Insulin is a hormone produced by the pancreas that plays a pivotal role in regulating glucose metabolism in horses. It facilitates the uptake of glucose by cells, thus maintaining blood sugar levels within a normal range. Insulin's function is integral to energy balance and metabolic processes in equines. Disruptions in insulin regulation can lead to metabolic disorders such as Equine Metabolic Syndrome (EMS), characterized by insulin resistance and associated with obesity and laminitis. This page aggregates peer-reviewed research studies and scholarly articles that explore the physiological role, regulatory mechanisms, and clinical implications of insulin in equine health and disease management.
Toribio RE, Kohn CW, Rourke KM, Levine AL, Rosol TJ.To determine effects of experimentally induced hypercalcemia on serum concentrations and urinary excretion of electrolytes, especially ionized magnesium (iMg), in healthy horses. Methods: 21 clinically normal mares. Methods: Horses were assigned to 5 experimental protocols (1, hypercalcemia induced with calcium gluconate; 2, hypercalcemia induced with calcium chloride; 3, infusion with dextrose solution; 4, infusion with sodium gluconate; and 5, infusion with saline [0.9% NaCl] solution). Hypercalcemia was induced for 2 hours. Dextrose, sodium gluconate, and saline solution were infused for 2 ...
Geor RJ, Larsen L, Waterfall HL, Stewart-Hunt L, McCutcheon LJ.No studies in horses have examined the effect of route of carbohydrate (glucose) administration on the rate of muscle glycogen storage following glycogen-depleting exercise. Objective: Glucose delivery from the gastrointestinal tract limits the rate of muscle glycogen storage following glycogen-depleting exercise. Methods: In a crossover design, 7 fit horses completed treadmill exercise (EX) on 3 occasions to deplete muscle glycogen by approximately 50%. After EX horses received: 1) i.v. glucose infusion (IV; 0.5 g/kg bwt/h for 6 h), 2) oral glucose boluses (OR; 1 g/kg bwt at 0, 2 and 4 h post...
Gordon ME, McKeever KH, Bokman S, Betros CL, Manso-Filho H, Liburt N, Streltsova J.Horses in training tend to become inappetant; however, the mechanism responsible for this training-induced inappetance is not known. Objective: Training and/or ulcers alter the feed intake (FI) and hormonal and/or biochemical (active ghrelin, leptin, glucose, insulin and cortisol) responses to acute high intensity exercise. Methods: Eight Standardbred mares underwent 3 interval exercise tests (IET) and 3 parallel control tests (CON) before (IET1) and after 8 weeks of training (IET2) and after treatment for gastric ulcers (IET3). Plasma samples were taken before (0 min), during (last 10 sec of ...
Treiber KH, Hess TM, Kronfeld DS, Boston RC, Geor RJ, Friere M, Silva AM, Harris PA.Glucose regulation is critical for health and exercise performance. Objective: To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. Methods: This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n = 6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIG...
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...
Zeyner A, Hoffmeister C, Einspanier A, Gottschalk J, Lengwenat O, Illies M.Quarter Horses are particularly susceptible to polysaccharide storage myopathy (PSSM). Nutritional therapy and possibly prophylaxis includes fat-supplemented diets whilst starch supply should be kept to a minimum. Objective: To investigate the glycaemic and insulinaemic response of clinically normal Quarter Horses to concentrates high in fat and low in starch. Methods: Twelve Quarter Horses were studied. The precondition for inclusion in the study population was that the horses had not shown clinical signs of myopathy. The Quarter Horses were fed according to a 4 x 4 Latin square design haylag...
Lindberg JE, Essén-Gustavsson B, Dahlborn K, Gottlieb-Vedi M, Jansson A.High starch intakes increase the risk for metabolic disorders and therefore alternative feedstuffs are of interest. High-fat oat varieties have a lower starch and higher energy content than regular oats and may therefore be useful in this context. Objective: Feeding high fat oats causes no adverse effects on the response to exercise and that the total amount of oats offered could be reduced compared to feeding with regular oats. Methods: Twelve Standardbred trotters were fed regular oats (diet C), high-fat oats (F), and a mixture (50:50) of C and F (M), together with haylage (30:70), in a Lati...
Stewart-Hunt L, Geor RJ, McCutcheon LJ.Increased insulin sensitivity occurs after a period of exercise training, but the mechanisms underlying this training-associated increase in insulin action have not been investigated. Objective: To examine the effects of short-term endurance training (7 consecutive days) and a subsequent period of inactivity (5 days) on whole body insulin sensitivity and GLUT-4 protein and the activities of glycogen synthase (GS) and hexokinase (HK) in skeletal muscle. It was hypothesised that training would increase insulin sensitivity in association with increased GLUT-4 protein and activities of GS and HK, ...
Pratt SE, Geor RJ, McCutcheon LJ.There is evidence that adaptation to diets rich in nonstructural carbohydrates (NSC) contributes to the development of insulin resistance in horses. To date, however, no study in horses has examined the effects of physical conditioning on diet-associated alterations in insulin sensitivity and glucose tolerance. Objective: To examine the effects of adaptation to concentrate feeds rich in NSC or fat on insulin sensitivity and glucose tolerance in horses, both in the sedentary state and after a subsequent period of physical conditioning. Methods: Fourteen mature Standardbred horses underwent both...
de Graaf-Roelfsema E, van Ginneken ME, van Breda E, Wijnberg ID, Keizer HA, van der Kolk JH.To study the possible long-term effect of improved glucose tolerance in horses after long-term training, as the impact of exercise training on glucose metabolism is still unclear in the equine species. It is not known whether there is a direct long-term effect of training or if the measurable effect on glucose metabolism is the residual effect of the last exercise session. Objective: To determine the chronic effect on glucose metabolism and peripheral insulin sensitivity of long-term training in horses by use of the euglycaemic hyperinsulinaemic clamp technique. Methods: Eleven Standardbred ho...
McCutcheon LJ, Geor RJ, Pratt SE, Martineau E, Ho K.Exercise is an important stimulus for the regulation of numerous metabolic functions in muscle, but there has been little investigation of the mechanism of exercise-enhanced glucose utilisation. Objective: To examine the effects of exercise on the signalling components Akt and glycogen synthase kinase-3 (GSK3) involved in insulin regulation of glycogen synthase (GS) activity. It was hypothesised that hyperinsulinaemia and prior exercise would alter the extent of Akt phosphorylation and GSK3beta deactivation and increase insulin stimulation of GS activity in skeletal muscle. Methods: Eight Stan...
Vick MM, Adams AA, Murphy BA, Sessions DR, Horohov DW, Cook RF, Shelton BJ, Fitzgerald BP.Recent studies associate obesity and insulin resistance in horses with development of abnormal reproductive function and debilitating laminitis. The factors contributing to insulin resistance in obese horses are unknown. However, human studies provide evidence that elevated inflammatory cytokines such as tumor necrosis factor alpha (TNFalpha), IL1, and IL6 play direct roles in development of obesity-associated insulin resistance. Thus, inflammation may be a key link between obesity and insulin resistance in horses. The aim of the current investigation was to examine possible relationships betw...
Eades SC, Stokes AM, Johnson PJ, LeBlanc CJ, Ganjam VK, Buff PR, Moore RM.To quantify changes in endothelium-derived factors and relate those changes to various aspects of digital hemodynamics during the prodromal stages of carbohydrate overload (CHO)-induced laminitis in horses. Methods: 20 adult horses without abnormalities of the digit. Methods: Digital and jugular venous blood samples were collected at 1-hour intervals (for assessment of endothelin-1 [ET-1] immunoreactivity and measurement of glucose, insulin, and nitric oxide [NO] concentrations) or 4-hour intervals (CBC and platelet-neutrophil aggregate assessment) for 8 hours or 16 hours after induction of CH...
Noble GK, Houghton E, Roberts CJ, Faustino-Kemp J, de Kock SS, Swanepoel BC, Sillence MN.Insulin-like growth factor-1 could be a useful marker in the horse for diagnostic, selection, or forensic purposes, provided its physiological regulation is well understood. The objective of this study was to investigate factors, such as acute exercise, fitness training, time of day, sex, and age, that may influence serum IGF-1 in normal, healthy horses. Throughout a 9-wk training program, 6 geldings maintained a mean (+/- SEM) IGF-1 concentration of 302 +/- 29 ng/mL. Moderate or high intensity exercise had no effect on IGF-1 concentrations, when pre- and postexercise values were compared. Ove...
Manso Filho HC, McKeever KH, Gordon ME, Costa HE, Watford M.One of the hallmarks of insulin resistance is a reduction in glucose transporter-4 (Glut-4) expression in adipose tissue but not in skeletal muscle. However, while Glut-4 has been demonstrated in skeletal and cardiac muscles in horses it has not been demonstrated in adipose tissue. The initial objectives of the present study were: (1) to test the hypothesis that Glut-4 expression would vary between selected key skeletal muscles; (2) to test the hypothesis that it would also vary between representative adipose tissue depots, and (3) to see whether expression would be greater in adipose tissue c...
Hodavance MS, Ralston SL, Pelczer I.Metabonomic analysis is a powerful tool for identifying and characterizing metabolic disorders, for example type 2 diabetes and the metabolic syndrome. Nuclear magnetic resonance (NMR) spectroscopy is an essential tool for such analysis, with special benefits. The review assesses the current status and potential of NMR-based metabonomics of type 2 diabetes. The horse is proposed as a possible model for studying this condition and disease. Some examples are shown of horse blood analyses by NMR.
Buff PR, Spader BR, Morrison CD, Keisler DH.Leptin, a protein hormone secreted by adipocytes, plays an important role in energy homeostasis and regulation of body composition. We previously observed that acute feed restriction resulted in a rapid decline in concentrations of leptin in obese pony mares. This acute response prompted us to characterize the temporal changes in concentrations of leptin, GH, and insulin in obese pony mares during the transition between fed and feed-restricted conditions. Nine obese pony mares of mixed breed, previously maintained on fescue pasture, were randomly allotted to 2 groups. Treatments consisted of a...
Wilson AD, Badnell-Waters AJ, Bice R, Kelland A, Harris PA, Nicol CJ.High carbohydrate diets can affect the health and behaviour of foals, but the mechanisms are not always fully understood. The objective of this study was to compare the effects of feeding a starch and sugar (SS), or a fat (oil) and fibre (FF) rich diet to two groups of eight foals. Diets were fed from 4 to 42 weeks of age, alongside ad libitum forage. Faecal pH levels did not differ significantly between groups and endoscopic examination showed that the gastric mucosa was healthy in both groups at 25 and 42 weeks of age. At 40 weeks of age, SS foals had significantly higher total blood glucose...
Vick MM, Sessions DR, Murphy BA, Kennedy EL, Reedy SE, Fitzgerald BP.In mares, obesity is associated with continuous reproductive activity during the non-breeding season. To investigate the effect of obesity and associated alterations in metabolic parameters on the oestrous cycle, two related studies were conducted. In Experiment 1, obese (body condition score > 7) mares were fed ad libitum or were moderately feed restricted during the late summer and autumn months. Feed restriction did not alter the proportion of mares entering seasonal anoestrus. However, obese mares exhibited a significantly longer duration of the oestrous cycle, significant increases in ...
Porter RM, Akers RM, Howard RD, Forsten-Williams K.Interleukin-1 (IL-1) and insulin-like growth factor-I (IGF-I), which have opposing effects on matrix metabolism within articular cartilage, are thought to play prominent roles in the pathogenesis of osteoarthritis. To better understand the link between these anabolic (IGF-I) and catabolic (IL-1) stimuli, we examined exogenous IL-1 regulation of the IGF-I signaling system of articular chondrocytes (ACs). Equine ACs from non-arthritic stifle joints were expanded in monolayer culture, encapsulated for 10 days in alginate beads, and stimulated as high-density monolayers with recombinant equine IL-...
Gordon ME, McKeever KH.This study tested the hypothesis that grain and intravenous dextrose challenges would alter plasma concentrations of active ghrelin, adiponectin, leptin, glucose, insulin, and cortisol in Standardbred mares. To deliver 0.5 g of glucose (dextrose solution for the intravenous test)/kg of BW, mares received intravenous dextrose (50% solution) or oral grain administration in 2 trials. In response to the oral grain challenge, plasma glucose and insulin concentrations increased (P < 0.001) by 56 and 802%, respectively. Plasma ghrelin concentration initially decreased (P < 0.001) by 40%, then s...
The Journal of nutritionJune 15, 2006
Volume 136, Issue 7 Suppl 2090S-2093S doi: 10.1093/jn/136.7.2090S
Kronfeld DS, Treiber KH, Hess TM, Splan RK, Byrd BM, Staniar WB, White NW.Treatment of clinical laminitis usually fails to prevent some degree of persistent disability; thus, intervention should aim at avoiding risk factors and preventing the disease. Efficiency of intervention would be improved by identifying predisposed horses and ponies. A herd of 160 healthy ponies included 54 previously laminitic (PL) and 106 never laminitic (NL). Pedigree analysis was consistent with dominant inheritance partially suppressed in males. Blood analysis revealed higher plasma concentrations of insulin and triglycerides but not cortisol, glucose, or free fatty acids in the PL group...
The Journal of nutritionJune 15, 2006
Volume 136, Issue 7 Suppl 2094S-2098S doi: 10.1093/jn/136.7.2094S
Treiber KH, Kronfeld DS, Geor RJ.Insulin is a major regulatory hormone in glucose and fat metabolism, vascular function, inflammation, tissue remodeling, and the somatotropic axis of growth. Insulin resistance alters insulin signaling by decreasing insulin action in certain resistant pathways while increasing insulin signaling in other unaffected pathways via compensatory hyperinsulinemia. In humans, altered insulin signaling is implicated in reduced glucose availability to insulin-sensitive cells, vasoconstriction and endothelial damage, and inflammatory response. Although no direct evidence exists for insulin's role in thes...
The Journal of nutritionJune 15, 2006
Volume 136, Issue 7 Suppl 2114S-2121S doi: 10.1093/jn/136.7.2114S
Harris P, Bailey SR, Elliott J, Longland A.Laminitis occurs throughout the world in horses and ponies and has major welfare implications. It is obviously important to be able to recognize and treat the condition in its early stages so that pain and suffering are kept to a minimum. However, ideally it would be preferred to be able to recommend certain interventions/countermeasures that avoid or prevent the condition from occurring in the first place. Because pasture-associated laminitis occurs with grass consumption, one obvious way to avoid the condition is to prevent access to pasture and to feed forage alternatives that are known to ...
Goodrich LR, Brower-Toland BD, Warnick L, Robbins PD, Evans CH, Nixon AJ.Insulin-like growth factor-I (IGF-I) is one of the most influential growth factors in cartilage repair. Maintenance of adequate IGF-I levels after articular repair procedures is complicated by the short biological half-life of IGF-I in vivo. This study investigated the potential for more prolonged IGF-I delivery through direct adenoviral mediated transduction of synovial tissues in the metacarpophalangeal (MCP) joints of horses. The use of a large animal model provided a structurally similar and metabolically relevant corollary to the human knee. The complete IGF-I coding sequence was packaged...
Oikawa S, McGuirk S, Nishibe K, Higuchi T, Kurosawa T, Watanuki M, Satoh H.Hyperlipemia in horses is a disorder of lipid metabolism peculiar to ponies. This study reports changes of blood biochemical values from the acute to the postconvalescent phases in 3 Shetland ponies with hyperlipemia in Japan. Diseased ponies (all 7 to 9 years old, in late pregnancy, and obese) were fed in the same farm. The periods of their hospitalizations ranged from 30 to 45 days. Twelve well-conditioned ponies (3 to 13 years old) around parturition were used to establish baseline values for blood test results. Main clinical findings in the affected ponies were depression, dysphagia, anore...
Treiber KH, Kronfeld DS, Hess TM, Byrd BM, Splan RK, Staniar WB.To evaluate genetic and metabolic predispositions and nutritional risk factors for development of pasture-associated laminitis in ponies. Methods: Observational cohort study. Methods: 160 ponies. Methods: A previous diagnosis of laminitis was used to differentiate 54 ponies (PL group) from 106 nonlaminitic ponies (NL group). Pedigree analysis was used to determine a mode of inheritance for ponies with a previous diagnosis of laminitis. In early March, ponies were weighed and scored for body condition and basal venous blood samples were obtained. Plasma was analyzed for glucose, insulin, trigly...
Frank N, Elliott SB, Brandt LE, Keisler DH.To compare obese horses with insulin resistance (IR) with nonobese horses and determine whether blood resting glucose, insulin, leptin, and lipid concentrations differed between groups and were correlated with combined glucose-insulin test (CGIT) results. Methods: 7 obese adult horses with IR (OB-IR group) and 5 nonobese mares. Methods: Physical measurements were taken, and blood samples were collected after horses had acclimated to the hospital for 3 days. Response to insulin was assessed by use of the CGIT, and maintenance of plasma glucose concentrations greater than the preinjection value ...
Jose-Cunilleras E, Hinchcliff KW, Lacombe VA, Sams RA, Kohn CW, Taylor LE, Devor ST.Fatiguing exercise substantially decreases muscle glycogen concentration in horses, impairing athletic performance in subsequent exercise bouts. Our objective was to determine the effect of ingestion of starch-rich meals after exercise on whole body glucose kinetics and muscle glycogen replenishment. In a randomized, cross-over study seven horses with exercise-induced muscle glycogen depletion were either not fed for 8 h, fed half of the daily energy requirements ( approximately 15 Mcal DE) as hay, or fed an isocaloric amount of corn 15 min and 4 h after exercise. Starch-rich meals fed after e...
Buff PR, Johnson PJ, Wiedmeyer CE, Ganjam VK, Messer Iv NT, Keisler DH.Horses fed beyond their nutritional requirement and that are physically inactive will develop obesity, which is often accompanied by insulin resistance and heightened risk of laminitis. The use of pharmacologic agents in combination with nutritional restriction may promote weight loss in obese horses unable to exercise because of laminitic pain. This study shows that reducing feed intake of brome grass hay to 75% of ad libitum intake in obese pony mares reduces body weight without induced exercise. Additional supplementation of ractopamine hydrochloride for 6 weeks resulted in a tendency for i...
Ericsson AC, Johnson PJ, Gieche LM, Zobrist C, Bucy K, Townsend KS, Martin LM, LaCarrubba AM.Common treatments for Equine Metabolic Syndrome (EMS) and associated conditions include removal from pasture and adoption of an all-hay diet. Pharmacological treatments for EMS include metformin, a biguanide antihyperglycemic agent also administered to people to help improve glucose tolerance and insulin sensitivity. Both treatments may work, at least partially, through the gut microbiota, yet little is known regarding these effects in the equine host. To determine the influence on the fecal microbiota of this diet change and administration of metformin, six healthy horses were removed from pa...
Greene HM, Cogger EA, Miltenberger TL, Koch AK, Bray RE, Wickler SJ.Altitude evokes physiological adjustments that include not only respiratory and cardiovascular properties, but also metabolic function, renal and endocrine responses. The purpose of the present study was designed to expand our understanding of the physiological process involved with acclimatisation to high altitude in equids. The study examined temporal effects on metabolic and osmoregulatory function in horses (n = 6) at rest and postexercise at 3800 m. Animals were studied at 225 m (Pb = 743 mmHg) and during a 10 day stay at altitude (Pb = 487 mmHg). Rest samples were taken 90 min postprandi...
Jacquay ET, Harris PA, Adams AA.Transportation of horses on short journeys can lead to an increase in stress. There are known age-associated changes in immune and metabolic responses in horses; however, no research exists evaluating how age may influence these responses to transportation stress. Eleven mares within two age groups, aged (n = 5, 22 ± 1 year) or young (n = 6, 2 ± 1 year), were transported 1 hour and 20 minutes. Peripheral blood and saliva were collected before and after transportation at baseline (2 to 3 weeks prior to transportation), 24 hours pre-transport, 1 hour before loading, 15 minutes, 30 minutes,...
Field JR, Jeffcott LB.Laminitis is an important condition in horses and ponies, not just because of the seriousness of the clinical signs and systemic changes involved, but because of the potentially poor prognosis and likelihood of recurrence. Laminitis is particularly prevalent in ponies and involves a multiplicity of aetiological factors. Fat ponies and those having previously suffered laminitis were found to be far more intolerant to oral glucose loading (1 g/kg bwt) than normal ponies or Standardbred horses. These ponies also exhibited a far greater response in plasma insulin levels after glucose loading. Insu...
Slebodziński AB, Brzezińska-Slebodzińska E, Nowak J, Kowalska K.It is generally accepted that hormones and tissue growth factors are supplied from mother to neonate via mammary secretion. Among the protein hormones, insulin and prolactin are considered as the most important milk components for neonates. The significance of the thyroid hormones, namely triiodothyronine (T3) generated locally by 5'-monodeiodinase (5'-MD) in the mammary tissues, for the mammary gland itself and for suckling neonates is still under consideration. In the present study the activity of the 5'-MD and the concentrations of T3 and insulin in mare's colostrum and milk during the firs...
Rambags BP, van Rossem AW, Blok EE, de Graaf-Roelfsema E, Kindahl H, van der Kolk JH, Stout TA.Insulin is a pancreatic hormone that classically regulates carbohydrate and fat metabolism, but also appears to play a role in various reproductive processes. A preliminary study suggested insulin production by day 10 to 18 equine conceptuses. The aim of the present study was to examine the hypothesis that insulin is the conceptus signal responsible for maternal recognition of pregnancy (MRP) in the mare, or otherwise influences reproductive cyclicity during the MRP period. Six Warmblood mares were treated daily during days 7 to 17 after ovulation of two successive oestrous cycles with either ...
Nostell KE, Lindåse SS, Bröjer JT.Insulin resistance (IR) in humans is related to hypertension and impaired vasodilation. Insulin administration has been shown to lower blood pressure both in insulin resistant as well as in insulin sensitive individuals. The aim of the study was to investigate the association between insulin sensitivity and alterations in blood pressure in healthy horses before and after a euglycemic-hyperinsulinemic clamp (EHC). A 3-h EHC was performed in 13 healthy horses (11 mares, 2 geldings). Blood samples for measurement of plasma glucose and insulin were collected before the start of the EHC, every 10 ...
Taylor PM.Some metabolic and endocrine effects of hypercapnia were studied in six ponies during halothane anaesthesia with neuromuscular blockade and controlled ventilation. Each was anaesthetised twice, once with a 40-minute-period of hypercapnia (10 kPa) and once when normocapnia (5.3 kPa) was maintained throughout two hour's anaesthesia. Routine cardiovascular monitoring was performed and blood samples were taken for assay of cortisol, insulin, glucose, lactate, muscle and liver enzymes and total protein. Anaesthesia induced hypotension and lacticacidaemia which were slightly ameliorated during hyper...
Watson ED, Bae SE, Thomassen R, Thomson SR, Woad K, Armstrong DG.The period between seasonal anoestrus and cyclicity is characterized in many mares by cyclical growth and regression of large dominant follicles. The insulin-like growth factor (IGF) system plays a key role in follicular growth and regression; therefore, we hypothesized that changes in the IGF system and its binding proteins would modulate onset of cyclicity in mares. Ovaries were obtained from pony mares on the day after detection of an actively growing 30 mm transitional anovulatory follicle, and also at the second or third oestrus of the breeding season on the day after the preovulatory fol...
Jansson A, Harris P, Davey SL, Luthersson N, Ragnarsson S, Ringmark S.Straw's low energy content means it is a roughage option for horses with low energy requirements. Previously, in a field study, straw was associated with an increased risk for gastric ulcers. This study evaluated the effect on gastric ulcers, metabolic profile and behaviour of replacing, in a forage-only ration, 50% of the daily allowance with wheat straw. Six equines were studied in a 2 × 21-day cross-over design. The control diet (CON: 100% grass forage) and the straw diet (S: 50% grass forage and 50% straw [DM basis]) were iso-energetic. Gastroscopy was performed prior to the study and on ...
Hansen TL, Rankins EM, Bobel JM, McKinney M, Hackmann TJ, Warren LK.In humans, the consumption of soluble fibers reduces glycemic response after a meal. We hypothesized high soluble fiber diets would reduce and delay postprandial glucose and insulin responses in horses. In a 4 × 4 Latin square design experiment, four Quarter Horse geldings were adapted to diets containing orchardgrass hay (ORCH) or ORCH with 1 of 3 treatment ingredients: molassed sugar beet pulp (BEET), almond hulls (HULL), or steam-crimped oats (OATS). Blood was serially sampled for 6 hours after feeding 0.15% body weight (BW) of the treatment ingredient (meal test) or 1.1 g starch/kg BW ...
Delarocque J, Frers F, Huber K, Feige K, Warnken T.Insulin dysregulation (ID) goes along with lasting or transient hyperinsulinemia able to trigger equine laminitis, a painful and crippling foot condition. Promoting weight loss through dietary changes and physical activity is currently the main option to prevent this disease. This study aimed at describing the relationship between weight variations and the level of ID as determined by oral glucose tests (OGT). Therefore, the insulin response of 19 Icelandic horses to repeated OGTs was retrospectively analysed considering the variations in their body weight. Results: There was a strong linear r...
McCutcheon LJ, Geor RJ, Pratt SE, Martineau E, Ho K.Exercise is an important stimulus for the regulation of numerous metabolic functions in muscle, but there has been little investigation of the mechanism of exercise-enhanced glucose utilisation. Objective: To examine the effects of exercise on the signalling components Akt and glycogen synthase kinase-3 (GSK3) involved in insulin regulation of glycogen synthase (GS) activity. It was hypothesised that hyperinsulinaemia and prior exercise would alter the extent of Akt phosphorylation and GSK3beta deactivation and increase insulin stimulation of GS activity in skeletal muscle. Methods: Eight Stan...
Vervuert I, Bothe C, Coenen M.This study was conducted to evaluate the effects of different barley processing techniques on the glycaemic and insulinaemic responses in horses. It was hypothesized that the changes in pre-caecal starch digestibility caused by barley processing would affect metabolic responses. Six horses were fed in random order: whole (WB), finely ground (FGB), steamed (SB), steam-flaked (SFB) and popped barley (PB). The total barley intake was adjusted to 630 g starch/horse/day (1.2-1.5 g starch/kg BW/day). During a 10-day stabilization period, the horses also received 6 kg grass hay/horse/day. On the bloo...
Valenzuela OA, Jellyman JK, Allen VL, Holdstock NB, Forhead AJ, Fowden AL.In several species, adult metabolic phenotype is influenced by the intrauterine environment, often in a sex-linked manner. In horses, there is also a window of susceptibility to programming immediately after birth but whether adult glucose-insulin dynamics are altered by neonatal conditions remains unknown. Thus, this study investigated the effects of birth weight, sex and neonatal glucocorticoid overexposure on glucose-insulin dynamics of young adult horses. For the first 5 days after birth, term foals were treated with saline as a control or ACTH to raise cortisol levels to those of stressed...
de Laat MA, Sillence MN.Blood glucose concentration is often measured during an oral glucose test (OGT), but is not thought to aid in diagnosing insulin dysregulation (ID) or pituitary pars intermedia dysfunction (PPID). The aim of this retrospective study was to investigate whether the change in blood glucose concentration during an OGT aligned with indicators of equine metabolic syndrome or PPID, including serum insulin and plasma ACTH concentrations, clinical observations, age, sex, breed type and the test dose. The cohort included 149 horses, miniature horses, and ponies that had undergone an in-feed OGT and clin...
Barnabé MA, Elliott J, Harris PA, Menzies-Gow NJ.Equine metabolic syndrome is a collection of risk factors associated with an increased risk of endocrinopathic laminitis. All affected animals display insulin dysregulation and some may show adiponectin dysregulation and/or excessive adiposity. However, the relationship between obesity and hypoadiponectinaemia in equids remains unclear. Objective: To investigate the relationship between obesity and circulating plasma total adiponectin (TA) concentrations in native-breed ponies in England. Methods: Secondary data analysis. Methods: Data collected for three previous studies were retrospectively ...
Barnabé MA, Elliott J, Harris PA, Menzies-Gow NJ.The hormones insulin and adiponectin are commonly measured in equids because of their involvement in endocrinopathic laminitis. These are currently measured in serum/plasma, although jugular venipuncture can cause stress in some animals and may be impossible in needle-shy individuals. However, both hormones can be measured in saliva in other species. Objective: To determine whether [insulin] and [total adiponectin] are detectable in equine saliva using automated assays and whether saliva collection is associated with changes in stress indicators. Additionally, the correlation between serum and...
Hallman I, Tapio H, Raekallio M, Karikoski N.To assess the effects of an α-adrenoceptor agonist (detomidine) constant rate infusion (CRI) with and without an α-adrenoceptor antagonist (vatinoxan) CRI on blood insulin and glucose concentrations, heart rate, intestinal borborygmi, and sedation during and after infusion in horses. Methods: Randomized, blinded, crossover, experimental study. Methods: A total of nine healthy, adult Finnhorse mares. Methods: Horses were treated with an intravenous (IV) detomidine loading dose (0.01 mg kg), followed by CRI (0.015 mg kg hour), and the same doses of detomidine combined with an IV vatinoxan load...
Weckman MJ, Karikoski NP, Raekallio MR, Box JR, Kvist L.Equine metabolic syndrome (EMS) is a common welfare problem in horses worldwide. It is characterized by insulin dysregulation (ID), predisposition to laminitis and often obesity. EMS is multifactorial by nature, with both the environment and genetics contributing to the phenotype. Environmental factors, such as feeding and exercise, can be controlled, thus forming the basis for treatment and prevention. Genetic factors, by contrast, are less well-known and not easily controllable. The aim of this study was to identify potential genetic loci influencing ID/EMS in Finnhorses. A single-breed (Fin...
Qasem B, Dąbrowska A, Króliczewski J, Łyczko J, Marycz K.Equine metabolic syndrome (EMS) is a significant global health concern in veterinary medicine. There is increasing interest in utilizing molecular agents to modulate hepatocyte function for potential clinical applications. Recent studies have shown promising results in inhibiting protein tyrosine phosphatase (PTP1B) to maintain cell function in various models. In this study, we investigated the effects of the inhibitor Trodusquemine (MSI-1436) on equine hepatic progenitor cells (HPCs) under lipotoxic conditions. We examined proliferative activity, glucose uptake, and mitochondrial morphogenesi...
Johansson L, Ringmark S, Bergquist J, Skiöldebrand E, Jansson A.The plasma metabolomic profile of elite harness horses subjected to different training programmes was explored. All horses had the same training programme from 1.5 until 2 years of age and then high-intensity training was introduced, with horses divided into high and low training groups. Morning blood samples were collected at 1.5, 2, 2.5 and 3.5 years of age. The plasma was analysed using targeted absolute quantitative analysis and a combination of tandem mass spectrometry, flow-injection analysis and liquid chromatography. Differences between the two training groups were observed at 2 yea...
Kemp KL, Skinner JE, Bertin FR.Phenylbutazone is often prescribed to manage pain caused by hyperinsulinemia-associated laminitis, but in diabetic people nonsteroidal anti-inflammatory drugs increase insulin secretion and pancreatic activity. Objective: Investigate the effect of phenylbutazone administration on insulin secretion in horses. It was hypothesized that phenylbutazone will increase insulin secretion in horses with insulin dysregulation (ID). Methods: Sixteen light breed horses, including 7 with ID. Methods: Randomized cross-over study design. Horses underwent an oral glucose test (OGT) after 9 days of treatment ...
Hallowell KL, Dembek K, Horne CR, Knych HK, Messenger KM, Schnabel LV.Steroid-associated laminitis remains a major concern with use of corticosteroids in horses. Individual case factors such as joint pathology, pre-existing endocrinopathies, or corticosteroid type, dose, and timing influencing steroid-induced laminitis risk have not been investigated. This study aimed to determine if systemic absorption of triamcinolone acetonide (TA) varies between intrasynovial (antebrachiocarpal) and extrasynovial (sacroiliac) injection sites, and to determine the effects of TA absorption on glucose, insulin, cortisol, and adrenocorticotropic hormone (ACTH). Twenty adult hors...
Espinosa-López EM, Ortiz-Guisado B, Diez de Castro E, Durham A, Aguilera-Tejero E, Gómez-Baena G.Equine Metabolic Syndrome (EMS) is a multifactorial endocrine disorder characterized by obesity, insulin dysregulation (ID), and an increase in the risk of laminitis, a painful condition that can lead to euthanasia in severe cases. Diagnosing EMS is challenging and often relies on clinical history including obesity, difficulty in losing weight, and recurring episodes of laminitis. The gold standard for laboratory support of an EMS diagnosis is the identification of ID, with basal insulin being the simplest and most accessible method, especially in a field setting. However, various factors such...
Palm F, Nagel C, Bruckmaier RM, Aurich JE, Aurich C.Colostrum (COL) contains cytokines and growth factors that may enhance intestinal development in neonates. The hypothesis of this study was that besides providing immunoglobulins, COL is important for intestinal function and meconium release in foals. Newborn foals were either fed COL (n = 5) or an equal amount of milk replacer (MR, n = 7) during the first 24 hours of life. To ensure passive immunity, all foals received 1 L plasma. Postnatal development, meconium release, intestinal motility, white blood cell count, insulin-like growth factor 1, and intestinal absorptive function (xylose absor...
De La Corte FD, Valberg SJ, Mickelson JR, Hower-Moritz M.Polysaccharide storage myopathy (PSSM) in Quarter Horses (QH) and QH crosses is a glycogen storage disorder in which blood glucose clearance and insulin sensitivity, following an i.v. or oral glucose challenge, are enhanced. Exercise is known also to enhance glucose uptake into skeletal muscle in many animal species. Therefore, the purpose of this study was to compare the effect of exercise on glucose clearance in PSSM and control horses when an oral carbohydrate meal (8 Mcal sweet feed) was fed following either 12 h fasting alone (NEX protocol) or following fasting and a standard exercise pro...
Sweeney CR, Stebbins KE, Schelling CG, Beech J, Schilling DA.Hypertrophic osteopathy was diagnosed in a pony that had no antemortem or postmortem evidence of an intrathoracic lesion. With a history of hirsutism in an aged pony, a pituitary adenoma was suspected, and evaluation of plasma cortisol and insulin values and their response to thyrotropin-releasing hormone supported the diagnosis.
Sillence M, Meier A, de Laat M, Klee R, Reiche D.Although several studies have investigated factors associated with the onset and occurrence of hyperinsulinaemia-associated laminitis (HAL), few have examined the factors associated with the rate of improvement during recovery from an acute bout of the disease. This observational study sought to discover if a range of demographic, morphologic, hormonal and metabolic variables are associated with the improvement rate from HAL in 37 naturally-occurring cases identified by 16 clinics across Germany. Each case was evaluated for laminitis severity on the day of inclusion in the trial (d 0), then af...
Storer WA, Thompson DL, Waller CA, Cartmill JA.We previously reported that a rise in plasma leptin concentrations followed the rise in insulin and glucose in meal-fed horses, whereas horses maintained on pasture had little fluctuations in hormonal patterns. We have also described a hyperleptinemic-hyperinsulinemic condition that occurs in about 30% of our light horse mares of high body condition maintained on pasture. The present experiment was designed to 1) study the effect of 3 common feeding-housing regimens on leptin and other metabolic hormones in mares and 2) determine whether the hyperleptinemic condition interacted with these regi...
