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Waltham on the Wolds, United Kingdom

Tinworth K.D.,Charles Sturt University | Harris P.A.,Equine Studies Group | Sillence M.N.,Queensland University of Technology | Noble G.K.,Charles Sturt University
Veterinary Journal | Year: 2010

Insulin resistance and hyperinsulinaemia increase the risk of laminitis and horse owners and veterinarians should attempt to enhance insulin sensitivity in at-risk groups. In obese animals this may be achieved, in part, by promoting weight loss and increasing exercise, but such intervention may not be appropriate in non-obese insulin-resistant animals, or where exercise is contra-indicated for clinical reasons. An alternative approach to controlling insulin sensitivity in obese and non-obese horses may be the use of certain herbal compounds that have shown promise in humans and laboratory animals, although little is known of the effects of these compounds in horses. The herbs can be grouped according to their primary mechanism of action, including activators of the peroxisome proliferator-activated receptors, anti-obesity compounds, anti-oxidants, compounds that slow carbohydrate absorption, insulin receptor activators and stimulators of glucose uptake, with some herbs active in more than one pathway. Certain herbs have been prioritised for this review according to the quality and quantity of published studies, the reported (or extrapolated) safety profile, as well as potential for efficacy, all of which will hopefully motivate further research in this field. © 2009 Elsevier Ltd. Source

Dugdale A.H.A.,University of Liverpool | Curtis G.C.,University of Liverpool | Cripps P.J.,University of Liverpool | Harris P.A.,Equine Studies Group | Argo C.M.,University of Liverpool
Veterinary Journal | Year: 2011

Changes in appetite, body mass (BM), body condition score (BCS), direct (ultrasonographic) and indirect (deuterium oxide dilution technique) measures of body fat were monitored in Welsh Mountain pony mares (. n=. 11, 5-19. years of age) offered ad libitum access to a complete diet (gross energy 16.9. ±. 0.07. MJ/kg dry matter) for 12. weeks during summer (. n=. 6; 246. ±. 20. kg) and winter (. n=. 5; 219. ±. 21. kg). At the outset, each group comprised two thin (BCS 1-3/9), moderate (BCS 4-6/9) and obese (BCS 7-9/9) animals.For ponies that were non-obese at the outset, BM was gained more rapidly (. P=. 0.001) in summer (0.8. ±. 0.1. kg/day) than winter (0.6. ±. 0.0. kg/day). This was associated with a seasonal increase in dry matter intake (DMI) which became maximal (summer, 4.6. ±. 0.3% BM as DMI/day; winter, 3.5. ±. 0.1% BM as DMI/day) during the second month. The appetite of the obese ponies was half that reported for non-obese animals in the summer and BM remained constant irrespective of season.Body 'fatness' increased progressively for non-obese but not obese ponies. Body fat content was exponentially associated with increasing BCS but BCSs >6 were not useful indicators of actual body fat. Endogenous circannual mechanisms to suppress winter weight gain were insufficient to prevent the development of obesity in ad libitum fed ponies. © 2010 Elsevier Ltd. Source

Bamford N.J.,University of Melbourne | Potter S.J.,University of Melbourne | Harris P.A.,Equine Studies Group | Bailey S.R.,University of Melbourne
Domestic Animal Endocrinology | Year: 2014

Breed-related differences may occur in the innate insulin sensitivity (SI) of horses and ponies, an important factor believed to be associated with the risk of laminitis. The aim of this study was to measure the glucose and insulin responses of different breeds of horses and ponies in moderate body condition to a glucose-containing meal and to compare these responses with the indices of SI as determined by a frequently sampled intravenous glucose tolerance test (FSIGT). Eight Standardbred horses, 8 mixed-breed ponies, and 7 Andalusian-cross horses with a mean ± SEM BCS 5.0 ± 0.3 of 9 were used in this study. Each animal underwent an oral glucose tolerance test (OGTT) in which they were fed a fiber-based ration (2.0 g/kg BW) containing 1.5 g/kg BW added glucose, as well as a standard FSIGT with minimal model analysis. The glucose response variables from the OGTT were similar between groups; however, the peak insulin concentration was higher in ponies (94.1 ± 29.1 μIU/mL; P = 0.003) and Andalusians (85.3 ± 18.6; P = 0.004) than in Standardbreds (21.2 ± 3.5). The insulin area under the curve was also higher in ponies (13.5 ± 3.6 IU·min·L-1; P = 0.009) and Andalusians (15.0 ± 2.7; P = 0.004) than in Standardbreds (3.1 ± 0.6). Insulin sensitivity, as determined by the FSIGT, was lower in Andalusians (0.99 ± 0.18 × 10-4/[mIU·min]) than in Standardbreds (5.43 ± 0.94; P < 0.001) and in ponies (2.12 ± 0.44; P = 0.003) than in Standardbreds. Peak insulin concentrations from the OGTT were negatively correlated with SI (P < 0.001; rs = -0.75). These results indicate that there are clear breed-related differences in the insulin responses of horses and ponies to oral and intravenous glucose. All animals were in moderate body condition, indicating that breed-related differences in insulin dynamics occurred independent of obesity. © 2014 Elsevier Inc. Source

Argo C.M.C.G.,University of Liverpool | Curtis G.C.,University of Liverpool | Grove-White D.,University of Liverpool | Dugdale A.H.A.,University of Liverpool | And 2 more authors.
Veterinary Journal | Year: 2012

Evidence-based, weight loss management advice is required to address equine obesity. Changes in body mass (BM), body condition score (BCS), heart (HG) and belly circumference (BG), direct (ultrasonographic) and indirect (D2O dilution, bioelectrical impedance analysis [BIA]) measures of body fat as well as indices of insulin resistance (IR) were monitored in 12 overweight (BCS≥7/9) horses and ponies of mixed breed and gender for 16weeks. Animals were randomly assigned to two groups (Group 1, n=6, BCS 7.6/9±0.6, 489±184.6kg; Group 2, n=6, BCS 8.1/9±0.6, 479±191.5kg). Daily dry matter intake (DMI) was restricted to 1.25% BM as one of two, near-isocaloric (DE ∼0.115MJ/kgBM/day), forage-based diets (Group 1, 0.8% BM chaff-based feed: 0.45% BM hay; Group 2, 1.15% BM hay: 0.1% BM nutrient-balancer).Statistical modelling revealed considerable between-animal heterogeneity in proportional weight losses (0.16-0.55% of Week 1 BM weekly). The magnitude of weight loss resistance (WLR) or sensitivity to dietary restriction was independent of diet or any measured outset variable and was largely (65%) attributed to animal identity. Predicted rates of weight loss decreased over time. BCS and BIA were poor estimates of D2O-derived body fat%. Reciprocal changes in depths of retroperitoneal and subcutaneous adipose tissues were evident. Changes in BG were associated with losses in retroperitoneal fat and BM (r2, 0.67 and 0.79). Indices of IR improved for 9/12 animals by Week 16. For obese animals, weight loss should be initiated by restricting forage DMI to 1.25% BM. Subsequent restriction to 1% BM may be warranted for WLR animals. © 2012 Elsevier Ltd. Source

Dugdale A.H.A.,University of Liverpool | Grove-White D.,University of Liverpool | Curtis G.C.,University of Liverpool | Harris P.A.,Equine Studies Group | Argo C.M.C.G.,University of Liverpool
Veterinary Journal | Year: 2012

Body condition scoring systems were originally developed to quantify flesh cover in food animals and are commonly used to evaluate body fat in Equidae. The relationship between concurrent estimates of body fat content (eTBF%, deuterium oxide dilution; range, 2.7-35.6%) and subjective appraisals of body 'fatness' (body condition score, BCS; range, 1.25-9/9), was investigated in 77 mature horses and ponies. Univariate (UVM, r2=0.79) and multivariable (MVM, r2=0.86) linear regression models described the association, where BCS and eTBF% were explanatory and outcome variables, respectively. Other measures (age, sex, breed, body mass, ultrasound-generated subcutaneous and abdominal retroperitoneal fat depths, withers height, heart and belly circumferences) were considered as potential confounders but only height, belly circumference and retroperitoneal fat depth remained in the final MVM.The association between BCS and eTBF% was logarithmic. Appraisal of the transformed regression (UVM), actual eTBF% values and 95%CIs of the model forecast, suggested that the power of log-transformed BCS as a predictor of eTBF% decreased as BCS increased. The receiver operating characteristic curve for the prediction of horses with an eTBF% of >20%, suggested that the UVM correctly classified 76% of horses using a 'cut-off' of BCS 6.83/9 (sensitivity, 82.5%; specificity, 70.8%). Negative values for eTBF% were obtained for two thin ponies which were excluded from analyses, and caution is advised in the application of deuterium dilution methodologies where perturbed tissue hydration could be predicted. The data suggest that BCS descriptors may warrant further consideration/refinement to establish more clinically-useful, sub-classifications for overweight/obese animals. © 2012 Elsevier Ltd. Source

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