Laminitis and the Equine Metabolic Syndrome

Abstract

Although much has been written about laminitis in the context of its association with inflammatory processes, such as dietary carbohydrate overload and endotoxemia, [1][2][3][4][5] recognition is growing that most cases of laminitis examined by veterinarians in private practice are those associated with pasture grazing, obesity, and insulin resistance (IR). 6,7 The term endocrinopathic laminitis has been adopted to classify the instances of laminitis in which the origin seems to be more strongly associated with an underlying endocrinopathy, such as either IR or the influence of corticosteroids. [8][9][10][11] Results of a recent study suggest that obesity and IR represent the most common metabolic and endocrinopathic predispositions for laminitis in horses. 6,12 IR also plays an important role in the pathogenesis of laminitis that develops when some horses or ponies are allowed to graze pastures at certain times of the year (pasture-associated laminitis [PAL]). [12][13][14][15] Moreover, IR is provoked by and contributes to pathophysiologic processes associated with endotoxemia and systemic inflammation under the more classic circumstances associated with risk for acute laminitis, such as grain overload, retention of fetal membranes, and gastroenteritis. 16,17 However, a recent study using the oligofructose model showed that experimentally induced laminitis was not associated with a loss of insulin sensitivity. 18 The term equine metabolic syndrome (EMS) has been proposed as a label for horses whose clinical examination results (including both physical examination and laboratory testing) suggest heightened risk for developing laminitis as a result of underlying IR. 19 EMS is not a disease per se, but rather is a clustering of clinical abnormalities that, when identified collectively in a given patient, indicates that the likelihood of developing laminitis is greater than in individuals lacking the EMS criteria. Use of the term EMS is especially practical for distinguishing affected horses from those affected with either Cushing's (pituitary pars intermedia dysfunction [PPID]) or hypothyroidism, with which EMS is often confused. 19 The clinical importance of diagnosing EMS centers on the fact that recognized risk factors for laminitis can subsequently be avoided in the affected individual. Preventive measures aimed at reducing the risk for laminitis should be rigorously emphasized in EMS-affected horses and ponies.Recently, the American College of Veterinary Internal Medicine (ACVIM) commissioned a panel of EMS-interested specialists to develop a consensus statement that would help define the syndrome based on current knowledge. 20 During development of the consensus statement, contents of the working draft were presented and discussed at the ACVIM Annual Forum in Montreal, Canada and some of the following comments will be based on those discussions. 20 Ongoing experimental and clinical studies will help better define EMS (which is distinctly different to the human metabolic syndrome 21 ) in the next few years. D...

Diabetes, Insulin Resistance, and Metabolic Syndrome in Horses

“…In contrast, the interstitial glucose concentration of obese horses in which IR has been demonstrated using CGIT tends to be more variable over time, runs relatively high within the reference range, and frequently exceeds the high end of the reference range. 55 We have also demonstrated that, when undertaken at the same time as a standard CGIT, there is very high correlation and concordance between results for both methods. clinical circumstances.…”

“…Dietary adjustments must strive to deliver a ration that is characterized by a low NSC content (low glycemic index) in order to both address obesity and minimize phases of hyperinsulinemia that are exacerbative to the laminitic condition. 55,61 As is the case in other species, dietary management represents a very important component of treatment of both IR and DM in horses. The optimal diet for management of DM in horses is unknown, but a low glycemic ration characterized by high fiber content, low NSCs, and added calories in the form of fat is regarded as a logical choice.…”

“…If EMS is diagnosed before painful laminitis has occurred, the following preventive strategies are generally recommended: reversal of obesity (when applicable) through both dietary change and increased physical activity; dietary change aimed at reducing the glycemic index of the ration; increased level of physical activity; avoidance of pasture grazing for susceptible individuals (pastures represent an important source of NSCs), especially at certain times of the year and times of the day; and the initiation of critical evaluations of the patient's hoof (based on appearance and radiographic characteristics), with a view to promoting hoof care practices (farriery) that should reduce the risk of laminitis. 55 Unfortunately, when EMS is diagnosed after painful laminitis has occurred, the application of increased physical activity is not possible because it leads to the worsening of damage in the hoof-lamellar interface. In these cases, treatment of laminitis must be based on critical evaluations of the patient's hoof (after reviewing the appearance and radiographic characteristics of the hoof).…”

“…40,65 Increased levels of exercise are strongly recommended for horses affected with EMS and IR. [1][2][3]55 Dietary supplementation using levothyroxine sodium is commonly recommended to promote weight loss and to increase insulin sensitivity. 2,3 The use of certain insulinsensitizing drugs as a component of the management of IR is beginning to gain acceptance in some cases.…”

Atlarda Metabolik Sendrom (EMS) Sancısında, Adipoz Dokuda ve Periferal Kanda IL-6 ve TNF-α nın Aktivitesi

“…For the determination of glucose level by means of glucometer (Glucosens 1040), blood samples were collected at 1, 5, 15, 25, 35, 45 , 60, 75 , 90, 105, 120, 135 and 150 minutes after administration of a bolus. In total, blood samples were collected for 2.5 h [13,26,27] . Sterile technique was maintained throughout the collection process.…”