and proportion of the soluble, inorganic P (Pi) fraction in feces. Fourteen Standardbred horses (aged 20.0 ± 0.3 mo) adapted to ad libitum intake of grass forage containing 0.25% P were used in a crossover experiment investigating 2 dietary treatments with (high-P) and without (low-P) mineral supplementation for 6 d. Daily feed intake and refusals were weighed. Spot samples of feces were collected twice daily on d 4...
McGovern KF, Lascola KM, Smith SA, Clark-Price SC, Wilkins PA, Schaeffer DJ, Foreman JH.Hyperglycemia and endotoxemia have been associated with coagulation abnormalities in horses. Studies in humans suggest greater disturbances in coagulation with hyperglycemia and concurrent endotoxemia. Objective: To compare coagulation parameters in horses administered with lipopolysaccharide (LPS) with and without concurrent hyperglycemia. Methods: Twelve healthy adult horses. Methods: Hyperglycemia (180-240 mg/dL) was maintained for 6 hours in 6 horses (GLU-LPS) using 140 mg/kg IV bolus of dextrose followed by a 20% dextrose constant rate infusion. A similar volume of saline was administe...
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...
Maes A, Weiland L, Sandersen C, Gasthuys F, De Backer P, Croubels S.A sensitive method for the quantification of lidocaine and its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), in animal plasma using high-performance liquid chromatography combined with electrospray ionization mass spectrometry is described. The sample preparation includes a liquid-liquid extraction with methyl tert-butylmethyl ether after addition of 2M sodium hydroxide. Ethylmethylglycinexylidide (EMGX) is used as an internal standard. For chromatographic separation, an ODS Hypersil column was used. Isocratic elution was achieved with 0.01 M ammonium acetate and aceto...
Geor RJ, McCutcheon LJ.The large metabolic heat load generated as a consequence of muscular work requires activation of thermoregulatory mechanisms in order to prevent an excessive and potentially dangerous rise in body temperature during exercise. Although the horse has highly efficient heat dissipatory mechanisms, there are a number of circumstances in which the thermoregulatory system may be overwhelmed, resulting in the development of critical hyperthermia. The risk for development of life-threatening hyperthermia is greatest when (1) the horse is inadequately conditioned for the required level of physical perfo...
Freeman DE.Maintenance fluid therapy is challenging in horses that cannot drink or are denied feed and water because of concerns about gastrointestinal tract function and patency. Intravenous fluid delivery to meet water needs based on current recommendations for maintenance requirements were obtained in fed horses and therefore might not apply to horses that are not being fed. This is a critical flaw because of the interdependence between intestinal tract water and extracellular water to support digestion while preserving water balance, a concept explained by the enterosystemic cycle. Because horses dri...
Schmitz A, Demmel S, Peters LM, Leeb T, Mevissen M, Haase B.Cytochrome P450 enzymes (CYP450s) represent a superfamily of haem-thiolate proteins. CYP450s are most abundant in the liver, a major site of drug metabolism, and play key roles in the metabolism of a variety of substrates, including drugs and environmental contaminants. Interaction of two or more different drugs with the same enzyme can account for adverse effects and failure of therapy. Human CYP3A4 metabolizes about 50% of all known drugs, but little is known about the orthologous CYP450s in horses. We report here the genomic organization of the equine CYP3A gene cluster as well as a compara...
Schuback K, Essén-Gustavsson B, Persson SG.The aim was to study metabolic response and locomotion pattern in Standardbred trotters during incremental treadmill exercise performed by increasing speed by 1 m/s in 1 min steps (start 7 m/s) until the onset of fatigue. The test protocol included determination of oxygen uptake, heart rate (HR), stride length (SL) and stride frequency (SF). Venous blood samples were collected at rest, at the end of each exercise step and after 30 min of recovery. Muscle biopsies were taken at rest and post exercise and muscle temperature was measured after exercise. As horses fatigued at different speed steps...
Dickey EJ, McKenzie HC, Brown KA, de Solis CN.Continuous-rate infusions (CRI) of lidocaine are often used for prolonged duration but, to date, only limited time/concentration relationships administered as a short term (24 h) CRI have been reported. Objective: To determine the time/concentration profile of lidocaine and its active metabolites glycinexylidide (GX) and monoethylglycinexylidide (MEGX) during a 96 h lidocaine infusion. Methods: Lidocaine was administered to 8 mature healthy horses as a continuous rate infusion (0.05 mg/kg bwt/min) for 96 h. Blood concentrations of lidocaine, GX and MEGX were determined using high performance l...
Bertin FR, Pader KS, Lescun TB, Sojka-Kritchevsky JE.To evaluate the effect of ovariectomy on insulin sensitivity in horses and determine whether the effects of suppression of the hypothalamo-pituitary-adrenal axis differ before and after ovariectomy. Methods: 6 healthy mares. Methods: The horses underwent an IV glucose tolerance test (IVGTT), an insulin sensitivity test, and a dexamethasone suppression test before and 5 weeks after ovariectomy. Body weight, serum cortisol and plasma ACTH concentrations, serum insulin-to-blood glucose concentration ratios, and changes in blood glucose concentration with time after injection of glucose or insulin...
McKinney AR, Suann CJ, Stenhouse AM.A method has been developed for the detection of modafinil and its major metabolite, modafinil acid, in equine urine by solid-phase extraction and positive ion electrospray ionisation liquid chromatography/mass spectrometry. The method has been applied to the analysis of equine urine samples obtained after the oral administration of modafinil. Modafinil acid was the major component in the urine, and was detected up to 4 days post-administration. Unchanged modafinil was present at substantially lower concentrations, and was detected for only 24 hours.
Christmann U, Hancock CL, Poole CM, Emery AL, Poovey JR, Hagg C, Mattson EA, Scarborough JJ, Christopher JS, Dixon AT, Craney DJ, Wood PL.Horses with asthma or osteoarthritis frequently receive ω-3 fatty acid supplements. Docosahexaenoic (DHA; 22:6) and eicosapentaenoic (EPA; 20:5) acids are essential ω-3 fatty acid precursors of anti-inflammatory mediators and components of structural glycerophospholipids (GPL) that act as reservoirs of these fatty acids. Analysis of the incorporation of dietary DHA + EPA into GPL pools in different body compartments has not been undertaken in horses. We undertook a detailed study of dietary supplementation with DHA + EPA in horses and monitored incorporation into DHA- and EPA-contain...
Kang OD, Ryu YC, Yun YM, Kang MS.The changes in physiologic parameters by swim exercise duration were examined in five female well-trained Jeju crossbred riding horses that had riding experience of more than three years without swim training experience. The horses were performed with swim exercise for 10 min (60.0 m/min) once a day for 14 days. Physiologic characteristics and haematic parameters were measured before swimming, immediately after swimming, and after a 10 min rest at first day (D0), 7 days (D7), and 14 days (D14) of training. After 14 days of swim training, heart rate (p<0.05), blood glucose (p<0.05), lacta...
McAnulty JF, Stone WC, Darien BJ.The purpose of this study was to examine the effects of ischemia and reperfusion on the biochemical integrity of equine colonic mucosa to assess the relative roles of ischemic- and reperfusion-induced damage. Methods: Two hours of no-flow ischemia experimentally induced by 720 degrees counterclockwise ascending colon volvulus followed by 2 hours reperfusion after derotation. Methods: Ten ponies. Methods: Ascending colon biopsies were obtained every hour for measurement of mucosal adenosine triphosphate (ATP), water, sodium, and potassium content. Additional samples were homogenized for assay o...
Morris EA, Treadwell BV.The effect of interleukin 1 (IL-1) on equine articular cartilage was investigated, using a cartilage explant culture system. Measurement of [35S]O4 incorporation revealed synthesis of matrix proteoglycan by cartilage to be decreased 45, 59.7, and 37.5% after 1, 3, and 5 days, respectively, in culture in the presence of 5 U of IL-1/ml. There was no change in proteoglycan degradation as determined by measurement of [35S]O4 release into the culture medium. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cartilage-conditioned medium indicated that exposure of cartilage to IL-1 caused ...
Olsman AF, Huurdeman CM, Jansen WL, Haaksma J, Sloet van Oldruitenborgh-Oosterbaan MM, Beynen AC.In a cross-over study with six mature horses, the effect of iso-energetic replacement of dietary glucose by beet pulp on macronutrient digestibility, nitrogen metabolism and mineral absorption was studied. The test ration contained 25% beet pulp in the total dietary dry matter. Beet pulp feeding significantly lowered crude fat and non-structural carbohydrate digestibility, but had no significant effect on digestibility of other macronutrients, faecal and urinary nitrogen excretion and the faecal to urinary nitrogen excretion quotient. However, on the beet pulp diet, plasma ammonia and creatini...
Silver M.Placental progestagen production and metabolism during pregnancy, the changes which precede parturition and the extent of fetal involvement in the latter processes are compared in the sheep and the horse. Neither species requires the presence of a corpus luteum for maintenance of the latter part of pregnancy, but the mechanisms involved in placental progesterone/progestagen production are very different in the two species. In sheep the primary product is progesterone (P4), levels of which are high in the maternal but not the fetal circulations. By contrast, in the mare P4 is not detectable in ...
Schipke J, Mayhew TM, Mühlfeld C.Body mass (BM) of terrestrial mammalian species ranges from a few grams in the case of the Etruscan shrew to a few tonnes for an elephant. The mass-specific metabolic rate, as well as heart rate, decrease with increasing BM, whereas heart mass is proportional to BM. In the present study, we investigated the scaling behaviour of several compartments of the left ventricular myocardium, notably its innervation, capillaries and cardiomyocytes. Myocardial samples were taken from 10 mammalian species with BM between approximately 2 g and 900 kg. Samples were analysed by design-based stereology and e...
Wootton JF, Argenzio RA.The distribution of nitrogen in ligated segments of the stomach and intestine of two groups of ponies has been examined at sacrifice 2, 4, 8, and 12 h following the final 12-h scheduled feeding of diets designed to provide either 1) ample protein, or 2) limited protein plus supplemental urea as the major nitrogen source. Concentrations and total quantities of total N, NH3, urea plus NH3, and alpha-amino N were determined, and protein N was calculated by difference. Liquid marker (PEG) distribution rate constants and N concentrations were used to calculate rates of entry and exit by digesta flo...
French KR, Pollitt CC.Acute laminitis is characterised by hoof lamellar dermal-epidermal separation at the basement membrane (BM) zone. Hoof lamellar explants cultured in vitro can also be made to separate at the basement membrane zone and investigating how this occurs may give insight into the poorly understood pathophysiology of laminitis. Objective: To investigate why glucose deprivation and metalloproteinase (MMP) activation in cultured lamellar explants leads to dermo-epidermal separation. Methods: Explants, cultured without glucose or with the MMP activator p-amino-phenol-mercuric acetate (APMA), were subject...
Frank N, Sojka JE, Latour MA.To measure and compare the concentration and composition of very low-density lipoprotein (VLDL) in plasma and selected lipids in serum of horses fed mixed grass hay ad libitum or denied feed for 36 hours. Methods: 4 healthy adult mares. Methods: Mares were either fed mixed grass hay ad libitum or denied feed for 36 hours beginning at 8:00 AM. Blood samples were collected every 2 hours during the study period and analyzed for nonesterified fatty acid (NEFA), triglyceride (TG), VLDL, and glucose concentrations and composition of VLDL. Results: Withholding feed significantly increased mean serum ...
Clarke LL, Argenzio RA, Roberts MC.The effect of meal size and frequency on plasma volume, plasma aldosterone concentration and urinary Na and K clearances was determined in ponies. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen, ie, 12 equal portions fed at 2-hour intervals, or as single large feedings, ie, half the ration fed every 12 hours at 0800 and 2000 hours. Only the effect of the single morning feeding was studied, using the latter regimen. Serial measurements of plasma volume were made by use of an indicator-dilution technique and indocyanine green (0.15 mg/kg of body...
Tesena P, Kingkaw A, Vongsangnak W, Pitikarn S, Phaonakrop N, Roytrakul S, Kovitvadhi A.Equine melanocytic neoplasm (EMN) is a cutaneous neoplasm and is mostly observed in aged grey horses. This preliminary study aimed to identify potential proteins to differentiate normal, mild and severe EMN from serum proteomic profiling. Serum samples were collected from 25 grey horses assigned to three groups: normal (free of EMN; = 10), mild ( = 6) and severe EMN ( = 9). To explore the differences in proteins between groups, proteomic profiling and analysis were employed. Accordingly, 8241 annotated proteins out of 8725 total proteins were compared between normal and EMN groups and inspect...
González O, González E, Sánchez C, Pinto J, González I, Enríquez O, Martínez R, Filgueira G, White A.The effects of exercise stress on erythrocyte beta-adrenergic receptor characteristics and plasma concentrations of adrenaline, noradrenaline and thyroid hormones were studied in Thoroughbred racehorses during rest and after exercise. Five minutes after a maximal speed race of 1200 +/- 200 m (mean +/- s.d.), both plasma adrenaline and noradrenaline concentrations increased with respect to basal values (from 2.48 +/- 0.15 to 3.83 +/- 0.27 and from 2.13 +/- 0.11 to 3.53 +/- 0.27 nmol/l respectively). The increment of adrenaline was greater in high performance (HP) as compared to low performance ...
Weber JM, Parkhouse WS, Dobson GP, Harman JC, Snow DH, Hochachka PW.Plasma lactate turnover rate of Thoroughbred racehorses was measured by bolus injection of [U-14C]lactate at rest and two levels of submaximal treadmill exercise (3-4 m/s trot, 6% incline, and 6.5 m/s horizontal canter). Our goals were 1) to determine the relative effects of changes in cardiac output and in plasma lactate concentration on turnover rate [using cardiac output data from Weber et al. (28)] and 2) to assess the importance of lactate as a metabolic fuel in a trained animal athlete. Lactate turnover rates were 9.3 mumol.min-1.kg-1 (rest), 75.9 mumol.min-1.kg-1 at the beginning of the...
Yamano S, Eto D, Hiraga A, Miyata H.To consider the optimal training programme for Thoroughbred horses, we examined the recruitment pattern of muscle fibres including hybrid muscle fibres in well-trained Thoroughbred horses. The horses performed exercise at three different intensities and durations; i.e., 100% VO2max for 4 min, 80% and 60% VO2max for 8 min on a treadmill with 10% incline. Muscle samples were obtained from the middle gluteal muscle before, during (4 min at 80% and 60% VO2max), and after exercise. Four muscle fibre types (types I, IIA, IIA/IIX, and IIX) were immunohistochemically identified, and optical density of...
Assenza A, Marafioti S, Congiu F, Giannetto C, Fazio F, Bruschetta D, Piccione G.The effect of two jumping competitions, performed in two consecutive weekends, on serum creatine phosphokinase (CPK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), urea, creatinine (CREA) concentrations were evaluated in 12 healthy jumper horses. Methods: Blood sampling was performed before the 1(st) day of competition (T0), at the end of each show (J1, J2), on the day after the competition (T1); the same sampling plan was followed during the second weekend (J3, J4 and T2). Results: One-way repeated measures analysis of variance showed an increase in CPK at J1 and J2 respe...
Gokbulut C, Akar F, McKellar QA.Fenbendazole (FBZ), oxfendazole (fenbendazole sulphoxide, FBZSO), and albendazole (ABZ) were administered orally to donkeys at 10mg/kg bodyweight. Blood and faecal samples were collected from 1 to 120 h post-treatment. The plasma and faecal samples were analysed by high performance liquid chromatography (HPLC). The parent molecule and its sulphoxide and sulphone (FBZSO(2)) metabolites did not reach detectable concentrations in any plasma samples following FBZ administration. ABZ was also not detected in any plasma samples, but its sulphoxide and sulphone metabolites were detected, demonstratin...
Mazan MR, Deveney EF, DeWitt S, Bedenice D, Hoffman A.This study was conducted to determine whether horses with naturally occurring, severe chronic recurrent airway obstruction (RAO) 1). have a greater resting energy expenditure (REE) than control horses, 2). suffer body mass depletion, and 3). have significantly decreased REE after bronchodilation and, therefore, also 4). whether increased work of breathing contributes to the cachexia seen in some horses with RAO. Six RAO horses and six control horses underwent indirect calorimetric measures of REE and pulmonary function testing using the esophageal balloon-pneumotachograph method before and aft...
Pollitt CC, Davies CT.The effect of alimentary carbohydrate overload on hoof temperature was investigated to determine the state of the sublamellar vasculature preceding the onset of equine laminitis. Hoof, core and ambient temperatures and heart rate were logged continuously in 21 mature Standardbred horses kept in an environmental chamber set at 10 degrees C. Recording hoof temperature was a successful, noninvasive, method to measure indirectly, shifts in digital blood flow against a background of cold induced, physiological, vasoconstriction. High hoof temperatures were assumed to indicate digital vasodilation a...
Weinert-Nelson JR, Biddle AS, Sampath H, Williams CA.Integrating warm-season grasses into cool-season equine grazing systems can increase pasture availability during summer months. The objective of this study was to evaluate effects of this management strategy on the fecal microbiome and relationships between fecal microbiota, forage nutrients, and metabolic responses of grazing horses. Fecal samples were collected from 8 mares after grazing cool-season pasture in spring, warm-season pasture in summer, and cool-season pasture in fall as well as after adaptation to standardized hay diets prior to spring grazing and at the end of the grazing seaso...
Myer YP, Kumar S.The ascorbate reduction of horse heart ferricytochrome c in 0.05 M phosphate + 0.25 M sodium sulfate, at pH 7.3, as a function of temperature, 12-36 degrees C, and at alkaline pH 8.4 using stopped flow technique has been examined. The data have been analyzed in terms of a two-step mechanism, binding followed by reduction (Myer, Y.P., Thallam, K.K., and Pande, A. (1980) J. Biol. Chem. 255, 9666-9673). At neutral pH and up to about 26 degrees C, the first order reduction constant is independent of temperature, i.e. with zero or near-zero activation energy. At higher temperatures, it becomes temp...
