Abstracts / Journal of Equine Veterinary Science 31 (2011) 230-356
glycemic response, insulin sensitivity and glucose-insulin dynamics in horses. Materials and Methods: Horses and Diets. Ten light horse type mares aged 4 to 17 with body condition scores ranging from 6 to 8 were paired according to age and body condition and randomly assigned to two groups. The control group (CON) received a commercial pelleted feed having DE of 3.30 Mcal/kg, and the treatment group (FISH) received the same pelleted feed plus ﬁsh oil having 14% EPA and 10% DHA (OmegaEquis, Omega Protein, Houston, TX), fed at 324 mg oil/kg BW, mixed into the feed. The concentrate portions of the CON and FISH groups were fed at a rate to supply 40% of the DE requirement of each horse, with hay supplying the remainder. Since the mares were used in the university riding program, DE requirements were determined based on body weight and a designation of light work throughout the study. Mares fed ﬁsh oil were fed slightly less pelleted feed so that DE intake/kg BW of the FISH group was isocaloric to the CON group. The menhaden oil was well accepted with no adverse effects. Supplementation continued for 60 days. Sample collection and analysis. Blood samples were collected every 6 days for plasma fatty acid analysis. A meal-related challenge was conducted on day 59 to determine the inﬂuence of diet on glycemic response. For the meal challenge, horses were fasted overnight with access to water. Jugular catheters were placed using aseptic technique and local anesthetic. Baseline samples were collected, and then the regular diets were fed to each horse, followed by sample collection every 15 min through 360 min after the meal. Frequently sampled intravenous glucose tolerance tests (FSIGT) were conducted on days 0 and 60 to assess effect of diet on insulin sensitivity . Plasma fatty acids were analyzed using gas chromatography. Blood glucose was analyzed using a glucometer previously validated for horses. Plasma insulin was analyzed using an EnymeLinked Immunosorbent Assay (Mercodia, Inc., Uppsala, Sweden), validated for equine insulin . Area under the curve (AUC) for meal-related glycemic response was calculated by graphical approximation. For estimation of insulin sensitivity in units commonly used for the minimal model of glucose dynamics, the insulin ELISA data (ug/L) were transformed to mU/L using the validation equation (r ¼ .97) in the companion paper . Insulin sensitivity (Si), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and the disposition index (DI) were calculated using MinMod Millennium and WinSAAM software. Statistical analysis. Data were tested for normality using the Shapiro-Wilk statistic. All data were normally distributed except for insulin sensitivity, which was transformed to its reciprocal in order to ﬁt a normal distribution for parametric analysis. Plasma fatty acids, meal-related glucose response, glucose AUC, baseline glucose and insulin, 1/Si, Sg, AIRg and DI were analyzed using a mixed model with repeated measures, with main effects of diet, horse and time. Diet and time were considered ﬁxed effects, and horse was considered a random effect. Results and Discussion: Over the 60 d period, FISH horses exhibited an increase (P < .01) in plasma EPA and DHA. Mealrelated glucose AUC were lower (P ¼.032) in horses fed FISH (45.7 7.84 g*min*L1) compared to the CON diet (77.4 9.03 g*min*L1). Basal glucose and insulin concentrations of FISH and CON horses were not different (P > .10). Insulin sensitivity, Sg, AIRg and DI of FISH and CON horses were not different (P > .10). Overall glucose clearance during the FSIGT was more rapid on day 60 than day 0 in both groups (P < .019). The increase in EPA and DHA concentrations over the 60 d period is consistent with previous reports . The lower glucose AUC in horses fed FISH compared to CON could be an effect of less feed, thus less starch, fed to the FISH group. Starch intakes were 0.88 and 1.13 g/kg BW and NSC intakes were 1.12 and 1.45 g/kg BW in
the FISH and CON meals, respectively. This difference alone was not enough to contribute to the signiﬁcant suppression in mealrelated glucose AUC , so the ﬁsh oil was likely a factor. Although workload did not increase, the more rapid glucose clearance on day 60 compared to day 0 in both groups may have been a training effect, as the horses were used in the university riding program. Conclusion: Supplementation of dietary ﬁsh oil increased plasma EPA and DHA while moderating blood glucose response to a concentrate meal, but it did not affect insulin sensitivity in normal horses. Acknowledgments: This project was supported in part by the STEP-MT undergraduate research program and the Mary E. Miller Chair of Excellence in Equine Health at MTSU. Menhaden oil was donated by OmegaEquis, Omega Protein, Houston, TX.
References  Huang T, Wahlqvist ML, Xu T, et al. Increased plasma n-3 unsaturated fatty acid is associated with improved insulin sensitivity in type 2 diabetes in China. Mol. Nutr. Food Res 2010;54(Suppl 1):S112-9.  O0 Connor CL, Lawrence LM, Hayes SH. Dietary ﬁsh oil supplementation affects serum fatty acid concentrations in horses. J. Anim. Sci 2007;85:2183-9.  Hoffman RM, Boston RC, Stefanovski D, et al. Obesity and diet affect glucose dynamics and insulin sensitivity in Thoroughbred geldings. J. Anim. Sci 2003;81:2333-42.  Kayser JP, Hoffman RM, Haffner JC, et al. Standardization of Equine Speciﬁc Enzyme-Linked Immunosorbent Assay for measuring serum insulin. J. Equine Vet. Sci; 2011. In press.  Hoffman RM, Haffner JC, Crawford CA, et al. Nonstructural carbohydrate and glycemic response of feeds: how low is 0 low0 starch? J. Equine Vet. Sci 2009;29:379-80.
The body condition score of leisure horses competing at an unafﬁliated championship in the UK I.J. Harker 1, P.A. Harris 2, and C.F. Barfoot 1 Mars HorseCare UK Ltd, Milton Keynes, Bucks, UK, 2 Equine Studies Group, Waltham Centre for Pet Nutrition, Melton Mowbary, Leics, UK 1
Introduction: Obesity is increasingly recognised as an equine welfare issue, and excessive weight may compromise both health and performance. In most instances horses become overweight because they are given the opportunity to consume calories in excess of their energy requirements. Certain breeds/types (e.g. cobs and native ponies) appear to be more prone to weight gain and therefore require even more careful management to try to prevent this energy imbalance from occurring. Evaluating body condition (BC), together with bodyweight, helps to assess and monitor the calorie intake of an individual horse relative to its own energy needs. A recent survey carried out in Scotland on pleasure riding horses reported that 45% were obese (i.e. 5 or 6 on authors' own 6 point scale) . It is therefore likely that owners are becoming increasingly accustomed to seeing overweight horses and may consider this to be the acceptable norm. This may be especially true with respect to animals within the pleasure section of the equine industry where many horses are not regularly exercised or competed. The objectives of this survey were to assess whether overweight animals also comprise a high proportion of the UK pleasure horses which are being regularly competed, and whether there is any inﬂuence of the competitive discipline. Materials and Methods: Horses and ponies were evaluated which had qualiﬁed via regional events to compete at the national
Abstracts / Journal of Equine Veterinary Science 31 (2011) 230-356
unafﬁliated championship show in a variety of equestrian disciplines (show jumping by senior riders [over 16 years of age], show jumping by junior riders [less than 17 years of age], dressage and showing (where judged when ridden and/or in hand halter for conformation, movement and condition etc.). A total of 331 horses and ponies ranging in size from 8-18hh with a mean height of 15.2hh and a mean age of 11 (ranging from 2-26 yrs) were condition scored over 10 days in July 2010. Horses were randomly assigned to one of a team of 6 trained assessors to be body condition scored (BCS) using a 1-9 system adapted from Henneke et al 1983 . Overall whole number scores were allocated to each horse based on descriptions and pictures. Horses were then categorised into binary variables based on BCS such that horses classiﬁed as having a BCS of 6 were considered to be overweight, a BCS of 7 as fat and a BCS of 8 as obese. Crosstabulations and chi-squared or Fishers exact tests were used to compare the proportions of horses overall and for the three binary categorisations (<8 vs 8, <7 vs 7 and <6 vs 6) among disciplines. Results are presented with P-values with the level of signiﬁcance set at P < .05 for all tests. Results and Discussion: Overall 62 percent of animals were categorised as being overweight, fat or obese, with a BCS >5, despite being in regular work and competing in this national championship. The distribution of BCS by discipline shows that there is a signiﬁcant difference among the different disciplines (overall chi-square test P ¼ .0002, Table 1). Using the cut-off for fat and obese horses (<7 vs 7), then dressage horses were fatter than senior show jumpers (P ¼ .03), show horses were fatter than senior show jumpers (P < .0001) and junior show jumpers were fatter than seniors (P ¼ .002). Finally, using the cut-off for overweight, fat and obese horses together (<6 vs 6), then show horses were fatter than dressage horses (P ¼ .045) which were fatter than senior show jumping horses (P ¼ .006) and junior show jumpers were fatter than seniors (P ¼ .002). Show horses were also fatter than senior show jumping horses (P < .0001). Conclusion: The fact that more show jumping horses being ridden by juniors had higher BCS than those ridden by seniors could reﬂect that a greater number of the animals ridden by juniors were of pony type (70% described as natives or native cross breeds vs. only 26% of senior show jumping horses being natives or native cross breeds). Perhaps not surprisingly the horses being shown were the most likely to be classiﬁed as overweight. This may reﬂect what is considered an 'ideal' BCS for this discipline. In addition, a proportion of classes in this discipline are not ridden which may make it difﬁcult for owners to achieve a ﬁt well muscled, conditioned horse without fat. Despite the increased focus on the dangers of obesity and the welfare implications, these survey results suggest that even in regularly exercised pleasure horses over half could be categorised as being overweight or fat. Therefore, further education is necessary to ensure horse owners are able to identify animals that are overweight and that they have the knowledge to adjust their Table 1 Distribution of BCS for horses within each equestrian discipline and overall BCS
<5 Ideal ¼ 5 Overweight ¼6 Fat ¼ 7 Obese 8 Total
Dressage (n ¼ 68)
Showing (n ¼ 80)
Show Jumping Juniors (n ¼ 97)
Show Jumping Seniors (n ¼ 86)
Overall (n ¼ 331)
4% 32% 44%
0% 21% 46%
1% 35% 40%
8% 51% 34%
3% 35% 41%
15% 5% 100%
25% 8% 100%
19% 5% 100%
7% 0% 100%
16% 5% 100%
feeding regimens in order to reach an ideal body condition score before clinical disease is seen. It may be valuable to undertake further research to identify what BCS owners of these competitive pleasure horses consider is the norm and acceptable.
References  Wyse CA, McNie KA, Tannahil VJ, et al. Prevalence of obesity in riding horses in Scotland. Vet Rec 2008;162:590-1.  Henneke DR, Potter GD, Krieder JL, Yeates. Relationship between condition score, physical measurements and body fat percentage in mares. Equine Vet J 1983;15:371-2.
Evaluation of the safety and performance of an enteral diet formulated speciﬁcally for horses K.R. Vineyard, M.E. Gordon, K.K. Williamson, and M.L. Jerina Land O'Lakes Purina Feed, Gray Summit, Missouri, USA Introduction: Information and studies that address the enteral delivery of nutrients for the sick and/or inappetent horse is limited1,2,3. A series of experiments were conducted to assess the relative safety and performance of a low soluble carbohydrate, ﬁber-rich enteral formulation (Wellsolve Well-GelÒ) intended to provide nutritional support for hypophagic horses. Materials and Methods: A series of three experiments and one ﬁeld trial were conducted during the development of this equinespeciﬁc enteral formula (EF) (36% CP, 6% fat, 14% max ﬁber, 4% starch, 7% sugar), formulated to meet 100% of NRC requirements for protein, vitamins, and minerals when supplied at a rate of 0.3% BW/d. In Experiment 1, 4 mature horses received either 0.45 kg of a ration balancer (Enrich 32Ò) or an isoenergetic amount of hydrated EF (2:1 water:EF) offered for voluntary consumption once daily. Horses also received approximately 1.5% BW in grass hay/d. After a 6 d acclimation period, horses were catheterized on d 7 and blood was collected prior to the meal and at 15-min intervals for 120 min and analyzed for total serum and plasma protein and hematocrit. Differences between treatments were analyzed using the Student's t-test and considered signiﬁcant at P < .05. In experiment 2, 8 mature horses received 1.8-2.3 kg of hydrated EF (1:1 water:EF) divided into 2 daily feedings for voluntary consumption for 30 d. An additional 4 horses were enterally administered 0.45 kg of hydrated EF (3:1 water:EF) twice daily for 5 d. Horses also received approximately 1.5% BW in grass hay/d. General horse health (manure consistency, signs of colic, gastric disturbance) was recorded daily throughout the experiment. In experiment 3, eight mature horses were assigned to one of two dietary treatments in a replicated 4x4 Latin Square design: 0.45 kg of hydrated EF (1:1 water:EF) offered for voluntary consumption (treatment A) or .45 kg of hydrated EF (3:1 water:EF) administered enterally (treatment B). Horses were fed a basal concentrate ration (StrategyÒ) along with approximately 1.5% BW in grass hay/d for 6 d. On d 7 horses were catheterized and blood was collected prior to treatment administration and at 30-min intervals for 360 min. Blood was analyzed for glucose, insulin, triglycerides and non-esteriﬁed fatty acids (NEFA). Differences between treatments were analyzed using PROC MIXED with repeated measures in SAS (SAS Inst. Inc., Cary, NC) and considered signiﬁcant at P < .05. In the ﬁeld trial, over 500 kg of the EF was shipped to selected veterinary hospitals across the United States (n ¼ 11) to be utilized over a 9-month period. Clinicians were asked to complete a detailed survey for each patient that was administered the EF and to evaluate the product's overall performance. Results and Discussion: Although speciﬁc information regarding nutritional requirements of the critically ill horse is limited,