The Effect of Different Physical Exercise on Plasma Leptin, Cortisol, and Some Energetic Parameters Concentrations in Purebred Arabian Horses

The Welfare of Horses Competing in Three-Barrel Race Events Is Shown to Be Not Inhibited by Short Intervals between Starts

Equestrian sports require precise animal welfare and health evaluations. To test the hypothesis that horses maintain their welfare when subjected to two three-barrel (3TB) races with 2 min intervals, an experiment was designed to evaluate their surface temperature using infrared thermography (IRT) in regions of interest (barrel, flank, neck, jaw, corner of the mouth, and ocular caruncle) and also measure blood biomarkers (hemogram, total plasma protein, fibrinogen, urea, creatinine, GGT, CK, cortisol, IL-6, and IL-1β). Ten Quarter Horses were monitored through thermography (pre-race, +1, +4, and +24 h post-race) and blood sampling (pre-race, +1, +4, and +24 h post-race). ANOVA and Tukey test at 5% were used. IRT in six regions of interest (Left/Right-barrel, flank, neck muscles) increased at +, with no differences between values recorded at +1 and +4 when compared to those measured pre-race (p > 0.05). Plasma protein, RBC count, hemoglobin, hematocrit, WBC count, neutrophils, and lymphocytes (p < 0.05) increased immediately after the races, with recovery at +1 h. Other biomarkers did not change, including cortisol, IL-6, and IL-1β (p > 0.05). Results indicate that well-conditioned 3TB horses subjected to two races at short intervals do not show changes that could be related to impaired health or welfare.

Body mass conversion and improved insulin response in Colombian Paso horses subjected to a swimming training program

Overweight and obesity in horses affect their athletic performance negatively, making it therefore necessary to develop training protocols that reduce their body fat without causing hoof injuries. The objective of the study was to describe the effect of the application of a swimming training program on metabolic and endocrine variables, in addition to evaluating the changes in subcutaneous fat thickness (SFT) in a group of overweight Colombian Paso Horses (CPHs). Six CPHs were subjected to a decreasing intensity swimming program for four months. The effect of this training on metabolic variables (i.e. aspartate aminotransferase, creatine kinase, triglycerides, cholesterol, glucose) and endocrines (cortisol and insulin) was studied every two months. Additionally, changes in the neck, lumbar, and gluteal SFTs were evaluated. The information was analysed using descriptive statistics, in addition to repeated measures analysis of variance for non-parametric data in the three training moments (P<0.1) and correlation analysis between the SFT and the metabolic and endocrine variables of interest. The swimming training program for CPHs tested in this study produced more evident redistribution of adipose tissue in the gluteal region (Initial SFT = 5.2±2.08 mm; Final SFT = 3.45±2.8 mm), conversion of body mass without weight modification, and use of energy sources such as triglycerides and increased sensitivity to insulin. A limitation of the study was that the horses were not selected according to age, nor were control animals used. In addition, the limited number of horses makes extrapolation of the results inappropriate. In conclusion, the swimming training program with decreasing intensity carried out over a four-month period modified body adipose tissue in CPHs, promoting the use of energy sources, such as triglycerides and increased insulin sensitivity.

Salivary cortisol and eye temperature changes during endurance competitions

Background

The purpose of this study was to investigate the usefulness of salivary cortisol (SC) and eye temperature measured by infrared thermography (IRT^ET) as biomarkers to manage competitions more effectively and monitor horse welfare in endurance competitions. Based on previous studies, it was hypothesised that pre-exercise baseline SC and IRT^ET would be higher in younger or less experienced horses, and that post-exercise variation from baseline would be higher in the top finishers.

Results

Salivary cortisol measured in 61 competing at qualifier 40 km and 80 km rides showed an abrupt variation (93–256% rise) of the baseline SC levels [median ± interquartile range (IQR) = 0.27 ng/dl ± 0.36] obtained at the Pre-Inspection (PI) into Vet Gate (VG)1 independently of the covered distance, but modest or even lower in the subsequent Vet Gates, e.g. VG2 or VG3. The IRT^ET measured concomitantly in 16 horses showed significant (p < 0.05) higher levels at the PI in less experienced horses participating in the 40 km ride (median ± IQR = 35.7 °C ± 1.4) than their counterparts in the 80 km ride (median ± IQR = 35.0 °C ± 1.5), but not SC. Baseline SC levels at the PI of horses classifying in the Top5 in the 40 km ride category were significantly (p < 0.05) higher median ± IQR = 0.90 ng/ml ±0.61) when compared to horses positioned from 10th position on (median ± IQR = 0.16 ng/ml ±0.40). A lower IRT^ET in the PI was correlated with better placement (p < 0.05) and those in the Top5 (median ± IQR = 33.9 °C ± 0.0) had a significantly (p < 0.5) higher variation (+ 10.65%) into the last VG.

Conclusion

Pre-exercise baseline IRT^ET levels, but not SC, were higher in less experienced horses in the 40 compared to their counterparts in the 80 km ride competitions. SC and IRT^ET showed different indications according to the competition. In the40 km ride competition, higher baseline pre-exercise SC levels seemed to be linked to a better classification outcome. In contrast, in the 80 km ride horses, the higher IRT^ET variation from pre-exercise into final Vet Gate was the parameter associated with a better performance. A more controlled environment and a larger sample are needed to confirm these results and monitor horse welfare in competitions.

The effect of repeated barrel racing on blood biomarkers and physiological parameters in Quarter Horses

The objective of this study was to evaluate barrel horses undergoing a field test with one repetition. Quarter-Horses were used (14 males and females; average age: 6.5 years old), and they ran two times for 5 min in the same field. Six different periods were evaluated: rest (T-0), immediately after the first (T-1) and second races (T-2), and after 15 (T-15), 30 (T-30) and 240 min (T-240) of recovery. Heart rate (HR), speed, distance and duration were measured using a HR monitor with GPS during the races. Blood was collected to determinate glucose, lactate, total proteins (TP), albumin, globulin, urea, creatinine, uric acid (UA), triglycerides, cholesterol, non-esterified fatty acids (NEFA), gammaglutamyltransferase (GGT), creatine kinase (CK), and cortisol concentrations, as well as to perform a haemogram. The results were analysed using ANOVA and Tukey’s tests using a P-value of 5%, and they showed a maximum HR>200 bpm after both races. The largest %HR>>170 bpm occurred in the second race (P<0.05). Glucose and lactate concentrations were elevated at T-2 (P<0.05). TP, creatinine, UA and triglycerides concentrations remained elevated at T-1, T-2 and T-30 (P<0.05). TP and creatinine concentrations returned to basal concentrations at T-30 (P>0.05), and UA and triglycerides returned to base concentrations at T-240 (P>0.05). NEFA, cholesterol, GGT and CK concentrations did not change (P>0.05). Cortisol concentrations were higher at T-2 (P<0.05) but at T-240 were similar to T-0 (P>0.05). Red blood cell concentrations and haematocrits had higher values after the second race (P<0.05). These results showed that barrel horses had intense exercise and that two races with a short rest interval between them produced similar metabolic and physiologic adaptations between races, showing that the proposed protocol may be a useful tool for field characterisation of horses’ training and may contribute to the implementation of adequate training and nutritional programs.

Does road transport influence plasma leptin concentrations in horses? Preliminary study

Transport is one of the most common stressors for horses leading to an increase in cortisol secretion. Cortisol promotes leptin synthesis and release. The aim of the study was to evaluate the effect of short transport on circulating leptin and cortisol concentrations. A total of 16 crossbred naïve horses (7 geldings, 9 mares) aged 2-11 years, and weighing 530-680 kg were included in the study. The horses were transported in a commercial horse-truck to an unknown holding pen for temporary housing. To measure plasma leptin and cortisol concentrations, three blood samples were collected from each horse: before transport, immediately after unloading from the truck, and nine hours after transport at the arrival point. Transport caused a significant increase in mean plasma cortisol concentration determined at unloading, and after nine hours of unloading, in comparison to values obtained before loading. Plasma leptin concentrations did not change during the study. In conclusion, transportation procedures did not influence plasma leptin concentration in horses, despite significantly increased cortisol release.

Relationship between serum cortisol levels and some physiological parameters following reining training session in horse

The changes of cortisol, red blood cells (RBC), hemoglobin (Hb), hematocrit (Hct), heart rate (HR), respiratory rate (RR) and rectal temperature (RT) were evaluated after a reining training session in eight Quarter Horses. All parameters were measured before exercise (T0), immediately after exercise (T1), 1 h after exercise (T2), 2 h after exercise (T3) and 24 h after exercise (T4). One-way analysis of variance (ANOVA) for repeated measures, followed Bonferroni's post hoc test, showed a significant effect of the reining training session (P < 0.0001) on cortisol, RBC, Hb, Hct, HR, RR and RT. Simple linear regression analysis showed the positive correlation (P < 0.05) between cortisol changes and variations of studied parameters in T1, T3 and T4. Exercise-induced cortisol concentrations reflect the physiological response of reining training, suggesting that the changes observed are useful to assess the performance in reining horses and their reining training adaptability.