Dehydration, electrolyte imbalances and renin-angiotensin-aldosterone-vasopressin axis in successful and unsuccessful endurance horses.

REASON FOR PERFORMING STUDY: Limited information exists concerning the defence of homeostasis during endurance competitions and the relationship with performance. OBJECTIVES: This research analysed renin (REN), angiotensin II (ANG), aldosterone (ALD) and vasopressin (AVP) in horses covering different distances, assesses differences between successful and eliminated horses and evaluates correlations between hydration status, renal function, electrolytes, REN, ANG, ALD and AVP. METHODS: Packed cell volume (PCV), velocity and serum concentrations of REN, ANG, ALD, AVP, Na, K, Cl, Ca, Mg, P, creatine kinase, aspartate aminotransferase, lactate dehydrogenase, total proteins (TSP), albumin (ALB), serum uric nitrogen (SUN), creatinine (CREAT) and lactate were analysed in both successful horses (SH) and in horses eliminated due to metabolic problems (MH). Two types of competition were studied: 91 km in one day (Competition A: 20 SH, 9 MH) and 166 km in 2 days, 83 km/day (Competition B: 10 SH and 5 MH). RESULTS: Research analysed renin was not affected by exercise, whereas ANG, ALD and AVP increased. In the SH group, resting ALD and AVP concentrations at the beginning of the second day of Competition B were higher than preride values. Vasopressin did not change during the second day of Competition B, whereas ALD progressively increased. Metabolic problems of both groups showed more evident dehydration (higher PCV, TSP, ALB, SUN and CREAT) and electrolyte alterations (more intense decreases of Na and Cl) than SH at the different sampling times. Metabolic problems presented higher ALD and AVP concentrations. Angiotensin II was higher at certain sampling times in the horses. CONCLUSIONS: Endurance horses with dehydration and electrolyte disturbances showed a more intense activation of the REN-ANG-ALD-AVP axis. POTENTIAL RELEVANCE: The study of the response of the REN-ANG-ALD-AVP axis during prolonged exercise in horses with different performance will aid to minimise the risk of metabolic diseases during competitions.

Estudio de la evolución del perfil enzimático en el músculo del toro de lidia con el entrenamiento mediante la utilización de la biopsia muscular / No disponible

No disponible

Estudio de la evolución del perfil enzimático en el músculo del toro de lidia con el entrenamiento mediante la utilización de la biopsia muscular / No disponible

No disponible

Test ergoespirométrico en el caballo pura raza español / No disponible

No disponible

Trot asymmetry in relation to physical performance and metabolism in equine endurance rides.

REASON FOR PERFORMING STUDY: Trot is a symmetric gait and asymmetry might appear or increase during endurance rides due to lameness, pain or excessive fatigue. HYPOTHESIS: To assess whether trot asymmetry increases during endurance competitions, whether it is possible to discriminate between horses with different performance and also its possible relationship with metabolism. METHODS: Fifty-eight horses were filmed at trot during the lameness examinations in the vet-gates, before the competition (BCO), and after phases 1 (at 29 km), 2 (at 59 km) and 3 (at the end of the ride, at 80 km) and stride duration (SD) measured in all 4 limbs. A locomotion symmetry index (LSI) was calculated by comparing SD in the diagonal pairs of limbs. In all the cases, the longer diagonal pair SD was compared to the shorter. Horses were classified as symmetric (SyH) when LSI was lower than mean + 2s.d. and asymmetric (ASyH) when LSI was higher than mean + 2s.d. of the data obtained in BCO. Venous samples were withdrawn in the vet-gates and PCV, WBC, creatinine, TPP, uric acid, CK, AST, LDH, Na, K and Cl were measured. Horses were divided into different performance groups: successful (SH), lame (LH) and metabolic (MH), and according to ride velocity, the SH group was also divided into faster finishers (FF) and slower finishers (SF). RESULTS: The percentages of SyH were high (>80%) and very similar between the different performance groups. LSI became more asymmetrical in the vet-gates, especially in the LH and MH groups. LSI presented negative correlations with the velocities during the rides and in the vet-gates and CK. The ASyH had higher velocities during the rides and plasma CK and lower velocities during the vet-gates and plasma uric acid concentrations. CONCLUSIONS: Although trot asymmetry increases during endurance events, LSI calculated comparing SD in the two diagonal pair of limbs did not allow the differentiation of horses with different performance.

Equine locomotor analysis on vet-gates in endurance events.

REASONS FOR PERFORMING THE STUDY: Fatigue during endurance rides might induce changes in gait pattern that could be difficult to distinguish from subtle lameness. OBJECTIVES: To assess changes in gait pattern en route, in fore(FL) and hindlimbs (HL) and establish differences between excellent (EP) and good performers (GP). METHODS: Seventy-five sound and fit horses that completed endurance rides of 80 km were filmed at trot in the vet-gates (VGs) prior to competitions (VGO), and at 29 km (VG1), 59 km (VG2) and 80 km (VG3). Mean gait velocity (V), stride length (SL), duration (SD) and frequency (SF) were measured. Also, stance (StD), swing (SwD), braking (BrD) and propulsion (PrD) durations were determined in the 4 limbs and expressed as % of SD. RESULTS: Horses trotted with a significant lower V at VG3 in comparison to VG0 (mean +/- s.d. 2.3 +/- 0.6 m/sec, 3.3 +/- 0.6 m/sec) and showed a shorter SL (1.5 +/- 0.4 m and 2.2 +/- 0.3 m in VG0 and VG3). Regression analysis confirmed that the reduced SL at VG3 was due to the lower V. Horses in VG3 presented longer FL-StD (46.2 +/- 4.7%, 38.1 +/- 4.6%), BrD (22.0 +/- 2.5%, 16.9 +/- 2.5%) and PrD (24.1 +/- 21%, 21.5 +/- 2.47%) compared to VG0. In VG0, HL-PrD (23.0 +/- 3.0%) and HL-BrD (18.7 +/- 1.8%) were longer than FL-PrD (21.5 +/- 2.47%) and FL-BrD (16.9 +/- 2.5%). EP showed fastest V and longer SL at VG0, and VG3 than GP (P<0.05). CONCLUSIONS: Sound endurance horses undergo changes in gait pattern during competition, mainly due to reduction of V. Some differences exist between FL and HL, and EP show higher V and SL in the VGs. POTENTIAL RELEVANCE: Understanding of the locomotor effect of fatigue will provide an objective basis for the assessment of soundness during endurance events.

Effects of training on phagocytic and oxidative metabolism of peripheral neutrophils in horses exercised in the aerobic-anaerobic transition area.

Using simple techniques, the neutrophil function, in its phagocytosis and oxidative metabolism stages, was evaluated in horses. This was done before and after moderate exercise at the aerobic-anaerobic threshold (standardized heart rate 150 beats/min and lactate level of 3.07 +/- 0.21 mmol/L). The objective was to determine whether regular training and moderate exercise improved the neutrophil function. A group of 19 horses was used; 11 of these were untrained and the remainder trained for national jumping events. The exercise test consisted of a 5 min trot followed by a 3 min gallop on a long lunge. Blood samples were taken for analysis before, immediately after and 15 min after exercise. The results showed that (a) there is a difference in the internalization of particles (PI, PP and PE) by neutrophils from trained and untrained horses at a single time point during active recovery, and PP is higher in trained horses immediately after exercise; and (b) oxidative metabolism is significantly lower in untrained animals before and 1 min after exercise. The moderate exercise at the aerobic-anaerobic threshold did not have any influence on the peripheral blood neutrophil function of the phagocytosis and oxidative metabolism of particles.

Nonspecific immune response of peripheral blood neutrophils in two horse breeds (Anglo-Arabian and Spanish-Arabian): response to exercise.

The aim of the present paper was: (1) to find out if there were any differences in the nonspecific immunological pattern of peripheral blood neutrophil between two breeds of horses (AA and SA); (2) to evaluate the effects of an exercise in the aerobic-anaerobic threshold. This has been observed in a group of 11 untrained horses (6 SA and 5 AA) of 2.5 years old. No statistically significant differences were found in the different stages of immune response between the rest and immediately after physical exercise to two breeds. However, the chemotaxis was significant higher at rest in the AA than SA breed. A positive correlation was found at rest between the phagocytic and oxidative metabolism activity for AA breed and a negative correlation too between the adherence and chemotaxis with phagocytic capacity, immediately after exercise test, for the same breed.

Benefits of moderate training to the nonspecific immune response of colts.

The aim of this work was to assess whether progressive training caused an improvement in the nonspecific immune response of colts because several unusual infections are due to defects inherent in the neutrophilic function among which respiratory diseases are a major defect in the performance of athletes taking part in professional sports activities. A group of 7 Anglo-Arabian colts belonging to the Army was selected. These animals carry out training programmes for their participation in National Jumping Competitions. During a submaximal exercise test (heart rate 150 beats/min and lactate levels maintained at aerobic-anaerobic threshold of 3 mmol/l), they were compared with 5 colts of the same breed, just beginning training exercises. Immediately after the test, the nonspecific immune capacity of neutrophilic polymorphonuclear cells was valued by adherence, chemotaxis, ingestion and digestion of foreign substances tests. The results showed significant differences between trained and nontrained animals for the adherence and foreign particle digestion tests and, beginning with a greater adherence in untrained animals, a superior effectiveness was achieved in the immune function in trained colts, whose digestive capactiy was increased with respect to the untrained ones. It was, therefore, concluded that moderate training and exercise improves and reinforces the response of the nonspecific immune system against future infections in the organisms.

Effect of training duration and exercise on blood-borne substrates, plasma lactate and enzyme concentrations in Andalusian, Anglo-Arabian and Arabian breeds.

Metabolic responses to exercise differ between Andalusian horses and other breeds, although changes in plasma muscle enzymes have not been reported and most useful information is obtained from animals subjected to different training programmes. The objectives of this study were to 1) describe the changes in plasma enzymes during exercise in different horse breeds in relation to other biochemical parameters (Experiment A) and 2) assess the effect of training duration on these measures (Experiment B). Twenty stallions, 9 Andalusian (AN), 7 Arabian (A) and 4 Anglo-Arabian (AA), age 5-10 years, were studied. They performed 3 exercise tests (ET), consisting of a warm-up of 800 m at 0.7 km/h and 4 workloads at 15, 20, 25 and 30 km/h, at respective distances of 1250, 1670, 2080 and 2500 m, with 5 min active recovery between each workload (Experiment A). Three ETs were performed at the beginning and after 2 and 6 months of training (Experiment B). Venous blood samples were collected during the ETs and plasma glucose (GLU), free fatty acids (FFA), lactate (LA), creatine kinase (CK), lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (HBHD), aspartate aminotransferase (AST), Na+, K+ and Cl- were measured. AN horses responded to exercise with greater increases in GLU, HBHD, LDH, CK and AST compared to the other breeds. An unexpected result in Experiment A was the lack of interbreed differences in plasma peak LA concentrations, since it is commonly accepted that AA and A horses have greater athletic potential. Although the glycolytic response to exercise was reduced after 2 months of training in the AA and A horses, and after 6 months of training in the AN horses, at the end of Experiment B, AN horses produced more lactate than the other 2 breeds. Most of the adaptations linked to training were found in the AN breed. The more striking changes in plasma enzyme activities corresponded to CK in AN horses after 2 months of training. The attenuation of CK response to exercise was related to lower extrafibrilar GLU utilisation with LA formation and greater fat metabolism. The results show that plasma muscle enzyme concentrations for the diagnosis of equine myopathies must be interpreted in relation to breed and training.

Skeletal muscle fibre characteristics in young and old bulls and metabolic response after a bullfight.

Fibre type composition, activities of enzymes such as citrate synthase (CS), 3-hydroxyacyl coenzyme A dehydrogenase (HAD), lactate dehydrogenase (LDH), as well as glycogen, lactate and pH levels were analysed in muscle biopsies (m. gluteus medius) obtained after bullfighting from 10 young and 10 old bulls. No changes were seen in fibre type composition between groups, but the older bulls had higher HAD and LDH activities. Low glycogen concentrations and low pH values were found in both groups, but the lactate concentration after bullfighting was higher in the older group of bulls. The histochemical stain for glycogen revealed that type IIB fibres in both young and old bulls contained more glycogen than seen in type IIA and type I fibres. These results show that young and old bulls have similar muscle fibre type composition, but the metabolic capacity differs, with a higher glycolytic capacity and lactate production in older bulls. Furthermore, it seems that the physical and emotional stress in connection with a bullfight causes a marked depletion of glycogen, especially of type I and IIA fibres.

Differential electrocardiographic study on Iberica and Duroc breeds of pig during physical maturation.

Sequential electrocardiograms were taken of 50 pigs (25 Iberica and 25 Duroc), from the ages of 5 days to 205 days. The records were analysed to establish the normal values of the different electrocardiographic intervals (RR, QRS, QT, TQ and ST intervals), the diastole/systole quotient and heart score in the first 7 months of life, as well as age-related electrocardiographic variations. In addition, it was intended to determine which of these two breeds showed the greater heart recovery capacity. Finally, positive or negative correlations between the RR interval and the electrocardiographic incidents studied were analysed. The mean values obtained for the electrocardiographic parameters were similar in the two breeds and increased with their physical maturity. Analysis of the correlation between the duration of the heart cycle and the different electrocardiographic incidents showed a positive and significant correlation, the r-values being higher for the RR interval-TQ interval correlation. There was very little correlation between RR interval and heart score in Duroc pigs and practically no correlation between the RR interval and the QRS interval in either breed.

Locomotor response to exercise in relation to plasma lactate accumulation and heart rate in Andalusian and Anglo-Arabian horses.

To establish the effect of the locomotor pattern on heart rate (HR) and plasma lactate (LA), 28 horses, 18 Andalusian (AN) and 10 Anglo-Arabian (AA), aged 3-4 years, were studied. After a warm-up period, the horses performed a four-step test at 5, 6, 7 and 8 m/s, covering 1000 m at each velocity. HR was monitored, LA was analysed at rest and after each workload, and images were filmed. The locomotor parameters determined were stride duration (SD), frequency (SF) and length (SL), step and bipedal support durations, stance (restraint and propulsion) and swing phase durations, and stride vertical component. The HR and LA were significantly higher in the AN horses from velocities of 5 m/s. Similarly, the stride vertical component was higher in the AN horses at the trot and in the leading forelimbs at the gallop. Conversely, at all the galloping velocities, swing phase duration and stride length were longer in the AA horses. Significant correlations between HR, LA and locomotor pattern were only found in the AN horses. It was concluded that the greater stride vertical component in the AN horses limits SL and the cranial advancement of the hoof, with the result that reaching a longer SL triggers an increase in HR and LA. AA horses reach a balance between SL and SF, improving the efficiency of the gait.

Locomotor, cardiocirculatory and metabolic adaptations to training in Andalusian and Anglo-Arabian horses.

The effects of two training programmes in 20 Andalusian and 12 Anglo-Arabian horses were evaluated by an increasing intensity work test at velocities of 4, 5, 6, 7 and 8 m sec(-1). Heart rate was monitored and blood samples were drawn at rest and after each velocity to analyse packed cell volume, haemoglobin concentration, plasma lactate and potassium levels. Furthermore, the programmes were video-taped and stride length, duration and frequency, stance (restraint and propulsion), swing phase durations and stride vertical component were measured. The training protocol of the Andalusian horses produced significant decreases in the cardiovascular, haematological and metabolic responses to exercise. Locomotory training adaptation consisted of an increased stride frequency and a reduced stride length and vertical stride component. The last variable was the limiting factor of stride length both before and after training in the Andalusian horses. A different training protocol for show-jumping competition in Anglo-Arabian horses failed to show significant differences in the studied parameters to the work test, although an increase in stride length at velocities of over 6 m sec(-1) was observed. Stride vertical component did not have an effect on the physiological response to exercise, either before or after training.

Cardiovascular and metabolic adaptations in horses competing in cross-country events.

The cardiovascular and metabolic response to two cross-country events (CC*: preliminary level and CC*** advanced level) were analysed in 8 male eventing horses (4 Anglo-Hunter and 4 Anglo-Arabian). This study focused on the establishment of the main metabolic pathways involved in the muscle energy resynthesis during the competitions. Heart rate (HR) was recorded throughout the CC events. Jugular venous blood samples were withdrawn before the warm-up period, immediately after the competitions and at 5 and 10 min in the recuperation period. The following haematological parameters were studied: red blood cells (RBC), packed cell volume (PCV), haemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), white blood cells (WBC), and number and percentages of lymphocytes (LYM) and granulocytes and monocytes (GRAN). One fraction of blood was centrifuged and, in plasma, lactate (LA), total plasma protein (TPP) and the rate of LA disappearance were determined. The competitions induced significant increases in RBC, Hb, PCV, MCV and TPP. Plasma LA response exceeded the anaerobic threshold of 4 mmol/l, reaching a maximum level of 13.3 mmol/l. HR ranged from 140 to more than 200 bpm, peaking at 230 bpm, revealing a limitation in the oxygen supply to the working muscles. It was concluded that muscle energy resynthesis during a CC event is provided both through oxidative processes and glycolysis with LA formation. Therefore, both stamina and power exercises are required for eventing horses.

The use of functional indexes to evaluate fitness in Andalusian horses.

The fitness of 8 Andalusian horses between 3 and 4 years of age was analysed. The animals were subjected to an exercise test on a sandy track consisting of 2 stages of different intensities. The first stage was of submaximal intensity at 4 speeds which increased progressively (4.17, 5.56, 6.94 and 8.33 m/sec.) covering a distance of 1,000 m in each level. Between each of these speeds, the horses rested for 2 min. The second stage was a maximal speed test over the same distance carried out 2 min after the ending of the maximal phase. Data of heart rate, plasma lactate concentration, velocity, PCV and pH in the blood were obtained. Maximum heart rate, maximum velocity, VLA2, VLA4, peak lactate, minimum pH and maximum PCV were considered functional indexes. A principal component enabled us to segregate horses according to their fitness and in relation to the information provided by the trainers in charge of these horses. The most discriminant variables in order to segregate horses were pHmin, VLA4, HRmax, VLA2 and Vmax. Differences between horses in relation to PCVmax were not found. The influence of each one of these functional indexes on the test exercise tolerance was discussed.

Training as an influential factor on the locomotor pattern in Andalusian horses.

The physiological and metabolic adaptations to exercise of the Andalusian horse seem to differ slightly from those found in other breeds. The authors studied the locomotor adaptation of 18 Andalusian horses to a training programme in relation to anaerobic energy metabolism, efficacy of the training programme, and changes associated with the onset of fatigue. They also tried to find out if these changes had become diminished by training. Several locomotor variables during trotting and galloping were determined and plasma lactate concentrations were measured before training and after two training periods of different lengths. While trotting after training, an increase in the duration of the restraint phase, a reduction in the propulsion phase and a decrease in the duration and length of step were observed. During galloping, training caused a reduction in stride length but an increase in stride frequency. Significant correlations were obtained between stride duration, frequency and length of step and lactate concentrations. The training might have caused a shift in metabolism from anaerobic to aerobic predominance. This reduction was coupled with a decrease in stride duration, in response to a shorter stance phase duration and an increase in stride frequency. A reduction in the fatigue level was not observed. The study concludes that this training programme was not sufficient for improving the physical capacity of Andalusian horses.

Effect of training on diverse hematologic parameters in Andalusian horses.

A study has been made of the variations experienced by the hemogram and blood volume indices in 16 Andalusian horses after carrying out an exercise test of increasing intensity consisting of 3 sequences of 1000 m each, before and after being subjected to a daily exercise programme for two months. Samples were taken by external jugular vein puncture: while at rest, within the first minute of finalizing each exercise stage and at 10 and 15 minutes of recovery. Both the red blood cells and the hematocrit value showed a significant decrease in their mean values after two months training; conversely, the hemoglobin reached higher post-training figures. Similarly, the volume indices increased their mean values with training but no significant changes for total plasma proteins were observed.

Comparative hematological study of two breeds of foals (Andalusian and Arab) subjected to exercise of progressive intensity.

Exercise-induced hematological alterations were studied in 20 four-year old foals, 11 Andalusian and 9 Arabian. They were subjected to a test exercise program consisting of 4 levels of gradually increasing intensity (15, 20, 25 and 30 km/hr) with a duration of 5 min each. Blood samples were taken during resting, after each exercise level and at 10 and 30 min of recovery from exercise. The following hematic parameters were analyzed: red blood count, hematocrit value, hemoglobin, volumetric indexes (MCV, MCH and MHCH) and total plasma proteins. The alterations as a result of the physical effort were studied as well as any possible differences between the two breeds. The Arabian foals showed higher total plasma protein concentrations when resting, after each exercise level and at 10 mins of recovery time. The other variables studied remained with similar values in the two breeds without any significant changes.

Influence of age on the ventricular activation and recuperation processes in the pig.

In order to establish if the electrical ventricular systole is affected by physical maturation, the electrocardiographic outline of 30 Landrace x White Belgian pigs was analyzed at ages of 1 day, 5, 20 and 45 days and 3, 4 1/2 and 6 months. Throughout the first 6 months of life the values for the parameters which represent the ventricular activation underwent an increase with physical maturation. The Q wave duration increased significantly from 45 days, and the R wave between 1 day and 45 days and from 4 1/2 months. The duration of the QRS complex and the QT interval experienced a significant increase from 5 days and between 5 and 45 days of age, respectively. The changes on the amplitude were most evident when using the lead V10 with which the R wave experienced the most significant increase during the first 20 days of life. With regard to the ventricular recuperation, the T wave duration underwent a gradual increase throughout the first six months of life. A similar evolution was experienced in the amplitude recorded in the aVF and V10 leads although in the latter the most significant increase took place between the 1st and 5th day of age. Likewise, the duration of the ST segment increased with physical maturation and more significantly between 5 and 45 days of age.