Endurance Horses Research Articles

Return to sport activity following ultrasonographic diagnosis and conservative management of spontaneous injuries of the serratus cervicis ventralis and serratus thoracis ventralis muscles in 11 endurance horses.

To describe the clinical diagnosis, ultrasound findings, and outcome of 11 endurance horses with injuries to the serratus ventralis thoracis (SVT) or serratus ventralis cervicis (SVC) muscle. 11 endurance horses competing in medium- to high-level competitions and presenting with lameness caused by injuries to the SVT or SVC muscle, as confirmed by ultrasonography. Physical examinations revealed swelling caudal to the shoulder region associated with dorsocranial displacement of the scapula and edema of the ventral thorax for horses with SVT injuries. Swelling cranial to the scapula and edema of the pectoral area were identified among horses with injuries to the SVC. Dynamic examinations revealed moderate-to-severe reduction of the cranial phase of the stride at the walk; at the trot, a lameness score of 2 to 3/5 was assigned (modified American Association of Equine Practitioners Lameness Scale). Ultrasonography revealed moderate-to-severe increases in size of the muscle body, heterogeneous echogenicity, loss of the striated muscle pattern, and varying degrees of perimuscular edema. All horses were able to resume full training and competition in an average of 216 days (range, 74 to 362 days) and 148 days (range, 112 to 309 days) for injuries of the SVT and SVC, respectively. This case series is the first to describe the clinical and ultrasonographic features of spontaneous injuries to the SVT or SVC. Ultrasonography for diagnosis was simple and well tolerated by the horses.

Workload and spirometry associated with untethered swimming in horses

BackgroundSwimming has been used empirically for rehabilitation and conditioning of horses. However, due to challenges imposed by recording physiological parameters in water, the intensity of free swimming effort is unknown.ObjectivesMeasure the physiological workload associated with untethered swimming in horses.Five fit Arabian endurance horses were assessed while swimming in a 100 m-long indoor pool. Horses were equipped with a modified ergospirometry facemask to measure oxygen consumption (V̇O2) and ventilatory parameters (inspired/expired volumes, VI, VE; peak inspiratory/expiratory flows, PkVI, PkVE; respiratory frequency, Rf; minute ventilation, VE; inspiratory/expiratory durations and ratios, tI, tE, tI/ttot, tE/ttot); and an underwater electrocardiogram that recorded heart rate (HR). Postexercise venous blood lactate and ammonia concentrations were measured. Data are reported as median (interquartile ranges).ResultsHorses showed bradypnea (12 breaths/min (10–16)) for the first 30 s of swimming. V̇O2 during swimming was 43.2 ml/(kg.min) (36.0–56.6). Ventilatory parameters were: VI = 16.7 L (15.3–21.8), VE = 14.7 L (12.4–18.9), PkVI = 47.8 L/s (45.8–56.5), PkVE = 55.8 L/s (38.3–72.5), Rf = 31.4 breaths/min (20.0–33.8), VE = 522.9 L/min (414.7–580.0), tI = 0.5 s (0.5–0.6), tE = 1.2 s (1.1–1.6), tI/ttot = 0.3 (0.2–0.4), tE/ttot = 0.7 (0.6–0.8). Expiratory flow tracings showed marked oscillations that coincided with a vibrating expiratory sound. HR was 178.0 bpm (148.5–182.0), lactate = 1.5 mmol/L (1.0–1.9) and ammonia = 41.0 µmol/L (36.5–43.5).ConclusionsFree (untethered) swimming represents a submaximal, primarily aerobic exercise in horses. The breathing pattern during swimming is unique, with a relatively longer apneic period at the beginning of the exercise and an inspiratory time less than half that of expiration.

Lesion Distribution in the Metacarpophalangeal and Metatarsophalangeal Region of 341 Horses Using Standing Magnetic Resonance Imaging.

Pain localised to the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) region represents a frequent cause of lameness in sport horses, and standing magnetic resonance imaging (MRI) of these regions is increasingly being acquired. This multicentre retrospective study describes the ranges of abnormalities identified on standing MRI of the MCP/MTP region and compares patterns of abnormalities between forelimbs, hindlimbs and different sports disciplines. In total, 341 MRI reports were reviewed. Subchondral bone plate irregularities, condylar and proximal phalanx pathologies were frequently identified with subchondral bone defect, sclerosis and increased intensity on STIR images often described. Medial pathology was frequently identified in the forelimbs, and more lateral pathology was reported in the hindlimbs, which could potentially reflect differences in the loading patterns. Significant differences in MRI findings were found between different sports activities, with MCP/MTP bone pathology occurring more frequently in MRI reports from race and endurance horses and MCP/MTP soft tissue injuries being reported more frequently in dressage and show-jumping horses, particularly in the suspensory apparatus, including the distal sesamoidean ligaments. The findings of this study identify patterns of MCP/MTP abnormalities detected using standing MRI, with differences seen between forelimbs and hindlimbs and between different sports disciplines.

Physiological stress responses in horses participating in novice endurance rides

Horses participating in endurance events encounter enormous physical challenges. Heart rate (HR) and heart rate variability (HRV) have been reported before and after endurance rides, but these have not been determined during the rides. Moreover, the modulation in HRV and haematology in horses with different ride results (completed a course or disqualified due to irregular gait) have not been elucidated. Therefore, this study aimed to investigate changes in HR, HRV, and haematological parameters during novice endurance rides and to compare these parameters between horses that successfully completed the course (SC) or were disqualified for irregular gait (FTQ-GA). Beat-to-beat (RR) intervals of 16 healthy horses (aged 6–14 years) were recorded before and throughout the approximately 40 km endurance event. Blood samples were taken at the pre-ride inspection and after passing each veterinary inspection. HRV and haematology measures were determined from nine SC and seven FTQ-GA horses. Horses with different ride results demonstrated distinctive physiological stress responses. Increases in PCV, RBC, WBC and neutrophils after completing the ride were found only in SC horses, implying that they were ridden with greater effort than FTQ-GA horses. A reduction in HRV during warm-up, followed by a significant reduction during the first and second riding phases, was observed. HRV returned to baseline at the compulsory rest period of both phases. FTQ-GA horses experienced lower RR intervals, RR triangular index, modified deceleration capacity, very-low-frequency band, and parasympathetic nervous system index, coinciding with higher HR and sympathetic nervous system and stress indices than SC horses. These results indicated that endurance horses revealed a shift toward sympathetic activity during the ride. Lower parasympathetic activity in FTQ-GA horses suggests they were under more stress or discomfort than SC horses in novice endurance rides. These results have welfare implications, indicating the need for additional rest breaks in FTQ-GA horses.

Retrospective study of standardised field exercise test on injury development, blood lactate and recovery time in endurance horses

Abstract This study investigated the effect of environment, horse and type of different field standardised exercise tests (fSET) on incremental lactate concentration and recovery time in endurance horses. Forty-eight endurance horses underwent one or multiple fSET on a 700-m all-weather racetrack. The fSET comprised phase 1 canter at 19.5-21.5 km/h for 19 km (group N), or 37 km split by 20 minutes of rest (group E1) or 37 km (group E2), followed by phase 2 canter at 26-32.6 km/h and phase 3 at 27.7-42.8 km/h, for 1,400 m each for all groups. Blood lactates were recorded after each phase. Linear mixed models were built with blood lactate value and recovery time as dependent variables and horse and environment data, and type of fSET as fixed effect variables, with horse and horse × fSET group as random effects. Data from a total of 130 fSETs were considered; lactate values were 0.78-7.73 mmol/l (median 1.79 mmol/l) for phase 1, 1.70-10.68 mmol/l (median 3.89 mmol/l) for phase 2, and 3.7-20.86 mmol/l (median 8.74 mmol/l) for phase 3. Blood lactate values after phase 1 and phase 2 were significantly lower in group E1 (median 1.49 mmol/l; median 3.12 mmol/l) compared with group N (median 2.77 mmol/l; median 5.28 mmol/l; ) and group E2 (median 2.06 mmol/l; median 4.39 mmol/l; ). Blood lactate after phase 3 did not differ between groups. There were two medical and 19 minor musculoskeletal issues within 2 hours after the fSETs. Weather temperature affected blood lactate values after phase 1 and 2 (R = 0.62-0.63). Blood lactate after phase 1 (R = 0.93) and 2 (R = 0.66) affected values after phase 2 and 3, respectively. There was a considerable variation among horses and horse × fSET group random effects. Moreover, blood lactate values are affected by both weather conditions and by horse individual characteristics.

Avaliação de componentes do metabolismo lipídico basal e adiposidade de cavalos Árabes treinados para corrida e para Enduro

ABSTRACT: Endurance and flat race are entirely different efforts and thus require completely different organism adaptations to achieve the performance. This study aimed to examine the difference in basal lipid metabolism in Arabian horses undergoing different training regimens for endurance and race and possible gender differences. The study enrolled sixty male and female’ Arabian horses; thirty were trained for race, and thirty were trained for 80 km endurance races. The analyses included body condition score, body weight, body mass index, % body fat, and blood collected to determine triglycerides, total cholesterol, low-density proteins, high-density proteins, and non-esterified fatty acids. Ultrasonography was used to measure the thickness of the subcutaneous fat layer in the longissimus dorsi muscle, as well as the thickness of the rump fat and the cross-section of the gluteus medius muscle. This study showed that lipid profile is more influenced by type of exercise than by gender, being more efficient on endurance horses.

Increased radiopharmaceutical uptake in skeletal muscle in 26 flat racing and endurance horses (2017–2021)

SummaryBackgroundIncreased radiopharmaceutical uptake (IRU) in skeletal muscle in horses has been previously reported but only a few authors describe its location in detail.ObjectivesTo describe and document the distribution of IRU in skeletal muscle in a population of flat racing and endurance horses.Study designRetrospective descriptive study.MethodsBone phase nuclear skeletal scintigraphy studies of 17 endurance and 9 racehorses with IRU in skeletal muscle were reviewed. The affected muscles were described and differences between endurance and flat racing horses were analysed. Ultrasonographic appearance of the muscles with IRU was also described when available.ResultsA total of 22 hindlimb scans (14 endurance horses, 8 racehorses) and 7 forelimbs scans (5 endurance horses, 2 racehorses) were analysed. In the hindlimbs, IRU was most frequently observed in the semitendinosus muscle in endurance horses (7/14, 50%) and in the gluteus medius muscle in racehorses (4/8, 50%). Bilateral IRU in the same muscle was often observed (11/22, 50%) in the hindlimbs. In 87.5% of the studies with IRU in the biceps femoris (7/8) or the semitendinosus muscles (7/8), the IRU was bilateral. In the forelimbs, IRU was most frequently observed in the triceps brachii (2/5, 40%) and latissimus dorsi (2/5, 40%) muscles in endurance horses and in the brachiocephalicus muscle in racehorses (2/2, 100%). The distribution of the skeletal muscles with IRU was more varied in endurance than in flat racehorses. No statistically significant difference was found in the distribution of the skeletal muscles with IRU between endurance and racehorses.ConclusionsEven though no statistical differences between groups could be demonstrated, this study describes the frequent location of IRU in muscle in the semitendinosus of endurance horses and in the gluteus medius of flat racehorses included in this study. The distribution of muscles with IRU was more variable in endurance horses.

Metabolic effects of training endurance horses in a field setting

Abstract Changes in serum biochemistry and skeletal muscle of horses in response to individual endurance rides of varying distance have been reported, as have the effects of submaximal treadmill training. This study evaluated the effects of a controlled field endurance training programme on energy metabolism. Five Arabian horses 6.8 ± 2.0 years (mean ± standard deviation) were trained for 16 weeks over progressively longer distances. The biceps femoris, triceps long head, and semitendinosus muscles were biopsied before and after 4-weekly runs of 10, 20 and 30 miles, respectively, and before and after 10, 20, 30 and 50 miles of a fourth run at the end of the training programme to measure 3-hydroxyacyl-CoA-dehydrogenase (HAD) and succinate dehydrogenase (SDH) activities and triglyceride (TG) and glycogen concentrations in those biopsies. Blood samples were obtained simultaneously to measure serum TG, free fatty acid (FFA), glycerol, glucagon, insulin, and cortisol concentrations. Data were analysed using RM-ANOVA for effects of training and distance. was considered significant. Training increased resting glycogen and TG concentrations in the biceps (, ), triceps (, ) and semitendinosus (, ), respectively. Both HAD and SDH activities increased in the biceps femoris (; ) and triceps (; ), respectively, but not in the semitendinosus. There was no training effect detected on serum hormone responses to exercise distance although serum glycerol (), glucagon () and cortisol () concentrations increased with increasing run distance, while insulin concentration decreased (). Glucagon and cortisol concentrations were correlated (r = 0.67; ). Serum TG decreased with exercise but at a slower rate following training, and serum FFA were higher during exercise following training when compared to the partially trained state. Overall, endurance training enhanced peripheral mobilisation of fat and its utilisation by working muscle, and resting muscle glycogen stores increased.

Effects of exercise and training on plasma and blood volumes in Thoroughbreds and endurance horses

Abstract Exercise-and training-induced changes in plasma (PV) and blood volumes (BV) have been well documented in racehorses but not in endurance horses. We aimed to determine and compare the effects of training and exercise on BV and PV in Thoroughbred racehorses and endurance horses. Six endurance horses underwent a 4-month training program under saddle and 11 Thoroughbreds completed a racehorse-appropriate interval training program for 3-4 months on a racetrack. PV and BV were measured before and after training at rest and post-exercise using the indocyanine green dilution technique. For the Thoroughbreds, exercise consisted of a 1000 m breeze on a racetrack. The endurance horses completed rides of 10, 20 and 30 miles during training and 50 miles when fully trained. Data were analysed using the Wilcoxon signed rank test, Mann-Whitney test and paired t test, with significance set at . Although absolute PV and BV were greater in Thoroughbreds, mass-specific PV and BV were mostly greater in endurance horses. Untrained endurance horses had a greater mass-specific PV and BV at rest (PV: 65 ± 4.1 vs 54 ± 5.7 ml/kg, ; BV: 101 ± 8.0 vs 83 ± 8.8 ml/kg; ) and a greater PV (60 ± 3.8 vs 44 ± 4.8 ml/kg; ) but not BV (108 ± 2.0 vs 112 ± 14.3 ml/kg) after exercise. Training induced an increase in resting PV and BV to 73 ± 4.3 and 116 ± 14.1 ml/kg, respectively, in endurance horses (), and an increase in PV and BV after 30 miles endurance exercise (PV: 60 ± 3.8 vs 80 ± 15.8 ml/kg; ; BV: 108 ± 2.0 vs 139 ± 26.5 ml/kg; ). Resting and post-exercise PV and BV increased following training in the Thoroughbreds: resting PV = 57 ± 5.1 ml/kg (), resting BV = 89 ± 8.3 ml/kg (); post-exercise PV = 49 ± 4.8 ml/kg (), post-exercise BV = 112 ± 14.3 ml/kg (untrained) vs 124 ± 18.2 ml/kg (trained), ). PV increased in response to exercise in endurance horses but decreased in Thoroughbreds. Endurance horses had smaller absolute PV and BV but greater mass-specific resting PV and BV than Thoroughbreds.

Assessment of the Effect of Thyme Essential Oil on Biochemical Parameters in Endurance Horses

Assessment of the Effect of Thyme Essential Oil on Biochemical Parameters in Endurance Horses

The Relevance of the Expected Value of the Proportion of Arabian Genes in Genetic Evaluations for Eventing Competitions.

The Arabian horse is a generally reliable sport horse, and continues to be a remarkable endurance horse, so the relevance of the expected value of the proportion of Arabian genes (EV%AG) in horses participating in eventing could be a relevant factor. A total of 1089 horses participating in eventing (8866 records) were used. A GLM revealed that the EV%AG was significant in dressage, show jumping and cross-country. A BLUP genetic evaluation was computed with five genetic models (without the EV%AG (0) using as a covariate (A), as a fixed effect (B), with variance heterogeneity, and in genetic groups without (C) and with (D)). Dressage heritability ranged from 0.103 to 0.210, show jumping ranged from 0.117 to 0.203 and cross-country ranged from 0.070 to 0.099. The lowest DIC value was used as a criterion of fitness. The best fits (those which included variance heterogeneity) showed fewer than two points of difference in DIC values. The highest average estimated breeding value in dressage, show jumping and cross-country was found for horses with an expected value of the proportion of Arabian genes of 0%, ≥1% to <25%, and 100%, respectively. Therefore, the best way to model the EV%AG effect seems to be by considering the variance heterogeneity.

Pre-Ride Biomarkers and Endurance Horse Welfare: Analyzing the Impact of the Elimination of Superoxide Dismutase, δ-Aminolevulinic-Dehydratase, Thiobarbituric Acid Reactive Substances, Iron, and Serum Amyloid A Levels in Elite 160 km Endurance Rides.

High elimination rates and concerns for horse welfare are important issues in endurance riding. Improved understanding of the causes of elimination could increase completion rates in this sport. We have identified pre-ride laboratory risk factors that enable an assessment of potential elimination before the ride. A longitudinal cohort study was performed among 49 healthy horses competing in the 160 km endurance ride at the 2016 World Championship of Endurance Riding in Samorin/Slovakia. Blood samples were taken before the event. For statistical evaluation, horses were categorized into three groups: finishers, lame horses, and metabolically eliminated horses. Risk factors were calculated for each group using multinominal logistic regression. δ-Aminolevulinic-dehydratase (ALAD), thiobarbituric acid reactive substances (TBARSs), iron, and serum amyloid A (SAA) were measured and did not show an impact on the race outcome, but elevated pre-ride superoxide dismutase (SOD) was shown to have an effect on lameness elimination (p = 0.011). It might serve as an indicator for withdrawing horses at risk of later elimination before endurance rides, ultimately resulting in lower elimination rates and an increase in overall horse welfare.

Effects of calcium supplementation to resuscitation fluids in endurance horses: A randomized, blinded, clinical trial.

The addition of calcium to resuscitation fluids is a common practice in horses, but studies evaluating the effects of calcium supplementation are limited. In healthy horses, decreases in heart rate and changes in serum electrolyte concentrations have been reported. Calcium gluconate administration at a rate of 0.4 mg/kg/min to eliminated endurance horses with metabolic problems will affect heart rate, gastrointestinal sounds, and serum electrolyte concentrations. Endurance horses eliminated from the Tevis Cup 100-mile (160 km) endurance ride for metabolic problems and requiring IV fluid therapy were eligible. Sixteen horses were randomly assigned to receive 0.4 mg/kg/min of calcium (23% calcium gluconate solution) over 1 hour diluted in 10 L of a non-calcium containing isotonic crystalloid (CAL group) or 10 L of a non-calcium containing isotonic crystalloid (CON group). Staff members administering the fluids were blinded to treatment group. Blood samples were collected and physical examinations performed before and after treatment. Heart rates were recorded every 15 min during fluid administration. Data were compared using 2-way analysis of variance (ANOVA) with repeated measures for continuous variables and Fisher's exact test for categorical variables. Calcium was associated with lower heart rates 45 min after starting the infusion (P = .002). Gastrointestinal sounds were less likely to improve in the calcium group compared with the control group (P = .005). An increase in plasma phosphorus concentration (P = .03) was associated with calcium administration. Intravenous calcium supplementation to endurance horses eliminated from competition after development of metabolic problems may decrease heart rate but impairs improvement in gastrointestinal sounds.

Characterization of exercise-induced hemolysis in endurance horses.

Exercise-induced hemolysis occurs as the result of intense physical exercise and is caused by metabolic and mechanical factors including repeated muscle contractions leading to capillary vessels compression, vasoconstriction of internal organs and foot strike among others. We hypothesized that exercise-induced hemolysis occurred in endurance racehorses and its severity was associated with the intensity of exercise. To provide further insight into the hemolysis of endurance horses, the aim of the study was to deployed a strategy for small molecules (metabolites) profiling, beyond standard molecular methods. The study included 47 Arabian endurance horses competing for either 80, 100, or 120 km distances. Blood plasma was collected before and after the competition and analyzed macroscopically, by ELISA and non-targeted metabolomics with liquid chromatography-mass spectrometry. A significant increase in all hemolysis parameters was observed after the race, and an association was found between the measured parameters, average speed, and distance completed. Levels of hemolysis markers were highest in horses eliminated for metabolic reasons in comparison to finishers and horses eliminated for lameness (gait abnormality), which may suggest a connection between the intensity of exercise, metabolic challenges, and hemolysis. Utilization of omics methods alongside conventional methods revealed a broader insight into the exercise-induced hemolysis process by displaying, apart from commonly measured hemoglobin and haptoglobin, levels of hemoglobin degradation metabolites. Obtained results emphasized the importance of respecting horse limitations in regard to speed and distance which, if underestimated, may lead to severe damages.

Exercise-related changes in the anabolic index (testosterone to cortisol ratio) and serum amyloid A concentration in endurance and racehorses at different fitness levels.

Increased training loads in both human and equine athletes are generally implemented to improve their physical performance. These loads are tolerated only within appropriate training periodization with regard to recovery time. Otherwise, training overload causes failure in the systemic adaptation, which at first leads to overreaching, and progressively to overtraining syndrome (OTS). Exercise endocrinology, and anabolic/catabolic balance as an indicator of athlete performance status and OTS has continued to attract attention. In human medicine, changes in testosterone and cortisol levels, as well as the testosterone to cortisol ratio (T/C; anabolic index), are suggested to be sensitive stress markers. However, there is a lack of research investigating these parameters for use in equine sports medicine. The aim of the study was to investigate the differences in testosterone, cortisol, and T/C in response to a single training session in two types of equine sports: endurance and race, together with serum amyloid A (SAA), the main acute phase response indicator of physical effort, and the overall health status in horses. Two groups of horses were enrolled in the study: endurance (n = 12) and racehorses (n = 32) of different fitness level. Blood samples were obtained before and after the exercise. On average, T increased 2.5 times after the race training in experienced racehorses and dropped in endurance horses regardless the fitness level (p < 0.05). In endurance horses, a decrease in T/C occurred after training in inexperienced horses (p < 0.05). In racehorses, a T/C decrease occurred in the inexperienced group (p < 0.05) and an increase in the experienced (p < 0.01). In conclusion, T/C ratio was found to be a potentially reliable indicator of fitness status especially in racing horses. These findings provide insight into the physiological response of the horses to different types of exercise and the potential use of hormone levels as markers of performance and adaptation.

Magnetic Resonance Imaging Measurements of the Proximal Palmar Cortex of the Third Metacarpal Bone and the Suspensory Ligament in Non-Lame Endurance Horses before and after Six Months of Training.

Proximal metacarpal injury is common in endurance horses, yet exercise-induced changes in this region have not been described. This study aimed to document objective exercise-induced changes in the proximal palmar cortex of the third metacarpal bone (PcMcIII) and the suspensory ligament (SL). Low-field magnetic resonance (MR) images of both proximal metacarpal regions were obtained from six novice and six experienced horses, before and after six months of endurance training. Measurements were acquired in T1-weighted transverse MR images at four levels and included the thickness of the PcMcIII, the mediolateral width, and the dorsopalmar depth of the entire SL and its lobes. We used t-tests or their nonparametric equivalents to compare the measurements from the two examinations and both novice and experienced horses. The medial aspect of PcMcIII was significantly thicker in experienced horses than in novice horses at 2 and 3 cm distal to the carpometacarpal joint. This likely reflects the cumulative effect of long-term exercise and possibly age. The PcMcIII was significantly thicker medially than laterally. There was no significant difference between pre- and post-season measurements. Six months of endurance training were not sufficient to induce changes in the thickness of PcMcIII or the SL that are detectable in low-field MR images.

Hydroelectrolytic and Acid-Base Parameters after 80 to 115 km Endurance Races (Raid Uruguayo) and Their Association with the Comfort Index.

The Raid Uruguayo (RAID) is an equestrian endurance competition. This study characterized the hydroelectrolytic parameters (Na+, K+, Cl-, tCa++, and iCa++), hematocrit (Ht), total plasma protein (TPP), and blood pH from 900 equine athletes (finishers and non-finishers) competing over distances of 80 to 115 km under different climate conditions. Paired blood samples were taken prior to the start of the competition (sample 1) and at the end of the race or at the time of leaving the competition (sample 2). The association of the comfort index (CI: low, moderate, and high) with blood parameters was evaluated. Of the 900 horses included, 550 were not able to finish the trial. The comfort index was not associated with success in completing the race. In the horses that finished the race, the CI was not associated with Ht, pH, TPP, or Na+ concentrations in samples taken after finishing the RAID. In contrast, the decreases in chloride, K+, tCa++, and iCa++ concentrations found after the race were more pronounced at moderate and high CI values when compared with low CI values. In horses that did not finish the race, the CI was associated with all variables except for Ht. The data confirmed the relevance of considering the impact of the comfort index in hydroelectrolytic losses in the RAID, as it influence ssuccess or failure in the performance of endurance horses finishing the competition.

Pre- and post -exercise variation of blood parameters on performance endurance horses: a first race study from Algeria

Abstract: This paper presents the first study conducted in Algeria to determine the pre and post-race hematological and biochemical parameters of horses of a 90 km endurance race for eliminated horses’ category and those who completed the races with good performance. This study was conducted on 15 endurance horses (10 Arabian Thoroughbred, 4 Arabian-Barb and 1 Barb). Nine (9) horses successfully completed the endurance race, whereas the other 6 were eliminated. Blood samples were collected from each animal before and after the end of the race. Whole blood samples were used for measuring the blood-biochemical parameters. Our results showed a significant increase in the hematological parameters (RBC, HB, Ht and MCV), the total leucocyte count, neutrophils and platelets for the group of horses who finished the race successfully. A significant decrease was noticed for the lymphocytes and eosinophils numbers while serum biochemical parameters showed a significant increase of Ca, TG, urea, U-A, AST and CK and a decrease of Mg, CHE, GLU and ƔGT. This study showed that, for the eliminated horses, there were significant changes in values of the total leucocytic count, lymphocytes, neutrophils, HB and Ht as compared to good performance horses. Serum biochemical parameters showed a significant increase of TG, U-A, AST and CK and a significant decrease of Ca, Mg, CHE and ƔGT. Most of the hemato-biochemical parameters of both the eliminated horses and those who completed the race successfully depicted significant differences. The results of this study suggested that biochemical findings could help identify horses with an increased risk of developing metabolic alterations before their elimination during competitive endurance races of different distances. Therefore, proper management protocols, standard feeding and watering with proper preparation of animals before the race could prevent electrolytes imbalance and pathological affections during racing.

Changes in novel anti-infalmmatory cytokine concetration in the bood of endurance and race horses at different levels of training

Several anti-inflammatory cytokines have been proposed as markers for exercise monitoring in humans such as the interleukin 1 receptor agonist (IL-ra), or interleukin 13 (IL-13). Equine athletes may be considered a model for human exercise physiology research, however there is a lack of such studies of this species. Thus, we decided to examine the changes of IL-1ra and IL-13 in serum concentration during aerobic (endurance) and anaerobic (race) exercise in horses of different fitness levels in comparison with the well-known anti-inflammatory cytokine interleukin 10 (IL-10). The group of endurance horses (n = 13) consisted of animals competing over 100 (n = 7) and 120 km (n = 6) rides. The group of racehorses (n = 18) consisted of trained (n = 9) and untrained (n = 9) animals. The blood samples were obtained before and after the exercise. The ELISA test was performed to evaluate the changes of IL-1ra, IL-13 and IL-10 during different types of exercise. In endurance horses there was an increase in IL-13 (p = 0.0012) after the 100 km ride and in IL-1ra (p = 0.0411) after the 120 km ride. In race horses there was a higher IL-13 basal serum concentration in the untrained group, as well as a decrease of IL-13 after exercise (p = 0.0188). In trained racehorses there was an increase in IL-1ra (p < 0.0001) and IL-13 after exercise (p = 0.0028). In conclusion, the reaction of IL-1ra and IL-13 to different types of exercise differ from each other. Thus, in future, they may be helpful in monitoring the fitness of horses, however more research is needed.

Free Swimming and Exercise-Induced Pulmonary Hemorrhage in Endurance Horses: A Preliminary Study

Swimming is used for rehabilitation of musculoskeletal injuries and for conditioning to improve equine fitness. However, there are anecdotal reports that suggest that tethered swimming can induce epistaxis, likely secondary to exercise-induced pulmonary hemorrhage (EIPH). The objective of this observational, prospective study was to investigate if EIPH occurs during intensive free-swimming training sessions (5 × 70m) using 15 endurance horses. On tracheo-bronchoscopic evaluations following swimming, low grade mucus scores were observed, but no tracheal blood was observed. Bronchoalveolar lavage fluid analysis revealed a low cellularity, and the median red blood cell count (RBCs) was 271 cells/μL (interquartile range 150–363 cells/μL), which is much lower than the threshold of RBCs >1,000 cells/μL for horses to be considered positive for EIPH. Therefore, free swimming does not seem to predispose endurance horses to EIPH following a typical free-swimming training session.