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The quadrennial International Conference on Equine Exercise Physiology (ICEEP) allows focused presentations of a variety of horse exercise- and performance-related research data in cardiorespiratory, muscle, biomechanics, nutrition, genomics, and applied physiology. The most diverse section of the ICEEP meeting has been termed variously 'Applied Exercise Physiology' (ICEEP 8 and 9), 'Applied Physiology: Training Methods, Exercise Testing and Selection' (ICEEP 7), or 'Applied Physiology of Athletic Performance' (ICEEP 6 and earlier). The next ICEEP meeting is scheduled to be held in Australia in 2018. In this subspeciality of equine exercise physiology, scientists attempt to apply or put into practical field use the techniques and tools developed in the more basic sciences in order to assess the performance, training, and injury of horses working and performing under true, non-laboratory conditions. The real test of the value of this subspeciality will be the increased application and sustainability of the use of laboratory techniques in the assessment of equine athletes in field settings. This review summarises exercise physiology findings prior to the widespread use of equine laboratory treadmills which have tethered investigators to the laboratory, and explains and illustrates newer, more portable, often digital technological developments which have allowed investigations to move out of the laboratory and back to the field setting where horses train and compete on a daily basis. [ABSTRACT FROM AUTHOR]

OBJECTIVE To determine cardiorespiratory responses of Thoroughbreds to uphill and downhill locomotion on a Treadmill at identical gradients. ANIMALS 5 highly trained Thoroughbred geldings. PROCEDURES Thoroughbreds were exercised for 2-minute intervals on a treadmill at 1.7, 3.5, 6.0, 8.0, and 10.0 m/s at a 4% incline, 0% incline (horizontal plane), and 4% decline in random order on different days. Stride frequency, stride length, and cardiopulmonary and 02-transport variables were measured and analyzed by means of repeated-measures ANOVA and Holm-Sidak pairwise comparisons. Horses completed all treadmill exercises with identical stride frequency and stride length. At identical uphill speeds, they had higher (vs horizontal) mass-specific 02 consumption (mean increase, 49%) and C02 production (mean increase, 47%), cardiac output (mean increase, 21%), heart rate (mean increase, 11%), and Paco2 (mean Increase, 1.7 mm Hg), and lower Paoi (mean decrease. 5.8 mm Hg) and arterial Q2 saturation (mean decrease, 1.0%); tidal volume was not higher. Downhill locomotion (vs horizontal) reduced mass-specific 02 consumption (mean decrease, 24%), C02 production (mean decrease, 23%), and cardiac output (mean decrease. 9%). Absolute energy cost during uphill locomotion increased linearly wirh speed at approximately twice the rare at which it decreased during downhill locomotion. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that for Thoroughbreds, downhill locomotion resulted in a lower energy cost than did horizontal or uphill locomotion and that this cost changed with speed. Whether eccentric training induces skeletal muscle changes in horses similar to those in humans remains to be determined. [ABSTRACT FROM AUTHOR]

Dynamic upper respiratory tract ( URT) obstructions occur commonly in the equine athlete. During the past 25 years, veterinary diagnostic capabilities have improved greatly with the ability to perform endoscopy during exercise and thus to visualise upper airway function during various types of exercise. After correctly reproducing and diagnosing an URT obstruction, the veterinary surgeon must consider the functional significance of the endoscopic findings for that individual athlete. This is the third paper in this series and focuses on the diagnosis of URT obstructions, their relationship to the exercise test and their functional significance. [ABSTRACT FROM AUTHOR]

Recent studies performed in humans and rats have reported that exercise can alter the intestinal microbiota. Athletic horses perform intense exercise regularly, but studies characterizing horse microbiome during aerobic conditioning programs are still limited. Evidence has indicated that this microbial community is involved in the metabolic homeostasis of the host. Research on ergogenic substances using new sequencing technologies have been limited to the intestinal microbiota and there is a considerable demand for scientific studies that verify the effectiveness of these supplements in horses. L-carnitine and chromium are potentially ergogenic substances for athletic humans and horses since they are possibly able to modify the metabolism of carbohydrates and lipids. This study aimed to assess the impact of acute exercise and aerobic conditioning, associated either with L-carnitine or chromium supplementation, on the intestinal microbiota of fillies. Twelve “Mangalarga Marchador” fillies in the incipient fitness stage were distributed into four groups: control (no exercise), exercise, L-carnitine (10g/day) and chelated chromium (10mg/day). In order to investigate the impact of acute exercise or aerobic conditioning on fecal microbiota all fillies undergoing the conditioning program were analyzed as a separate treatment. The fillies underwent two incremental exercise tests before and after training on a treadmill for 42 days at 70–80% of the lactate threshold intensity. Fecal samples were obtained before and 48 h after acute exercise (incremental exercise test). Bacterial populations were characterized by sequencing the V4 region of the 16S rRNA gene using the MiSeq Illumina platform, and 5,224,389 sequences were obtained from 48 samples. The results showed that, overall, the two most abundant phyla were Firmicutes (50.22%) followed by Verrucomicrobia (15.13%). The taxa with the highest relative abundances were unclassified Clostridiales (17.06%) and "5 genus incertae sedis" from the phylum Verrucomicrobia (12.98%). There was a decrease in the phylum Chlamydiae and in the genus Mycobacterium after the second incremental exercise test. Intense exercise changed the community’s structure and aerobic conditioning was associated with changes in the composition and structure of the intestinal bacterial population of fillies. The intra-group comparison showed that chromium or L-carnitine induced moderate changes in the fecal microbiota of fillies, but the microbiota did not differ from the control group, which was exercised with no supplementation. Fecal pH correlated positively with Simpson’s index, while plasma pH correlated negatively. Our results show that exercise and aerobic conditioning can change in the microbiota and provide a basis for further studies enrolling a larger number of horses at different fitness levels to better understand the effects of exercise and training on the intestinal microbiota of horses. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To analyze the effects of vertical force peak (VFP) of repition within trials and between trial sessions in horses with naturally occurring appendicular lameness. ANIMALS: 20 lame horses acclimated to trotting over a force plate. PROCEDURES: Kinetic gait data were collected by use of a force plate regarding affected and contralateral limbs of lame horses that completed 5 valid repetitions in each of 5 sessions performed at 0,3,6, 12, and 24 hours, constituting I trial/horse. Data were compared within and among repetitions and sessions, and factors influencingVFP values were identified. RESULTS: VFP values differed for lame limbs after 3 valid repetitions were performed within a session and when the interval between sessions was 3 hours. Direction of change reflected less lameness (greater VFP). Lamer horses (≥ grade 4/5) had this finding to a greater degree than did less lame horses. Results were similar for contralateral limbs regarding valid repetitions within a session; however,VFP decreased when the interval between sessions exceeded 6 hours. The coefficient of variation forVFP was ≤ 8% within sessions and < 6% between sessions. The asymmetry index forVFP did not change throughout the study. CONCLUSIONS AND CLINICAL RELEVANCE: Lameness profiles obtained through kinetic gait analysis of horses with naturally occurring lameness were most accurate when valid repetitions were limited to 3 and the interval between sessions within a trial was > 3 hours. Findings suggested that natural lameness may be as suitable as experimentally induced lameness for lameness research involving horses [ABSTRACT FROM AUTHOR]

Background Prolonged exercise in human athletes is associated with transient impairment of left ventricular ( LV) function, known as cardiac fatigue. Cardiac effects of prolonged exercise in horses remain unknown. Objectives To investigate the effects of prolonged exercise on LV systolic and diastolic function in horses. Animals Twenty-six horses competing in 120-160 km endurance rides. Methods Cross-sectional field study. Echocardiography was performed before and after rides, and the following morning, and included two-dimensional echocardiography, anatomical M-mode, pulsed-wave tissue Doppler imaging, and two-dimensional speckle tracking. Correlation between echocardiographic variables and cardiac troponin I was evaluated. Results Early diastolic myocardial velocities decreased significantly in longitudinal (baseline: −17.4 ± 2.4cm/s; end of ride: −15.8 ± 3.2cm/s ( P = .013); morning after: −15.4 ± 3.0cm/s ( P = .0033)) and radial directions (−32.8 ± 3.4cm/s; −28.1 ± 5.8cm/s ( P < .001); −26.4 ± 5.5cm/s ( P < .001)). Early diastolic strain rates decreased significantly in longitudinal (1.58 ± 0.27s−1; 1.45 ± 0.26s−1 ( P = .036); 1.41 ± 0.25s−1 ( P = .013)) and circumferential directions (2.43 ± 0.29s−1; 1.96 ± 0.46s−1 ( P < .001); 2.11 ± 0.32s−1 ( P < .001)). Systolic variables showed ambiguous results. No correlations with serum cardiac troponin I concentrations were evident. Conclusions and Clinical Importance Prolonged exercise in horses is associated with impaired LV diastolic function. Reduced ventricular filling persisted for 7-21 hours despite normalization of biochemical indicators of hydration status, indicating that the observed changes were not entirely related to altered preload conditions. The clinical relevance of cardiac fatigue in horses remains uncertain. [ABSTRACT FROM AUTHOR]

Untrained Thoroughbred horses (6 mares and 6 geldings; 11 yr [SE 1] and 565 kg [SE 11]) were used to evaluate antioxidant gene expression and enzyme activity in blood and skeletal muscle in response to prolonged exercise after receiving 2 levels of dietary selenium for 36 d: 0.1 (CON; n = 6) or 0.3 mg/kg DM (SEL; n = 6). Horses were individually fed 1.6% BW coastal bermudagrass hay, 0.4% BW whole oats, and a mineral/vitamin premix containing no Se. Sodium selenite was added to achieve either 0.1 or 0.3 mg Se/kg DM in the total diet. On d 35, horses underwent 2 h of submaximal exercise in a free-stall exerciser. Blood samples were obtained before (d 0) and after 34 d of Se supplementation and on d 35 to 36 immediately after exercise and at 6 and 24 h after exercise. Biopsies of the middle gluteal muscle were obtained on d 0, before exercise on d 34, and at 6 and 24 h after exercise. Supplementation with Se above the NRC requirement (SEL) increased serum Se (P = 0.011) and muscle thioredoxin reductase (TrxR) activity (P = 0.051) but had no effect on glutathione peroxidase (GPx) activity in plasma, red blood cell (RBC) lysate, or muscle in horses at rest. Serum creatine kinase activity increased (P < 0.0001) in response to prolonged exercise but was not affected by dietary treatment. Serum lipid hydroperoxides were affected by treatment (P = 0.052) and were higher (P = 0.012) in horses receiving CON than SEL immediately following exercise. Muscle expression of TrxR1 was unchanged at 6 h but increased (P = 0.005) 2.8-fold 24 h after exercise, whereas muscle TrxR activity remained unchanged. Glutathione peroxidase activity increased in plasma (P < 0.0001) and decreased in RBC lysate (P = 0.010) after prolonged exercise. A Se treatment ? time interaction was observed for RBC GPx activity (P = 0.048). Muscle GPx1 and GPx3 expression and GPx activity did not change during the 24-h period after exercise. Level of dietary Se had no overall effect on expression of MT1B, MT3, TrxR1, GPx1, GPx3, SOD1, or SOD2 in muscle following exercise. The impact of prolonged exercise on the activities of antioxidant enzymes varied. Furthermore, changes in enzyme activity did not necessarily align with enzyme gene expression following exercise. A higher level of Se intake elevated Se status of untrained horses, increased GPx activity, and lessened lipid peroxidation following exercise, suggesting that Se may be beneficial for mitigating oxidative muscle damage and aiding in postexercise recovery. [ABSTRACT FROM AUTHOR]

This study compared the effect of ridden tölt and trot at 3 speeds on physiological responses in trained adult (15.3 ± 1.6 yr) Icelandic horses. The experiment had a crossover design with 8 horses, 2 treatments (incremental exercise test in tölt and trot), and 2 riders. Each horse performed 2 tests per day (1 gait with 2 riders, minimum 4.5 h between) on 2 separate days, with 1 d of rest in between. The exercise test consisted of three 642-m phases at 3.0 m/s (Speed3), 4.0 m/s (Speed4), and 5.0 m/s (Speed5) and was performed outdoors on a 300- m oval gravel riding track in northern Iceland in May 2012. Heart rate (HR) was measured during warm-up, the exercise test, and after 5, 15, and 30 min of recovery. Blood samples were taken at rest, after warm-up, after each phase of the exercise test, and after 5, 15, and 30 min of recovery. Respiratory rate was counted for at least 15 s at rest, at the end of the exercise test, and at the end of the 30-min recovery, and rectal temperature was measured on these occasions. There were no differences in HR between tölt and trot at any time point (P > 0.05). At Speed3, hematocrit and plasma lactate concentration were greater (P < 0.05) in tölt (40% ± 1%, 1.1 ± 0.06 mmol/L) than in trot (39% ± 1%; 0.9 ± 0.06 mmol/L). There was a prolonged recovery of hematocrit and respiratory rate, a slower decrease in rectal temperature, and a tendency of a prolonged recovery of plasma lactate concentration (P = 0.0675) after tölt. In conclusion, there were only minor differences in physiological responses to tölt and trot in this selected group of experienced adult Icelandic horses and the biological and practical significance of the slightly elevated physiological responses to tölt and the slower recovery remains to be determined. [ABSTRACT FROM AUTHOR]

Exercising equines, especially horses, exhibit significant changes in the physiological responses and several other vital signs. The prominent observable physiological indices are the heart rate (HR), velocity at peak Heart rate (V200), and lactate V[La]. The blood lactate is the biochemical signature of muscular fatigue. Trainings and conditioning schedules have been devised to include the speed at blood lactate levels of 2.0 and 4.0 mM/l. These indices along with recovery of heart rate and blood lactate are important indices for judging the performance of exercising horses. Adaptation to exercise with proper training results in development of cellular tolerance in the exercising muscles and other tissues. With the development of next generation technologies, the analysis of blood and muscle transcriptomes in exercising horses has led to identification of performance genes in race horses. Myostatin (MSTN) genotyping is used to identify and select the horses at early stages for either fast sprint or long distance endurance events. Genes of immune deregulation, mitochondrial respiration, oxidative phosphorylation, tissue repair, tissue remodelling and specific cytokines are among the up regulated genes in the race horses while the most suppressed genes are the ones involved in signal transduction, cell cycle regulation and protein synthesis. Further research is required in the future, to identify the molecular signatures of stress tolerance in horse breeds other than thoroughbreds and race horses, which have evolved and adapted to the climate and utility at specific locations in the world. Such an information would facilitate the horse breeders to devise selection plans in order to improve the exercise and work performance. This would also facilitate diagnosis of the diseases and metabolic disorders that are caused by exercise induced stress. [ABSTRACT FROM AUTHOR]

The use of human equipment in veterinary medicine is very common; therefore, it is essential that it is tested and validated. In this study, a comparison was made between blood levels of glucose, lactate, triglycerides, and cholesterol obtained by the portable device Accutrend® Plus and those found in laboratory methods considered standard for the measurement of parameters of 11 Arabian (and Arabian crossed) horses which completed prolonged endurance effort. Collection was made in five stages: during rest, after 66 km, at the end of the race of 160 km, and 2 and 15 h after the race. Three venous blood samples were collected, the first being used immediately for the measurement of the parameters on the portable device and the other two-with sodium fluoride and without anticoagulant-were packed and immediately sent to a reference laboratory. Statistical analysis consisted of the Student's t test, Pearson correlation, and graphic representation of Bland and Altman () to compare the two measurement methods and Tukey's test for evaluating the effect of variation in relation to the effort according to the standard laboratory method for parameter measurement. Agreement and correlation were not found between the values of glucose, lactate, triglycerides, and blood cholesterol measured by the portable device Accutrend® Plus and the referenced laboratory methods for these parameters in horses undergoing the endurance test, which reinforces the need for more research to definitely validate or invalidate the use of this technology for the species. [ABSTRACT FROM AUTHOR]

Five horses originating from 4 different California race tracks were submitted to the California Animal Health and Food Safety Laboratory for necropsy and diagnostic workup. The 5 horses had a history of sudden collapse and death during exercise. In all of them, massive hemoperitoneum and hemorrhages in other cavities or organs were observed. The liver from these 5 animals and from 27 horses that had been euthanized due to catastrophic leg injuries (controls) were subjected to a rodenticide anticoagulant screen. Traces of brodifacoum, diphacinone, or bromadiolone were detected in the 5 horses with massive bleeding (5/5), and no traces of rodenticides were detected in control horses (0/27). Other frequent causes of massive hemorrhages in horses were ruled out in 4 of the cases; one of the horses had a pelvic fracture. Although only traces of anticoagulants were found in the livers of these horses and the role of these substances in the massive bleeding remains uncertain, it is speculated that exercise-related increases in blood pressure may have reduced the threshold for toxicity of these anticoagulants. [ABSTRACT FROM PUBLISHER]

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This study tested the hypotheses that age-induced alteration in Cortisol, ACTH, and glucose concen-trations are due to differences in the response of the hypo-thalamic-pituitary-adrenal axis and that exercise training would attenuate these differences. Six old (22.0 ± 0.7 yr; mean ± SE) and 6 young (7.3 ± 0.6 yr) unfit Standardbred mares ran 3 graded exercise tests (GXT): before (GXT1), after 8 wk of training (GXT2), and at study end at 15 wk (GXT3). Mares trained 3 dAvk at 60% maximum heart rate. Each mare underwent 5 endocrine stimulation tests pre- and posttraining: 1) control (CON), 2) adrenocortico-tropin hormone (ACTHtest), 3) combined dexamethasone suppression/ACTH (DEX/ACTH), 4) dexamethasone suppression (DEX), and 5) combined DEX/corticotropin releasing factor (DEX/CRF). For CON, there was no dif-ference in plasma Cortisol between age groups pretraining (P = 0.19), but young mares had a 102% higher mean (P = 0.02) plasma Cortisol concentration than old mares posttraining. The pretraining ACTHtest showed young mares had a 72% higher (P = 0.05) overall plasma Cortisol concentration compared to old. There was no overall age difference in Cortisol in the posttraining ACTHtest, but old mares still had lower Cortisol concentrations at 30 min during the test, suggesting decreased adrenal response to ACTH stimulation. There was no difference in Cortisol response between old and young mares in DEX, DEX/ ACTH, or DEX/CRF tests. Young mares had higher (P = 0.02) overall plasma Cortisol concentration posttraining in response to DEX/ACTH, but old mares showed no change. In CON and DEX/CRF, there were no age differ-ences in plasma ACTH concentration, pre- or posttrain-ing. Pretraining, there was no age difference in glucose response to DEX, but posttraining old mares had a 4% (P = 0.04) lower overall plasma glucose concentration compared to young. Posttraining, old mares had lower mean plasma glucose concentrations during DEX com-pared to pretraining (P = 0.02), but there was no change pre- vs. posttraining in young mares (P = 0.19). Old and young mares had lower plasma glucose concentrations posttraining during DEX/ACTH (P < 0.001 and P = 0.05, respectively) and DEX/CRF {P < 0.001 and P = 0.003, respectively) compared to pretraining. Both the pituitary and adrenal glands experience a decline in function with age although the exact mechanisms behind such changes remain unknown. Exercise training facilitates the coun-teraction of these deficits. [ABSTRACT FROM AUTHOR]

It has been observed that microbubbles may pass through the pulmonary circulation of dogs and humans during exercise. In humans, this phenomenon has been associated with lower pulmonary artery pressures, enhanced right ventricular function and greater exercise capacity. In the exercising Thoroughbred horse, extraordinarily high cardiac outputs exert significant pulmonary vascular stresses. The aim of this study was to determine, using contrast echocardiography, whether Thoroughbred horses performing strenuous exercise developed pulmonary transit of agitated contrast microbubbles (PTAC). At rest, agitated contrast was observed in the right ventricle, but not in the left ventricle. However, post-exercise microbubbles were observed in the left ventricle, confirming the occurrence of PTAC with exercise but not at rest. Further investigation is warranted to investigate whether this phenomenon may be associated with superior physiology and performance measures as has been implicated in other species. [ABSTRACT FROM AUTHOR]

Analyses of exhaled breath (EB) and exhaled breath condensate (EBC) are non-invasive modalities for assessing the lower airways but these methods have not been applied to Thoroughbred racehorses in training. The aims of this study were to determine whether EB and EBC could be obtained from Thoroughbred racehorses in the field and to investigate the effects of exercise per se and during different ambient temperatures and humidity on exhaled concentrations of nitric oxide (eNO), carbon monoxide (eCO) and EBC pH. EB and EBC samples were obtained from 28 Thoroughbred racehorses pre- and post-exercise during warm (n = 23) and/or cold (n = 19) ambient temperatures. eNO was detected in 19/84 EB samples. eCO was measured in 39/42 EB samples pre-exercise (median 1.3 ppm) and concentrations decreased significantly post-exercise (median 0.8 ppm, P < 0.005) and were associated with ambient temperature. EBC pH was 4.51 ± 0.23 pre-exercise and increased significantly post-exercise (4.79 ± 0.59, P = 0.003). The study documented the collection of EB and EBC from Thoroughbred racehorses in a field setting. Alterations in concentrations of volatile gases and EBC pH occurred in response to exercise, and were likely to have been influenced by environmental factors. [ABSTRACT FROM AUTHOR]

The main aims of the present review are to provide a bibliometric analysis of the research published on the nutrition of the exercising horse from 1970 to 2010 and to determine whether this research has had any practical impact on feeding practices. In addition, we evaluated whether some of the key nutritional questions posed at the beginning of the 1980s have in fact been answered. Less than 300 publications were published in the period 1970-1980, but a large increase in the number of publications was observed between the period 1981-1990 and the period 1991-2000. Most papers were published in the Equine Veterinary Journal and American researchers, universities or institutes were particularly productive. The majority of the publications were in the areas of fluid balance, fat and glucose metabolism. Using information from field studies, there appears to have been a trend for a reduction in the amount of starch rich concentrates fed to performance horses from 1979 to 2007 and an increase in the use of oil supplementation. Whilst there have been several significant advances in our scientific knowledge of nutritional practices over the past few decades that have become routine practice in the field, others have not cascaded down. Unfortunately, we have not really fully answered any of the questions posed in the early 1980s and whilst it is possible that such questions can never be fully answered, there is also a concern that lack of sufficient funding, especially for the fundamental pieces of information needed to underpin our nutrition advice, will hamper progress in the future. [ABSTRACT FROM AUTHOR]

Water and electrolyte loss from endurance exercise results in physiological disturbances in the horse. The large intestine may serve as a water reservoir and help attenuate dehydration. Dietary constituents may affect the amount of water within the intestine and available for use. This study examined the hydration status of horses fed three common diets for 14 d then subjected to a 60 km exercise test. After an initial training period, horses were assigned to a replicated 3x3 Latin Square. Diets were grass hay (G), 50:50 grass hay:alfalfa hay (GA), and 50:50 grass hay:short-chopped, fibre-based, oil-supplemented mixed feed (GM). Total body water (TBW) tended to be higher (P<0.08) in horses consuming GA and GM than G (65.8±0.8, 65.4±0.8, and 63.9±0.8%, respectively). Body mass (BM) was not different at the start of the exercise test, but when corrected for faecal loss and water intake showed a trend for diet difference during exercise (P<0.08), decreasing more in GM than G (5.1±0.4% vs. 3.4±0.4%; GA 4.2±0.4%). Heart rate was not different except at the end of bout one (after 15 km) when GM was lower than G or GA (P<0.01). Core body temperature, although not different at the start of the exercise test bout, was lower (P<0.05) at the canter in GM. As the GM diet was higher in oil, the increase in oil intake may have been responsible for the differences observed. However, more likely, the higher TBW with the GM and GA diets at the initiation of exercise, associated with more readily fermentable fibre components, may have provided a greater 'pool' of available water for increased thermoregulation via sweating, allowing maintenance of a lower core body temperature during exercise at the expense of increased BM loss. [ABSTRACT FROM AUTHOR]

This study assessed the insulin response to forage intake with varying crude protein (CP) content in horses at rest and after exercise. Six geldings were fed three grass haylage-only diets for 7 days according to a 3x3 Latin square design. On day 7, blood samples were collected before and for 120 min after feeding 15% of the daily allowance before exercise (feeding A) and after standardised exercise (feeding B). Feed samples were collected before each feeding. Dry matter (DM) and nutrient content varied (DM: 37-58%, water-soluble carbohydrates minus fructans (WSC-f): 3-12% of DM, CP: 10-15% of DM) which resulted in a variation in nutrient intake within haylage batches. Based on individual CP and WSC-f intakes, intake groups were therefore formed (low and high CP intake; ≤ and >180 g CP/100 kg body weight, respectively and low and high WSC-f intake; ≤ and >100 g/100 kg body weight, respectively). Amino acids were analysed and intakes were generally higher in the high CP group than in the low CP group. An ANOVA model including horse, CP group and WSC-f intake explained 95% of the variation in plasma insulin response compared to 87% using a model including horse and WSC-f group alone. The plasma insulin area under curve (AUC) following feeding A tended to be higher in the high CP group than in the low CP group (P=0.08), but there was no difference after feeding B. Plasma glucose AUC was not affected by CP group (P>0.05). The study indicates that the post-prandial plasma insulin response in horses fed a forage-only diet is increased by high WSC-f intake but may also be increased by high CP intake, at least at rest. However, due to the low number of observations further studies are needed. [ABSTRACT FROM AUTHOR]

Background: Soundness of an individual horse is important for animal welfare and owner economy. However, knowledge of health status in normal horse populations is limited due to lack of systematic health recordings. The aim of the investigation was to study the prevalence of veterinary clinical findings in 4-5-year-old Swedish warmblood riding horses, and their influence on overall health scores, where associations to future longevity has been indicated. Results: The prevalence of clinical findings in 8,281 horses examined during 1983-2005 was studied according to a standardised protocol and related to overall health scores in linear statistical models. Effects of sex, age, examination event and changes over time were included. In total, 49% of the horses had clinical findings of medical health (MED), 42% in hooves (HOOF) and 74% of palpatory orthopaedic health (PALP). However, only 6%, 3% and 24% had moderate or severe findings, of MED, HOOF and PALP, respectively. Flexion test reactions were reported in 21% of the horses (5% moderate/severe), heavily influencing the overall score (H2). One fifth of these horses also had findings of unprovoked lameness while 83% had PALP findings (44% with moderate/severe findings). Acute clinical signs, i.e. heat or soreness, had a large influence on the H2 score but were rare, whereas more common clinical findings had smaller effects on overall health. Large variations in recorded health results were observed among events. A decrease in findings has occurred since 1983, in particular for PALP findings. Conclusions: Results of occurrence and relevance of evaluated clinical findings could be used for advice on preventive actions to keep horses sound, and possibly for benchmarking, and genetic evaluation of health traits. The distinct effect of event on recorded clinical findings emphasises that further harmonisation of veterinary examinations are desirable. [ABSTRACT FROM AUTHOR]

Objective--To evaluate the effects of a single incremental exercise test (IET) on mRNA expression and protein content of monocarboxylate transporter (MCT) 1 and MCT4 in the gluteus medius muscle of Thoroughbreds. Animals--12 Thoroughbreds (6 males and 6 females; age, 3 to 4 years). Procedures--Horses underwent an lET before and after 18 weeks of high-intensity exercise training (HIT). Horses were exercised at 90% of maximal oxygen consumption for 3 minutes during the initial 10 weeks of HIT and 110% of maximal oxygen consumption for 3 minutes during the last 8 weeks of HIT Gluteus medius muscle biopsy specimens were obtained from horses before (baseline), immediately after, and at 3, 6, and 24 hours after the IET Results--Expression of MCT1 and MCT4 mRNA was upregulated at 3 and 6 hours after the IET in muscle specimens obtained from horses prior to HIT (untrained horses) and at 6 hours after the IET in muscle specimens obtained from horses after HIT (trained horses). For both untrained and trained horses, MCT1 and MCT4 protein contents were increased at 6 hours after the IET and did not differ at 24 hours after the IET, compared with those at baseline. Conclusions and Clinical Relevance--Results indicated that a single IET resulted in transient increases in MCT1 and MCT4 mRNA expression and protein content in untrained and trained horses. These results may be important for the elucidation of exercise-induced alterations in lactate metabolism [ABSTRACT FROM AUTHOR]

Objective--To investigate histomorphometric changes in the cartilage and subchondral bone of the third carpal bone associated with conditioning exercise in young Thoroughbreds. Animals--Nine 18-month-old Thoroughbreds. Procedures--Both third carpal bones of 9 horses (4 exercised spontaneously at pasture only and 5 given additional conditioning exercise beginning at a mean age of 3 weeks) were evaluated. Histomorphometric variables (hyaline and calcified cartilage thickness and collagen orientation; vascular channel area, number, and orientation; and osteochondral junction rugosity) of the third carpal bone, sampled at 4 dorsopalmar sites in the radial facet, were compared between the exercised and nonexercised groups. Results--The vascular channel area measured at the 4 dorsopalmar sites was larger in the exercised group than in the control group, but none of the variables were significantly different between groups. Both groups had significant site-specific variations in all measured variables. Most importantly, the vascular channel area was highest in the most dorsal aspect. Conclusions and Clinical Relevance--Results suggested that the mild exercise imposed in both groups during the developmental period appeared to be associated with an increase in the vascular channel area beneath the calcified cartilage layer in the third carpal bone. This increased vascular channel area could also be associated with high stress in the dorsal aspect of the radial facet, a region that is known to be vulnerable to osteochondral fragmentation. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate workload using suitable parameters related to the physical effort exerted by horses involved in eventing competitions in order to describe the workload intensity and energy demands placed upon such horses. Heart rate (HR), running speed (S), distance covered (Dist), performance duration (D) and blood lactate (Lact) concentrations were measured in horses competing at either the intermediate level (IL) or advanced level (AL) in order to identify workload differences between experience classes. Ten warmblood horses were monitored during an official two-day eventing competition; mean HR (HRmean, bpm), maximum HR (HRmax, bpm), mean S (Smean, m/min), max S (Smax, m/min), D (min) and Dist (m) were assessed during the warm-up and competition phases of each eventing test (dressage, show jumping, cross country). To calculate heart rate recovery (HRR), HR data were collected within the first 3 minutes following the completion of each of the 3 competition phases. Energy expenditure (EE) was estimated using the HR/VO2 relationship. Differences between the groups (AL vs. IL) in HRmean, HRmax, %HRmean, %HRpeak (HR expressed as a percentage of the maximum HR peak obtained during a fast gallop training session), S, D, and Dist were assessed using one-tailed unpaired t-tests for both warmup and competition phases; also differences for EE were evaluated. The relationship between HR and S was also determined for warm-up and competition phases using one-tailed Person's correlations. The relationship between HR decrease during the first 3 min following competition phase completion and recovery time was investigated by multiple nonlinear curve estimation procedures. The results reveal the cross country test to be the most demanding of the eventing competition, requiring significantly greater levels of muscular and energetic effort, in terms of Lact production and EE, with higher values recorded in the AL horses compared to IL horses. The data also show that riders need to optimise warm-up duration and quality in accordance with their competition category. The calculation of HRR is also shown to be an appropriate approach for gauging workload after high-intensity exercise, but not after low-intensity exercise since HRR may be influenced by external factors, like how excited a horse is. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to assess the effect of the Chilean rodeo exercise on some blood constituents, classically used to assess welfare, during rest; training with and without steer; and before and after official competitions. During the training season, 13 horses were assessed at their farms of origins, and samples were taken at rest and after training with and without a steer; then during the competition season, 16 horses were assessed at four different times, one before and three after the competition. The blood constituents assessed were packed cell volume (PCV), total proteins, fibrinogen, cortisol, neutrophil:lymphocyte ratio, creatine phosphokinase, aspartate transaminase, glutathione peroxidase, and serum amyloid A. Analysis of variance for repeated measures was applied using the Statistix 8.0 software, and a significance level of P < .05 was applied. For horses assessed during exercise with and without a steer, significant differences were observed for PCV, which were significantly lower at rest than after both exercises, and total proteins, which showed a significant increase only after exercise with steer. In the case of official competitions, PCV was significantly higher immediately after rodeo, and the lowest value for cortisol was observed the evening after competition (P < .05); among the enzymes assessed, creatine phosphokinase plasma concentrations immediately after rodeo and the evening after competition were significantly higher than concentrations the next morning. The use of physiological indicators did not seem to be sufficient to assess the overall effect of rodeo on the welfare of these horses, and other types of indicators should be considered in future studies. [Copyright &y& Elsevier]

The article presents a study which examined the reference zinc values in racehorses, the effects of exercise and sweating on the clinical application of zinc testing, and the relationship between serum zinc levels and diseases in racehorses. Particular focus is given to the materials and methods used on Thoroughbred racehorses. It also discusses results which suggested that measurement of serum zinc levels is a potential marker for monitoring inflammatory state of Thoroughbred racehorses.

The aim of this study was to evaluate the daily rhythms of peroxidative parameters in untrained and trained horses. Blood samples were collected every 4 h for a 48-h period for the determination of reactive oxygen metabolites test (d-ROMs), antioxidant barrier (Oxy-ads), thiol antioxidant barrier (SHp) and lipid peroxidation (LPO). Two-way anova showed a significant effect of time of day on all parameters studied, except on LPO. Higher values of Oxy-ads and SHp were observed in trained horses during both days of monitoring (p < 0.01). All studied parameters, except for LPO, showed robust daily rhythms. Their acrophases occurred during the day in untrained horses and in the evening in trained horses. Our results showed that training increases antioxidative capacity and demonstrated that the daily rhythms of antioxidative parameters can be modified by training. [ABSTRACT FROM AUTHOR]

Objective--To determine the effects of yearling sale purchase price, exercise history, lameness, and athletic performance (speed) on purchase price of 2-year-old in-training Thoroughbreds and to compare the distance exercised within 60 days prior to 2-year-old in-training sales between horses with high yearling sale purchase prices versus those with low yearling sale purchase prices and between horses with lameness during training and those without lameness during training. Design--Prospective study. Animals--51 Thoroughbreds. Procedures--Thoroughbreds purchased at a yearling sale were trained prior to resale at 2-year-old in-training sales. Amount of exercise and lameness status during training and speed of horses at 2-year-old in-training sales were determined. Data were analyzed via the Wilcoxon rank sum test and ANOVA. Results--Median purchase price of horses at 2-year-old in-training sales was $37,000. The 2-year-old in-training sale purchase price was associated with yearling sale purchase price and distance galloped within 60 days prior to and speed recorded at 2-year-old in-training sales. Conclusions and Clinical Relevance--Horses with high yearling sale purchase prices typically had high 2-year-old in-training sale purchase prices, had low distances galloped within 60 days prior to 2-year-old in-training sales, and were classified as fast at 2-year-old in-training sales. Lameness alone was not associated with 2-year-old in-training sales purchase price. However, lameness was associated with a low distance galloped before 2-year-old in-training sales, particularly for horses with a high yearling sale purchase price; this finding suggested that yearling sale purchase price can affect training management decisions for horses with lameness. [ABSTRACT FROM AUTHOR]

Abstract: Across all equestrian disciplines, the single largest reason for wastage is musculoskeletal injury. It is, therefore, of importance that management and competition structures are in place to optimize the development of the equine musculoskeletal system to minimize wastage. Data from other species and, in particular, humans have demonstrated the benefit of early exercise and the dire consequences of inactivity. The horse has evolved as a cursorial animal capable of covering up to 10 km/d within 9 days of birth. Yet, modern equine management systems restrict, rather than promote, early exercise. Foals were shown to have a positive response to early preweaning paddock exercise (greater cartilage health), and more recent work has demonstrated that exercise over and above that normally occurring with pasture-reared foals, introduced as early as 3 weeks old, had positive effects on the equine musculoskeletal system. The response of juvenile horses to additional exercise is because of the tissue being responsive to priming. Epidemiological data indicate that the window for tissue modification may still be open when the horse is a yearling and even as a 2 year old. However, the method in which the exercise is applied may be of as much importance as the timing of the stimuli. A recent prospective study of both Thoroughbred and Standardbred horses demonstrated that the horses that entered training as 2 year olds had longer and more successful racing careers than those that entered training later in life. It would appear that even the initial stages of training are enough to provide a positive stimulus, as horses first registered with a trainer at 2 years old had the same advantages as those that raced as 2 year olds. The physiological, clinical, and epidemiological data indicate that, rather than restrict exercise and the use of horses at a young age, we should realign expectations with the capability of the horses’ musculoskeletal system and evolutionary template to maximize orthopedic health. [Copyright &y& Elsevier]

Objective--To identify differences in intersegmental bending angles in the cervical, thoracic, and lumbar portions of the vertebral column between the end positions during performance of 3 dynamic mobilization exercises in cervical lateral bending in horses. Animals--8 nonlame horses. Procedures--Skin-fixed markers on the head, cervical transverse processes (C1-C6) and spinous processes (T6,T8,T10,T16, L2, L6, S2, and S4) were tracked with a motion analysis system with the horses standing in a neutral position and in 3 lateral bending positions to the left and right sides during chin-to-girth, chin-to-hip, and chin-to-tarsus mobilization exercises. Intersegmental angles for the end positions in the various exercises performed to the left and right sides were compared. Results--The largest changes in intersegmental angles were at C6, especially for the chin-to-hip and chin-to-tarsus mobilization exercises. These exercises were also associated with greater lateral bending fromT6 to S2, compared with the chin-to-girth mobilization or neutral standing position. The angle at C1 revealed considerable bending in the chin-to-girth position but not in the 2 more caudal positions. Conclusions and Clinical Relevance--The amount of bending in different parts of the cervical vertebral column differed among the dynamic mobilization exercises. As the horse's chin moved further caudally, bending in the caudal cervical and thoracolumbar regions increased, suggesting that the more caudal positions may be particularly effective for activating and strengthening the core musculature that is used to bend and stabilize the horse's back. [ABSTRACT FROM AUTHOR]

Objective--To determine the effects of clenbuterol, at a dosage of up to 3.2 µg/kg for 14 days, PO, on skeletal and cardiac muscle in healthy horses undergoing treadmill exercise. Animals--12 healthy horses from 3 to 10 years old. Procedures--Horses were randomly assigned to a control group (n = 6) or clenbuterol group (6) and received either saline (0.9% NaCl) solution or clenbuterol, PO, every 12 hours for 14 days. Horses were subjected to submaximal treadmill exercise daily during treatment. Muscle biopsy specimens were collected before and after treatment for determination of apoptosis. Echocardiographic measurements, serum clenbuterol and cardiac troponin I concentrations, and serum activities of creatine kinase and aspartate aminotransferase were measured before, during, and after treatment. Jugular venous blood samples were collected every 3 days during treatment. Echocardiography was repeated every 7 days after beginning treatment. Response variables were compared between treatment groups and across time periods. Results--No significant effect of clenbuterol or exercise on response variables was found between treatment and control groups at any time point or within groups over time. Conclusions and Clinical Relevance--Results did not reveal any adverse effects of treatment with an approved dose of clenbuterol on equine cardiac or skeletal muscle in the small number of horses tested. [ABSTRACT FROM AUTHOR]

This article presents several abstracts related to horse research for papers that were presented at the XXII Reunión ALPA conference in Montevideo, Uruguay, from October 24-26, 2011, including nutrition, genetics, and exercise research.

Bilateral vocal fold paralysis (BVCP) is a life threatening condition and appears to be a good candidate for therapy using functional electrical stimulation (FES). Developing a working FES system has been technically difficult due to the inaccessible location and small size of the sole arytenoid abductor, the posterior cricoarytenoid (PCA) muscle. A naturally-occurring disease in horses shares many functional and etiological features with BVCP. In this study, the feasibility of FES for equine vocal fold paralysis was explored by testing arytenoid abduction evoked by electrical stimulation of the PCA muscle. Rheobase and chronaxie were determined for innervated PCA muscle. We then tested the hypothesis that direct muscle stimulation can maintain airway patency during strenuous exercise in horses with induced transient conduction block of the laryngeal motor nerve. Six adult horses were instrumented with a single bipolar intra-muscular electrode in the left PCA muscle. Rheobase and chronaxie were within the normal range for innervated muscle at 0.5560.38 v and 0.3860.19 ms respectively. Intramuscular stimulation of the PCA muscle significantly improved arytenoid abduction at all levels of exercise intensity and there was no significant difference between the level of abduction achieved with stimulation and control values under moderate loads. The equine larynx may provide a useful model for the study of bilateral fold paralysis. [ABSTRACT FROM AUTHOR]