Equine Studies Group

Stoke-on-Trent, United Kingdom

Equine Studies Group

Stoke-on-Trent, United Kingdom
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Bamford N.J.,University of Melbourne | Potter S.J.,University of Melbourne | Harris P.A.,Equine Studies Group | Bailey S.R.,University of Melbourne
Equine Veterinary Journal | Year: 2016

Reasons for performing study: The relative influences of obesity and adaptation to high glycaemic diets on the development of insulin dysregulation in equids are unclear. Objectives: To determine whether increased adiposity per se is responsible for the decreased insulin sensitivity often observed in obese horses or whether a dietary glycaemic response is critically important. Study design: Randomised controlled trial. Methods: Eighteen horses and ponies were studied over a 20-week period. They received ad libitum hay plus either a high fat (low glycaemic) diet (FAT; n = 6) or a similar (isocaloric) diet containing 1.5 g/kg bwt once daily glucose (GLU; n = 6) to induce obesity. A third group received a control ration (CON; n = 6). Adiposity was monitored using body condition score (BCS) and total body fat mass percentage (TBFM) determined using a deuterium oxide dilution technique. Insulin sensitivity was assessed using a frequently sampled i.v. glucose tolerance test. Plasma concentrations of glucose, insulin, leptin, adiponectin, tumour necrosis factor-α (TNF-α) and serum amyloid A (SAA) were measured. Results: The FAT and GLU groups became obese (BCS ≥7) whereas the CON group maintained moderate condition (BCS ≤6). Total body fat mass and leptin concentrations were increased in the FAT and GLU groups than in the CON group (P<0.001 and P = 0.003, respectively). Values for both insulin-dependent (SI) and insulin-independent (Sg) glucose disposal were higher in the GLU group compared with the FAT and CON groups (P = 0.006 and P = 0.03, respectively). There were no differences in adiponectin, TNF-α or SAA between groups (all P≥0.4). Conclusions: Increased adiposity did not reduce insulin sensitivity in either the FAT or the GLU diet groups, suggesting that obesity per se might not be responsible for the lower SI values reported in previous studies. Contrary to expectations, once daily glucose appeared to increase insulin sensitivity. Further work is required into the dietary causes of insulin resistance in equids. © 2016 EVJ Ltd.


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

Reasons for performing study: Evaluation of equine body fat content is important for nutritional and clinical purposes. However, our understanding of total body fat and its regional distribution in the body is sparse. Currently, body fat evaluation relies on the subjective assessment of body condition score (BCS), which has never been validated against 'gold standard' chemical analysis or dissection measurements in ponies. Objectives: To define the relationships between subjective (BCS), objective (morphometric) indices of body fat and 'gold standard' measurements of actual body composition. Hypotheses: BCS and morphometry offer valid, noninvasive methods for determination of body fat in equids. Methods: Seven mature (mean ± s.e. 13 ± 3 years, 212 ± 14kg, BCS 1.25-7/9), Welsh Mountain pony mares, destined for euthanasia (for nonresearch purposes), were used. For all ponies, body mass (BM), BCS and various morphometric measurements were recorded. Following euthanasia, all ponies were systematically dissected. Discrete white adipose tissue (WAT) depots were independently described. Gross, body chemical composition was determined by proximate analyses. Results: Total somatic soft tissues increased linearly (r 2= 1.00), whereas body WAT content (1-26% live BM) increased exponentially (r 2= 0.96), with BCS. WAT was equally distributed between internal and external sites in all animals irrespective of BCS. Nuchal fat was a poor predictor of total WAT (r 2= 0.66). Periorbital WAT did not alter with BCS (r 2= 0.01). Heart girth:withers height and ultrasonic retroperitoneal fat depth were closely associated with total, chemically-extracted lipid which comprised 1-29% live BM (r 2= 0.91 and 0.88, respectively). Conclusions and potential relevance: The exponential relationship between BCS and total body WAT/lipid suggests that BCS is unlikely to be a sensitive index of body fat for animals in moderate-obese states. Morphometric measurements (body girths and retroperitonel fat depth) may be useful to augment subjective BCS systems. © 2011 EVJ Ltd.


Longland A.C.,ELNS | Dhanoa M.S.,Rothamsted Research | Harris P.A.,Equine Studies Group
Journal of the Science of Food and Agriculture | Year: 2012

Background: Pasture (fresh or conserved as hay/haylage) forms the basis of most equid diets and contains varying amounts (0 to ≥ 200 g kg -1 dry matter (DM) or more) of fructans. Over-consumption of fructan is associated with the onset of laminitis in equids, an agonizing condition that may necessitate euthanasia. To enable appropriate dietary management of animals susceptible to laminitis, it is essential that fructans can be properly quantified in fresh and conserved pasture. For research purposes, fructans are frequently quantified by high-performance liquid chromatography (HPLC), but these methods are costly for routine screening. However, an inexpensive colorimetric method for measuring fructans in human foods is commercially available. The aim here was to determine the suitability of the commercially available colorimetric method for determining the fructan content of pasture grasses for horses. Results: Pasture grasses (Phleum pretense, Festuca rubra, Dactylis glomerata, Lolium perenne) managed for grazing (sampled from April to November) and a further set managed for conservation (sampled in July) were analysed for fructan content by HPLC and the colorimetric technique. HPLC values ranged from 83 to 299 g fructan kg -1 DM (mean 154); corresponding colorimetric values were 5-238 g fructan kg -1 DM (mean 82). Discrepancies in values between the two methods varied with time of sampling and plant species. Comparison of selected samples before and after incubation with the fructan hydrolases used in the colorimetric method revealed incomplete fructan hydrolysis from the pasture grasses, resulting in underestimates of their fructan content. Conclusion: The colorimetric technique was not a reliable substitute for HPLC to quantify the fructan content of pasture grasses. © 2012 Society of Chemical Industry.


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.


Tinworth K.D.,Charles Sturt University | Boston R.C.,University of Pennsylvania | Harris P.A.,Equine Studies Group | Sillence M.N.,Queensland University of Technology | And 2 more authors.
Veterinary Journal | Year: 2012

Metformin may be an effective therapeutic option for insulin-resistant (I-R) horses/ponies because, in humans, it reportedly enhances insulin sensitivity (SI) of peripheral tissues without stimulating insulin secretion. To determine the effect of metformin on insulin and glucose dynamics in I-R ponies, six ponies were studied in a cross-over design by Minimal Model analysis of a frequently-sampled intravenous glucose tolerance test (FSIGT). Metformin was administered at 15. mg/kg bodyweight (BW), orally, twice-daily, for 21. days to the metformin-treated group. The control group received a placebo. A FSIGT was conducted before and after treatment. The Minimal Model of glucose and insulin dynamics rendered indices describing SI, glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and the disposition index (DI). The body condition score (BCS), BW and cresty neck score (CNS) were also assessed. There was no significant change in SI, Sg, AIRg, DI, BW, BCS or CNS in response to metformin, or over time in the control group. There were no measurable benefits of metformin on SI, consistent with recent work showing that the bioavailability of metformin in horses is poor, and chronic dosing may not achieve therapeutic blood concentrations. Alternatively, metformin may only be effective in obese ponies losing weight or with hyperglycaemia. © 2011 Elsevier Ltd.


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.


Dugdale A.H.A.,University of Liverpool | Curtis G.C.,University of Liverpool | Cripps P.,University of Liverpool | Harris P.A.,Equine Studies Group | Argo C.M.,Equine Studies Group
Equine Veterinary Journal | Year: 2010

Reasons for performing study: Increased prevalence of obesity among UK horses and ponies demands evidence-based advice to promote weight loss. Hypothesis: Restriction of dry matter intake (DMI) to 1% of body mass (BM, 6% of predicted maintenance digestible energy [DE] requirements) would promote weight loss without compromise to health. Methods: Five mature (mean ± s.e. 10 ± 2 years), overweight/obese pony mares (BM, 257 ± 20 kg: body condition score [BCS] 6.8/9 ± 0.5) were studied over 12 weeks. Animals were individually housed. Daily provision of a chaff-based, complete diet (measured DE, 8.5 MJ/kg DM) was restricted to 1% of actual BM as DMI daily. BCS, girth measurements and ultrasound-derived measures of subcutaneous fat depth overlying the gluteal region and 12th intercostal space (rib-eye) were recorded weekly. Body fat content was estimated at the beginning and end of the study by deuterium oxide dilution methods. Clinical biochemistry was monitored weekly. Behaviour was observed (24 h, 3/5 ponies) on 3 occasions. Results: BM decreased by 4.3 ± 1.1% during the first week and thereafter by 0.7 ± 0.1% of BM at end of Week 1 each week. BCS remained constant. Heart and belly girths, rump width and subcutaneous fat depth at rib-eye decreased significantly with time and BM. Fat comprised 45 ± 19% of BM loss. Fatter animals lost relatively more fat. With decreased feeding activity, time spent in 'play' and rest increased by 36 ± 11% and 438 ± 95%, respectively. Conclusions: This plane of nutrition resulted in an overall rate of weight loss of 1% of outset BM weekly. BCS was not a useful index of early weight loss but heart and belly girths and subcutaneous rib-eye fat were identified as alternative markers. Potential relevance: This study provides an evidence-base for the management of weight loss in obese animals, especially those for which exercise may be contra-indicated. © 2010 EVJ Ltd.


Dougal K.,Aberystwyth University | de la Fuente G.,Aberystwyth University | Harris P.A.,Equine Studies Group | Girdwood S.E.,Aberystwyth University | And 2 more authors.
PLoS ONE | Year: 2013

The horse has a rich and complex microbial community within its gastrointestinal tract that plays a central role in both health and disease. The horse receives much of its dietary energy through microbial hydrolysis and fermentation of fiber predominantly in the large intestine/hindgut. The presence of a possible core bacterial community in the equine large intestine was investigated in this study. Samples were taken from the terminal ileum and 7 regions of the large intestine from ten animals, DNA extracted and the V1-V2 regions of 16SrDNA 454-pyrosequenced. A specific group of OTUs clustered in all ileal samples and a distinct and different signature existed for the proximal regions of the large intestine and the distal regions. A core group of bacterial families were identified in all gut regions with clear differences shown between the ileum and the various large intestine regions. The core in the ileum accounted for 32% of all sequences and comprised of only seven OTUs of varying abundance; the core in the large intestine was much smaller (5-15% of all sequences) with a much larger number of OTUs present but in low abundance. The most abundant member of the core community in the ileum was Lactobacillaceae, in the proximal large intestine the Lachnospiraceae and in the distal large intestine the Prevotellaceae. In conclusion, the presence of a core bacterial community in the large intestine of the horse that is made up of many low abundance OTUs may explain in part the susceptibility of horses to digestive upset. © 2013 Dougal et al.


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.


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.

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