Does Juvenile Play Programme the Equine Musculoskeletal System?

The change in third metacarpal mid-diaphyseal radiographic dimensions in Thoroughbred foals through growth

BACKGROUND

Changes in the third metacarpal (MC3) mid-diaphyseal dimensions were measured radiographically in young Thoroughbred racehorses through race training and found to be associated with a higher risk of shin soreness. However, it is still unclear whether such negative MC3 morphologies are set congenitally or through development.

OBJECTIVE

To quantify MC3 bone dimensional changes through growth.

STUDY DESIGN

Longitudinal.

METHOD

Twenty privately owned Thoroughbred foals were radiographed bimonthly from birth to 14 months of age. Four linear MC3 parameters (proximodistal MC3 length, mid-diaphyseal dorsal and palmar cortical bone thickness, and dorsopalmar medullary width) were measured using ImageJ on lateromedial radiographs. Associations with age (growth), MC3 length, differences between left and right limbs, and between sexes were analysed separately using a linear mixed effects model.

RESULTS

The dorsal cortical bone thickness showed a positive linear relationship with growth (0.4± $$ \pm $$ 0.02 mm per month, p < 0.001, 95% CI [0.37, 0.44]) while the medullary width did not change. The relative thickness of the dorsal cortical bone thickness compared with the medullary cavity width and palmar cortical bone thickness also increased through growth (0.2± $$ \pm $$ 0.01 mm per month, p < 0.001, 95% CI [0.14, 0.19]). The dorsal cortical bone thickness was positively associated with MC3 length (0.07± $$ \pm $$ 0.0001 mm per mm increase in MC3 length, p < 0.001, 95% CI [0.05, 0.08]) and the relative thickness of the dorsal cortical bone thickness (RI) to the rest of the diaphyseal parameters (0.02± $$ \pm $$ 0.01 per mm increase in MC3 length, p = 0.01, 95% CI [0.01, 0.03]).

MAIN LIMITATIONS

A limited number of foals were included with similar breeding.

CONCLUSION

The mid-diaphyseal dorsal cortical bone thickness and proportions could be measured to monitor musculoskeletal development and identify foals at increased risk of shin soreness or those that are immature or otherwise need more time before the commencement of fast training.

Associations between turn out practices and rates of musculoskeletal disease and injury in Thoroughbred foals and yearlings on stud farms in the United Kingdom

BACKGROUND

Early-life locomotor activity during turn out may alter susceptibility to musculoskeletal disease and injury via modulation of behaviours and tissue development during growth.

OBJECTIVES

Investigate associations between turn out practices and rates of musculoskeletal disease and injury in young Thoroughbreds on stud farms in the United Kingdom.

STUDY DESIGN

Prospective cohort.

METHODS

Daily records were kept on location and duration of turn out for 134 Thoroughbred foals on six stud farms, from birth until leaving the farm or study exit. Data on veterinary-attended episodes of musculoskeletal disease or injury were collated concurrently. Average daily turn out times (hours), areas (acres) and group size (n foals) were calculated for rolling 7- and 30-day periods of age. Multivariable Cox regression, including farm as a random effect, was used to investigate associations between turn out practices and musculoskeletal disease and injury.

RESULTS

The overall incidence of musculoskeletal disease or injury was 5.3 cases/100 foal-months at risk (95% confidence interval [CI]: 4.2-6.6). Compared with 24/7 turn out, average daily turn out times of between 9 and 23 hours over a 7-day period were associated with a 4.6-fold increase in musculoskeletal injury rate (95% CI: 1.7-12.3; P < 0.001), adjusting for farm and paddock area. Each 1-acre increase in the average daily turn out area during the 4th month of life, reduced the rate of musculoskeletal disease and injury between 6 and 18 months of age by 24% (hazard ratio 0.76, 95% CI: 0.58-0.99; P < 0.001), adjusting for farm and turn out time.

MAIN LIMITATIONS

Non-random sample of participants may affect generalisability. Use of veterinary-attended events likely underestimates disease/injury rates.

CONCLUSIONS

Results suggest that disruptions or alterations to turn out time routines increase injury risk and should be avoided where possible. Turn out in larger paddocks, particularly before weaning, may confer protection against subsequent musculoskeletal disease and injury.

Motor development of stable born healthy foals during the first 24 hours

The motor development of 14 healthy foals was observed using continuous video-recording from birth to 24 h of age. An ethogram was made of behaviours of interest with behaviour quantification using CowLog software. Behaviours were divided into six main classes: main activities, attempts to get up or lie down, nursing, playing and other skills, being helped by a human, and the foal not being visible. First-time behaviours (mean, range) of early motor development after birth included going into sternal position (5.4 min, 0-34.5 min), attempting to get up (7.6 min, 0.5-34.6 min), successfully getting up (56.4 min, 27.7 min - 1 h 43.3 min), walking (1 h 1.9 min, 28.1 min - 1 h 43.4 min), nursing (1 h 49.1 min, 1 h 10.3 min - 2 h 29.7 min), shaking (31.9 min, 0.2 min - 2 h 32.7 min), running (2 h 55.6 min, 1h 33.2 min - 6 h 12.1 min), walking backwards (4 h 12.8 min, 56.9 min - 12 h 50.6 min), frolicking (4 h 52.5 min, 2 h 3 min - 15 h 18.8 min), and autogrooming (7 h 30.3 min, 43.3 min - 14 h 40.1 min). All foals made several attempts before they were able to get up for the first time (61.9, 14-103). During the first 24 h the overall duration of lying down was highest, followed by standing and walking. This information adds to the basic information for assessing normal motor development in these animals, with the potential to identify delayed development.

Influência do gênero e da idade no estágio de desenvolvimento ósseo e longevidade atlética de equinos da raça puro sangue inglês de corridas no Brasil - estudo preliminar

Resumo O impacto do exercício de alta velocidade no sistema musculoesquelético de cavalos de corrida jovens tem sido amplamente discutido devido a preocupações com a saúde e o bem-estar animal. Este estudo investigou a correlação entre idade, grau de ossificação da epífise radial distal, sexo e longevidade da carreira de cavalos Puro Sangue Inglês de corrida no Brasil de 2012 a 2015. Realizamos uma avaliação retrospectiva de 286 radiografias dorsopalmar da região radiocarpica esquerda de cavalos jovens e seu desempenho de corrida. O fechamento epifisário radial distal foi classificado em três graus decrescentes: A, B ou C. Os dados de desempenho incluíram o número de corridas disputadas, duração da carreira atlética e o número de corridas por mês. As variáveis foram submetidas à análise de regressão. No momento do exame radiográfico, os cavalos machos eram significativamente mais velhos que as fêmeas, e os cavalos com graus de fechamento epifisário diferiram com a idade. A idade na primeira corrida foi de 33,08±3,81 meses, a média de corridas disputadas foi de 18,32±15,14 corridas, a duração da carreira atlética foi de 20,37±13,82 meses e o número de corridas realizadas por mês foi de 0,93±0,46 corridas. A idade influenciou (P>0,001) o fechamento da epífise radial distal em cavalos de corrida, mas o sexo não (P=0,218 para machos e P=0,275 para fêmeas). Uma associação inversa foi observada entre a idade na primeira corrida, o número de corridas disputadas por mês e a duração da carreira atlética. A frequência de corrida e a idade na primeira corrida influenciaram a duração da carreira atlética.

Influence of age and sex on bone development and athletic career longevity of Thoroughbred racehorses in Brazil - preliminary study

Abstract The impact of high-speed exercise on the musculoskeletal system of young racehorses has been extensively discussed because of concerns regarding animal health and welfare. This study investigated the correlation between age, degree of ossification of the distal radial epiphysis, sex, and career longevity of Thoroughbred racehorses in Brazil from 2012 to 2015. We performed a retrospective evaluation of 286 dorsopalmar radiographs of the left radiocarpal region of young horses and their racing performance. Distal radial epiphyseal closure was classified into three degrees: A, B, or C. Performance data included the number of races raced, athletic career length, and the number of races per month. The variables were subjected to regression analysis. At the time of radiographic examination, male horses were significantly older than females, and horses with epiphyseal closure degrees differed with age. Age at first race was 33.08±3.81 months, the average of races raced was 18.32±15.14 races, athletic career duration was 20.37±13.82 months, and the number of races raced per month was 0.93±0.46 races. Age influenced (P>0.001) the distal radial epiphyseal closure on racehorses, but sex did not (P=0.218 for males and P=0.275 for females). An inverse association was observed between age at the first race, the number of races raced per month, and athletic career duration. The frequency of race and the age at the first race influenced athletic career duration.

The Impact of Circular Exercise Diameter on Bone and Joint Health of Juvenile Animals

Circular exercise is used in many equestrian disciplines and this study aimed to determine if circle diameter impacts juvenile animal forelimb bone and joint health. On day 0, 24 calves at 9 weeks of age were assigned the following exercise treatments: small circle (12 m clockwise), large circle (18-m clockwise), treadmill, or non-exercised control. Exercise was initiated at 1.1−1.5 m/s for 5 min/d and increased 5 min weekly until reaching 30 min/d. On day 49, synovial fluid was collected from multiple joints, cartilage was collected from the proximal surface of fused third and fourth metacarpi (MC III and IV), and forelimbs underwent computed tomography scans. A statistical analysis (PROC mixed) was performed in SAS 9.4. The inside leg of the small circle treatment had a larger MC III and IV dorsopalmar external diameter than the outside (p = 0.05). The medial proximal phalanx had a greater mediolateral diameter than the lateral proximal phalanx of the small circle treatment (p = 0.01). Fetlock nitric oxide was greater in the large circle and treadmill treatments (p < 0.0001). Cartilage glycosaminoglycan concentration was greater in the outside leg of the small circle exercise treatment than the inside leg (p = 0.03). Even at slow speeds, circular exercise diameter can impact joint and bone health, but faster speeds may have greater alterations.

Growth and Bone Development in the Horse: When Is a Horse Skeletally Mature?

Simple Summary

A comparison of the pattern of growth in the horse with definitions used to describe growth and development in humans demonstrates the same general pattern of growth. In the horse, these development periods are completed very early in life, generally by 2 years of age. Using a variety of measures to define the completion of growth and bone development, the horse enters skeletal maturity by the time it is 2 years old. There is little variation in the age of maturity across different horse breeds. These data support the hypothesis that the horse evolved to be a precocious cursorial grazer and is capable of athletic activity, and used in sport, relatively early in life.

Abstract

Within the lay literature, and social media in particular, there is often debate about the age at which a horse should be started and introduced to racing or sport. To optimize the welfare and longevity of horses in racing and sport, it is important to match exercise with musculoskeletal development and the ability of the musculoskeletal system to respond to loading. The justification for not exercising horses at a certain age is often in contrast to the scientific literature and framed, with incorrect generalizations, with human growth. This review provides a relative comparison of the growth and development of the horse to the descriptors used to define growth and development in humans. Measures of physeal closure and somatic growth demonstrate that the horse completes the equivalent of rapid infant growth by weaning (4–6 months old). At approximately 11 months old, the horse completes the equivalent of the childhood phase of growth and enters puberty. At 2 years old, the horse has achieved most measures of maturity used within the human literature, including the plateauing of vertical height, closure of growth plates, and adult ratios of back length:wither height and limb length:wither height. These data support the hypothesis that the horse evolved to be a precocious cursorial grazer and is capable of athletic activity, and use in sport, relatively early in life.

An Ethical Framework for the Use of Horses in Competitive Sport: Theory and Function

Growing ethical concern about equestrian sport is reflected in publications by regulatory authorities, animal charities, and the lay press; and in government debate and social media. However, attempts by regulators and stakeholders to address ethical issues in equine sport have been discipline specific and ad hoc. Ethical frameworks can help stakeholders to make contextual decisions about what should or should not be done in a particular situation. However, when existing animal welfare frameworks and existing sports ethics frameworks are reviewed in this paper, it becomes clear that none provide us with a suitable or sufficient tool for considering ethical issues which can arise in situations where the athlete is a non-human, non-consenting participant. This paper presents the theoretical development of a novel ethical framework, with the aim of providing stakeholders with a tool which they might apply to the consideration of the ethical questions which inevitably arise in relation to (equestrian) sport. The derivation and limitations of the ethical framework are explained. The use of the framework will serve both to underwrite the continuation of the social license to use horses in sport and also to enable those within equestrian sport to critically assess existing and proposed practices and to make welfare-improving adjustments to practice if/where necessary. The theoretical framework as presented here is currently being practically tested and refined in consultation with industry stakeholders, and that research will be submitted for publication in due course.

Cervical disc width index is a reliable parameter and consistent in young growing Dutch Warmblood horses

Intervertebral disc disease, as well as the associated alteration of the radiographic intervertebral disc space width, has been reported in horses. Disc height index (DHI) has proven to be an accurate and objective parameter in other species but data related to this parameter are lacking in horses. Therefore, the aims of this retrospective longitudinal diagnostic accuracy study were (a) to evaluate the reliability of measurements within and between observers of the equine Disc Width Index (EDWI) as a parameter for radiographic equine cervical intervertebral disc space width, and (b) to evaluate the sequential development of the EDWI over time. For this, EDWI from all intervertebral disc spaces between second cervical (C) to first thoracic (Th) vertebrae were obtained in a group of 39 Dutch Warmblood horses at 1, 5, and 18 months of age, by one European College of Veterinary Diagnostic Imaging (ECVDI) board-certified veterinary radiologist (S.V.) and two veterinary students. Bland-Altmann plots and intraclass Correlation Coefficient revealed a good intra- and interobserver agreement. A linear mixed-effect model did reveal that mean EDWI increases significantly toward the caudal cervical spine, but did not differ significantly for a certain location over time or between sexes. Spearman's rank test did show a significant correlation between the vertebral alignment angle induced by different head-neck positions and a normalized EDWI (ρ = 0.33, P < .0001). Student's t-test revealed that the presence of C6-C7 transposition of the transverse processes did not influence EDWI significantly. It was concluded that EDWI represents a reliable parameter for equine cervical radiographic intervertebral disc space width. Practical implementation of EDWI warrants monitoring in a group of adult horses while maintaining a standardized head-neck position.

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.