Exercise-induced pulmonary haemorrhage impairs racing performance in thoroughbred racehorses

REASONS FOR PERFORMING STUDY : Exercise-induced pulmonary haemorrhage (EIPH) occurs commonly in Thoroughbred racehorses worldwide. While EIPH is believed to be an important cause of impaired performance in these horses, there is limited evidence from sufficiently powered studies to evaluate this association. OBJECTIVES : To evaluate whether EIPH is associated with finishing position, distance finished behind race winners and differences in race earning among Thoroughbred horses racing in South Africa. STUDY DESIGN : Prospective cross-sectional study. METHODS : One thousand Thoroughbred horses racing in South Africa were enrolled prior to a single race and underwent tracheobronchoscopic examination within 2 h of racing. Three observers, blinded to the horses’ identity and race performance, independently evaluated EIPH occurrence and severity using video recordings of the examination. Data were analysed using multivariable logistic and linear regression while controlling for important horse and race factors as potential confounding variables. RESULTS : Overall, 68% of horses had evidence of EIPH (grade ≥1). Horses without evidence of EIPH (severity grade 0), when compared with horses with any evidence of EIPH (grade ≥1), were >2 times more likely to win races (odds ratio = 2.3; 95% confidence interval 1.4–3.7; P = 0.001), finished an average of one length ahead of horses with EIPH (P = 0.03), and were 2.5 times more likely to be in the highest decile in race earnings (odds ratio = 2.5, 95% CI 1.5–4.1, P<0.001). However, no association was identified regarding finishing in the top 3 positions or earning money when analysed as a continuous variable or analysed as any winnings vs. none. CONCLUSIONS : Exercise-induced pulmonary haemorrhage was associated with impaired performance in Thoroughbred racehorses not medicated with furosemide and not using nasal dilator strips. These findings provide strong corroboration of previous research indicating that the occurrence of EIPH has a major impact on the ability of Thoroughbred racehorses to compete successfully as elite athletes.Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, and by the Thoroughbred Racing Trust of South Africa.http://onlinelibrary.wiley.com/journal/10.1001/(ISSN)2042-33062016-05-31hb201

Efficacy of furosemide for prevention of exercise-induced pulmonary hemorrhage in Thoroughbred racehorses

OBJECTIVE: To evaluate the efficacy of furosemide for prevention of exercise-induced pulmonary hemorrhage (EIPH) in Thoroughbred racehorses under typical racing conditions. DESIGN: Randomized, placebo-controlled, blinded, crossover field trial. ANIMALS: 167 Thoroughbred racehorses. PROCEDURES: Horses were allocated to race fields of 9 to 16 horses each and raced twice, 1 week apart, with each of the 2 races consisting of the same race field and distance. Each horse received furosemide (500 mg, IV) before one race and a placebo (saline solution) before the other, with the order of treatments randomly determined. Severity of EIPH was scored on a scale from 0 to 4 after each race by means of tracheobronchoscopy. Data were analyzed by means of various methods of multivariable logistic regression. RESULTS: Horses were substantially more likely to develop EIPH (severity score ≥ 1; odds ratio, 3.3 to 4.4) or moderate to severe EIPH (severity score ≥ 2; odds ratio, 6.9 to 11.0) following administration of saline solution than following administration of furosemide. In addition, 81 of the 120 (67.5%) horses that had EIPH after administration of saline solution had a reduction in EIPH severity score of at least 1 when treated with furosemide. CONCLUSIONS AND CLINICAL RELAVANCE: Results indicated that prerace administration of furosemide decreased the incidence and severity of EIPH in Thoroughbreds racing under typical conditions in South Africa.Supported by the National Horseracing Authority of South Africa, Phumelela Gaming and Leisure (Pty) Ltd, TecMed (Pty) Ltd, Racing South Africa (Pty) Ltd, the Grayson-Jockey Club Research Foundation, the Racing Medication and Testing Consortium, the Thoroughbred Racing Trust of South Africa, and private donors

Effect of tryptophan and of glucose on exercise capacity of horses

We hypothesized that central fatigue may have a role in limiting the endurance capacity of horses. Therefore, we tested the effect of infusing tryptophan and/or glucose on endurance time and plasma concentrations of free tryptophan and other substrates thought to affect tryptophan uptake into the brain of seven mares (3-4 yr of age, 353-435 kg) that ran on a treadmill at 50% of maximal O2 consumption to fatigue. With use of a counterbalanced crossover design, the horses were infused with tryptophan (100 mg/kg in saline solution) or a similar volume of saline solution (placebo) before exercise. During exercise, horses received infusions of glucose (2 g/min, 50% wt/vol) or a similar volume of saline. Thus the treatments were 1) tryptophan and glucose (T and G), 2) tryptophan and placebo (T and P), 3) placebo and glucose (P and G), and 4) placebo and placebo (P and P). Mean heart rate, hematocrit, and concentration of plasma total solids before and during exercise were similar for all trials. Mean time to exhaustion was reduced (P \u3c 0.05) for T and P and T and G compared with P and P [86.1 ± 6.9 and 87.1 ± 6.8 vs. 102.3 ± 10.3 (SE) min], whereas endurance for P and G (122.4 ± 11.9 min) was greater than for all other trials (P \u3c 0.05). Compared with nontryptophan trials, during the tryptophan trials plasma prolactin increased (P \u3c 0.05) nearly threefold before exercise and almost twofold early in exercise. Muscle glycogen concentrations were reduced (P \u3c 0.05) below preexercise values in the P and G and P and P trials only. However, glucose infusions (P and G) did not affect (P \u3e 0.05) concentrations of plasma free fatty acids or ratios of branched-chain amino acids to free tryptophan. In conclusion, tryptophan infusion reduced endurance time, which was consistent with the central fatigue hypothesis. The failure of glucose infusion to alleviate the effects of tryptophan and the absence of significant muscle glycogen reduction in the tryptophan trials suggest that the early onset of fatigue in the tryptophan trials is not due to a lack of readily available substrate

No effect of pre-exercise meal on substrate metabolism and time trial performance during intense endurance exercise

Etude sur huit hommes entraînés pour comparer les effets d'un repas riche en hydrates de carbone, en graisse ou sans calorie 3-4 heures avant l'exercice

Usefulness of a commercial equine IgG test and serum protein concentration as indicators of failure of transfer of passive immunity in hospitalized foals

Detection of failure of transfer of passive immunity (FTPI) is important in reducing morbidity and mortality in neonatal foals. We investigated the performance of a commercial equine IgG test (SNAP Foal IgG Test Kit) to diagnose FTPI in hospitalized foals. Furthermore, we evaluated the usefulness of serum total protein (STP) and serum globulin (SG) concentrations as indicators of FTPI. Serum IgG concentration was measured by means of the SNAP test and single radial immunodiffusion, and SG and STP concentrations were determined by means of a clinical chemistry analyzer. Subjects were 67 hospitalized foals .05) by plasma fibrinogen concentration, sepsis score, or bacteremia. Specificity for detection of [IgG] < or = 800 mg/dl was lower (P < .05) in foals with sepsis score < or =11 (50% [31-60%] versus 100% [8-100%]) and bacteremia (25% [5-56%] versus 62% [45-62%]). Sensitivity and specificity of [STP] < or = 5.0 g/dl for [IgG] < or =800 mg/dl was 94% (83-99%) and 47% (30-56%), respectively. Performance of the SNAP test in hospitalized foals is impaired because of low specificity, but can have usefulness provided that the properties of the test and characteristics of the foal being examined are considered when interpreting the results. The STP and SG concentrations are poor sole indicators of FTPI in hospitalized foals, but may be useful adjunctive tests

Dietary composition influences short-term endurance training-induced adaptations of substrate partitioning during exercise

Un régime de dix jours riche en graisse augmente substantiellement l'oxydation des lipides pendant l'exercice lorsqu'il est combiné à un entraînement aérobie quotidien. Le régime (qu'il soit riche en graisse ou hydrates de carbone) n'affecte pas l'amélioration à court terme de la performance liée à l'entraînement lors d'un test à intensité élevée