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.

A description of veterinary eliminations within British National Endurance rides in the competitive season of 2019

Veterinary eliminations within the equestrian sport of endurance have predominantly been evaluated based on data from international competitions. However, in order to take part in international competition, each horse and rider must qualify by completing rides under their national federation. The aim of this study was to analyse the competitive data and veterinary eliminations, specifically lameness, from competitions run by the British governing body of endurance: Endurance GB, during the 2019 competitive season. Competitive results for 765 ride starts from seven different ride venues were evaluated; 81.6% (n=624) horses successfully completed the rides, with the remaining 18.4% (n=141) failing to complete the ride. The majority of horses that were unsuccessful were eliminated for lameness at veterinary inspections (n=83; 58.9%). Horses competing in single loop rides (up to 55 km rides) had a success rate of 88.6% (n=624), in contrast, horses competing in rides of three loops or more (>80 km rides) reported a decreased success rate of 61.8% (n=81). Hindlimb lameness was identified more frequently (n=50; 60.2%) compared with forelimb lameness (n=33; 39.8%). Further consideration should be given to the differences between single loop rides, where a higher percentage are presented to the veterinary panel as lame prior to the start, and multi loop rides, where a higher percentage of horses are eliminated lame during the ride and potential risk factors for the increased prevalence of hindlimb lameness observed.

Do waiting times in endurance vet gates affect the cardiac recovery index?

The cardiac recovery index (CRI) is currently a key component of veterinary inspections to assess endurance horses metabolic status and fitness. Originally published by Ridgeway, it instructs veterinarians to subtract from the first heart rate (HR1), collected when the horse is initially presented for examination, a second HR (HR2), taken 1 min after the horse starts a 125 feet (38.1 m) out and back trot to assess gait. It is widely believed that an increase of more than 4 bpm from HR1 might be an indicator of fatigue. The FEI rules instruct the veterinarians to start the stopwatch exactly 1 min after the HR1 count instead of trot start, as described previously. The aims of this study were to investigate how time delays in the vet gate affect the HR1 count and the CRI during endurance competitions, and to characterise and compare the time taken by veterinarians to measure the original version of the CRI (tCRIRIDG) and the adapted CRI used in FEI endurance events (tCRIFEI). Data from 972 veterinary inspections of horses that took place in different endurance competitions in three different venues were collected. There was no association between the time elapsed from entering the vet gate to the start of the HR1 count or from the HR1 count to the start of the trot-up and the HR1 or the CRI (P>0.05). However, larger studies involving more venues and different layouts are needed to corroborate our findings and to characterise the sensitivity and specificity of the CRI regarding the baseline heart rate. Although this study did not show an influence of waiting times on the CRI, a reduced deviation from the mean observed across all veterinarians when using the original Ridgeway guidelines to calculate the CRI (tCRIRIDG) seems to point a better time-wise consistency when this version is used.

Combining Threshold, Thurstonian and Classical Linear Models in Horse Genetic Evaluations for Endurance Competitions

The racing time and rank at finish traits are commonly used for endurance horse breeding programs as a measure of their performance. Even so, given the nature of endurance competitions, many horses do not finish the race. However, the exclusion of non placed horses from the dataset could have an influence on the prediction of individual breeding values. The objective of the present paper was to develop a multitrait model including race time (T), rank (R) and placing (P), with different methodologies, to improve the genetic evaluation in endurance competitions in Spain. The database contained 6135 records from 1419 horses, with 35% of the records not placed. Horse pedigree included 10868 animals, with 52% Arab Horses. All models included gender, age and race effect as systematic effects and combined different random effects beside the animal and residual effects: rider, permanent environmental effect, and interaction horse-rider. The kilometers per race was included as a covariate for T. Heritabilities were estimated as moderately low, ranging from 0.06 to 0.14 for T, 0.09 to 0.15 for P, and 0.07 to 0.17 for R, depending on the model. T and R appeared mostly as inverse measures of the same trait due to their high genetic correlation, suggesting that T can be ignored in future genetic evaluations. P was the most independent trait from the genetic correlations. The possibility of simultaneously processing the threshold, Thurstonian and continuous traits has opened new opportunities for genetic evaluation in horse populations, and much more practical genetic evaluations can be done to help a proper genetic selection.

A Descriptive Study of Training Methods for Fédération Equestre Internationale Endurance Horses in New Zealand

Training measures, particularly those that examine the interactions between training volume, speed, and recovery, can improve understanding of training practices that contribute to success and avoid adverse horse welfare outcomes in endurance competitions. This study describes the training of Fédération Equestre Internationale (FEI) 100-160 km level horses in New Zealand. A convenience sample of 16 participants and 25 horses were surveyed before commencement of training. Participants then reported daily data for an entire nine-month season of training and competition. Participants began their season with predetermined goals and individual training plans for each horse. They intended to use competitions for training. Competitions contributed a median of 44% [IQR, 36%-49%] of total accumulated distance (in training and competition) for each horse for the season, despite being only 11% (207/1,933) of all days worked. Most starts (80%) were in domestic-level (CEN) competition ≤80 km. Speed ranged from 2-18 km/hour on home training days to 6-18.5 km/hour in CEN competitions and 10.9-16.9 km/hour in FEI competitions. Horses were worked 34% [IQR, 21-38] of days in training, ranging from 12% to 55% for individual horses. The most common horse health problem was lameness, affecting 12/25 horses, for a median of 9 (range, 1-78) days. This study highlights the potential for CEN data as a resource to improve understanding of training and competition load, speed, and recovery and therefore reduce adverse horse welfare outcomes in FEI competitions.

Characteristics of Endurance Competitions and Risk Factors for Elimination in New Zealand during Six Seasons of Competition (2010/11-2015/16)

Simple Summary

International media has recently raised awareness about horse welfare during endurance competitions. However, much of this attention is focused on international level competitions (FEI) and little is known about domestic level competitions and their risk factors for elimination. The characteristics of endurance rides and risk factors for elimination of horses due to lameness and metabolic reasons were described by assessing the records of all competitors during six competition seasons in New Zealand (2010/11–2015/16). Endurance ride entries were dominated by lower distances (40–80 km), with the number of eliminations increasing with ride distance. The competition season was structured with the longer, more competitive rides at the end of the season, allowing the shorter, earlier rides to be used as conditioning rides. Ride distance, location and progression of the endurance season were significantly associated with eliminations due to lameness or metabolic reasons and horse age was significant for metabolic reasons only. The changing profile of endurance competitors over the years showed a decreasing number of higher level riders and subsequent increase in lower level riders competing in shorter rides. This profile with low competition speeds, demonstrates better horse welfare outcomes than seen in other parts of the world.

Abstract

The welfare of horses in endurance competitions has been the focus of recent media attention. Epidemiological studies have examined the sport at the international (FEI) level. However, much of the participation in the sport occurs at a national level in preparation for FEI level competition. The aims of this study were to describe participation in, and risk factors for elimination, from New Zealand endurance competitions. Data were collated from all endurance competitions (≥40 km) held in New Zealand during the 2010/11–2015/16 competition seasons. There were 6885 starts (n = 775 horses, n = 665 riders), horses had a median age of 9 years (IQR 6.2–10.0) and had a median of 3 (IQR 2–5) starts per season. Accumulated ride distance per season per horse decreased from a median of 240 km/horse (IQR 120–440) in 2010/11 to 180 km/horse (IQR 80–320) in 2015/16. Ride entries were dominated by the 40 km (n = 2834, 41%) and 80 km (n = 2517, 37%) distances. Eliminations increased with ride distance, from 7% in 40 km rides to 53% in the 160 km rides. Lameness accounted for the majority of eliminations (64%). The odds of elimination due to lameness were significantly associated with ride distance, location (North or South island) and time of year. The 11% of starters eliminated for metabolic reasons of the horse had increased odds of elimination associated with horse age, ride distance, location and time of year.