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Topic:Young Horses
Young horses are generally defined as those under five years of age, transitioning from foals to adults. Research in this area examines the study of equine development, behavior, and health across different life stages. This includes the physiological and anatomical changes that occur as horses mature from foals into adults. Additionally, understanding behavioral aspects such as socialization, learning, and adaptation to training is key to this field. This page gathers peer-reviewed research studies and scholarly articles that explore the developmental processes, health considerations, and management practices relevant to young horses and their transition into adulthood.
Influence of exercise and joint topography on depth-related spatial distribution of proteoglycan and collagen content in immature equine articular cartilage. There is ample evidence on topographical heterogeneity of the principal biochemical components of articular cartilage over the surface of the joint and the influence of loading thereon, but no information on depth-related zonal variation in horses. Objective: To study depth-related zonal variation in proteoglycan (PG) and collagen content in equine articular cartilage. Methods: Two techniques (safranin-O densitometry and Fourier transform infrared spectroscopy) were applied to sections of articular cartilage from the proximal phalangeal bone of the metacarpophalangeal joint of 18-month-old Tho...
Influence of intensity and changes of physical activity on bone mineral density of immature equine subchondral bone. Subchondral bone provides structural support to overlying articular cartilage and plays an important biomechanical role in osteochondral diseases. Mechanical features of bone correlate strongly with bone mineral density, which is directed by the loading conditions to which the tissue is subjected. Objective: To investigate the influence of physical activity levels on subchondral bone mineral density (sBMD) in foals during early development. Methods: Three groups of foals were subjected to different physical activity levels from birth until age 5 months. A proportion of these foals were subject...
Changes in mineralised tissue at the site of origin of condylar fracture are present before athletic training in Thoroughbred horses. To show that changes are present at the site of origin of metacarpal condylar fracture in young Thoroughbred horses before they enter race training. Methods: Bone slices, 2 mm thick, in three mediolateral planes through the centre of rotation of the metacarpo-phalangeal joint (MCPJ) of both distal third metacarpal bones (Mc3) of 12 Thoroughbred horses aged 17 months, were imaged using point-projection digital X-ray imaging (muXR). Results: In some horses, linear or ovoid radiolucency was found in articular calcified cartilage (ACC) and subchondral bone of the palmaro-distal aspect of the sagit...
Equine gammaherpesviruses: pathogenesis, epidemiology and diagnosis. Equine gammaherpesviruses (γEHV) have been widely studied over the past 45 years and many isolates have been characterised. Despite this, the diagnosis of γEHV infection remains difficult to establish as its clinical manifestations lack specificity, ranging from mild respiratory signs in a small number of animals to outbreaks in large groups of young horses. This review focuses on the epidemiology, pathogenesis, clinical manifestations and diagnosis of equine herpesvirus (EHV)-2 and -5 infections, as well as on the genetic variation of these viruses. Study of these variations has resulted in...
Refinement of a quantitative gene locus on equine chromosome 16 responsible for osteochondrosis in Hanoverian warmblood horses. Osteochondrosis (OC) is an inherited developmental disease in young horses most frequently observed in thoroughbreds, trotters, warmblood and coldblood horses. Quantitative trait loci (QTL) for equine OC have been identified in Hanoverian warmblood horses employing a whole genome scan with microsatellites. A QTL on ECA16 reached the genome-wide significance level for hock osteochondrosis dissecans (OCD). The aim of this study was to refine this QTL on ECA16 using an extended marker set of 34 newly developed microsatellites and 15 single nucleotide polymorphisms (SNPs). We used the same 14 pate...
Ultrastructural immunolocalization of cartilage oligomeric matrix protein (COMP) in the articular cartilage on the equine third carpal bone in trained and untrained horses. The present study was designed to delineate the presence of COMP at the ultrastructural level comparing concentrations between two areas of articular cartilage from the equine third carpal bone, subjected to different loading, from trained and untrained horses. We also analyzed the fibril thickness of collagen type II in the same compartments and zones. Samples were collected from high load-bearing areas of the dorsal radial facet (intermittent high load) and an area of the palmar condyle (low constant load) in five non-trained and three trained young racehorses. The data show that COMP is muc...
Changes in collagen fibril network organization and proteoglycan distribution in equine articular cartilage during maturation and growth. The aim of this study was to record growth-related changes in collagen network organization and proteoglycan distribution in intermittently peak-loaded and continuously lower-level-loaded articular cartilage. Cartilage from the proximal phalangeal bone of the equine metacarpophalangeal joint at birth, at 5, 11 and 18 months, and at 6-10 years of age was collected from two sites. Site 1, at the joint margin, is unloaded at slow gaits but is subjected to high-intensity loading during athletic activity; site 2 is a continuously but less intensively loaded site in the centre of the joint. The degr...
Two-dimensional- and M-mode echocardiographic measurements and indices of cardiac function in Spanish colts and fillies of different age. Echocardiographic values need to be established for each age and breed to be applied to equine medicine. The present research aims to describe echocardiographic measurements in Spanish fillies and colts of different age, to compare these values with those previously described for other equine breeds and to determine whether there is an influence of gender on echocardiographic measurements. Seventy unsedated and healthy Spanish foals of both sexes (39 females and 31 males) were divided into five age groups: A (22-60 days; n=15), B (61-90 days; n=13), C (91-180 days; n=18), D (181-270 days; n=12...
Equine grass sickness: epidemiology, diagnosis, and global distribution. Equine grass sickness (EGS) is recognized as a debilitating and predominantly fatal neurodegenerative disease affecting grazing equids. The gastrointestinal tract is the most severely affected body system, resulting in the main clinical signs of colic (acute grass sickness), weight loss, or dysphagia (chronic grass sickness). EGS predominantly occurs within Great Britain, although it is also recognized in regions of mainland Europe, and mainly affects young horses with access to pasture in the springtime. There is strong evidence of an association between EGS and the type C toxins produced by ...
Bone biomarkers and risk of fracture in two- and three-year-old Thoroughbreds. The aim of this study was to determine whether bone biomarkers (osteocalcin, PICP, ICTP and CTX-I) could be used to identify 2- and 3-year-olds at increased risk of fracture in the subsequent flat racing season. It was concluded that these bone biomarkers cannot be used to identify 2- and 3-year-olds that sustain a fracture. Whether bone biomarkers have better predictive value in older horses or when measured serially in the same animal remains to be determined.
Overtrained horses alter their resting pulsatile growth hormone secretion. The influence of intensified and reduced training on nocturnal growth hormone (GH) secretion and elimination dynamics was studied in young (1.5 yr) Standardbred geldings to detect potential markers indicative for early overtraining. Ten horses trained on a treadmill for 32 wk in age-, breed-, and gender-matched fixed pairs. Training was divided into four phases (4, 18, 6, and 4 wk, respectively): 1) habituation to high-speed treadmill trotting, 2) normal training, in which speed and duration of training sessions were gradually increased, 3) in this phase, the horses were divided into 2 groups:...
Influence of different exercise regimes on the proximal hoof circumference in young Thoroughbred horses. Most lameness in horses relates to foot problems and may be associated with changes in hoof shape, but there is a lack of information on the influence of normal exercise on hoof shape. Objective: To investigate the effect of training on proximal hoof circumference in young Thoroughbred racehorses being prepared for racing. Methods: Thirty-seven young Thoroughbred racehorses were included in this study. Front hoof circumference immediately below the coronary band was measured weekly with a measuring tape in all horses present at the stable. Most horses accomplished a minimum of 2 training perio...
Comparative long-term efficacy of ivermectin and moxidectin over winter in Canadian horses treated at removal from pastures for winter housing. The impact of a late fall treatment on the spring rise of fecal egg counts was evaluated in a controlled study with Canadian horses treated with 2 different dewormers immediately after removal from pasture for winter housing. The horses were stabled until the end of the trial period. Seventeen weanlings, 20 yearlings, and 15 2-year-old horses located in Ontario, which were presumed to be naturally infected with cyathostomins after pasture grazing, were randomly allocated to either a group treated with 0.4 mg/kg of moxidectin and 2.5 mg/kg of praziquantel or a group treated with 0.2 mg/kg of iv...
Influence of foot conformation on duration of competitive life in a Dutch Warmblood horse population. Warmblood horse studbooks aim to breed horses with a conformation that will enable elite future sports performance, but reduce the risk of early retirement due to lameness. Negative conformational traits, such as asymmetrical or 'uneven' forefeet may possibly shorten the career of sporthorses. Objective: To investigate the significance of foot conformation at young age to duration of the career of sporthorses. Methods: Databases of the Royal Dutch Warmblood Studbook (KWPN) and of the Royal Dutch Equestrian Sports Federation (KNHS) were matched and resulted in a dataset comprising 23,116 record...
Influence of early conditioning exercise on the development of gross cartilage defects and swelling behavior of cartilage extracellular matrix in the equine midcarpal joint. To investigate the influence of early conditioning exercise on the development of gross cartilage defects and swelling behavior of cartilage extracellular matrix (ECM) in the midcarpal joint of horses. Methods: 12 Thoroughbreds. Methods: 6 horses underwent early conditioning exercise from birth to 18 months of age (CONDEX group), and 6 horses were used as control animals (PASTEX group). The horses were euthanized at 18 months of age, and the midcarpal joints were harvested. Gross defects of the cartilage surface were classified and mapped. Opposing surfaces of the third and radial carpal bones...
Molecular and infection biology of the horse pathogen Rhodococcus equi. The soil actinomycete Rhodococcus equi is a pulmonary pathogen of young horses and AIDS patients. As a facultative intracellular bacterium, R. equi survives and multiplies in macrophages and establishes its specific niche inside the host cell. Recent research into chromosomal virulence factors and into the role of virulence plasmids in infection and host tropism has presented novel aspects of R. equi infection biology and pathogenicity. This review will focus on new findings in R. equi biology, the trafficking of R. equi-containing vacuoles inside host cells, factors involved in virulence and ...
A comparison of sympathetic and conventional training methods on responses to initial horse training. In 'sympathetic horsemanship' the importance of the natural behaviour of the horse and the use of body language in communication is emphasised. However, it is unclear what effect sympathetic horsemanship has on the welfare of horses. During a 5-week starting period the effect of a sympathetic (ST) versus a conventional (CT) training method was studied using 28 young Warmblood horses. Behavioural observations during the starting period as well as during a standardised final riding test were performed by trained observers. A Wilcoxon matched-pair test was used to detect differences within groups...
Blood glutathione status and activity of glutathione-metabolizing antioxidant enzymes in erythrocytes of young trotters in basic training. The aim of this study was to evaluate response of blood glutathione status and activity of glutathione-metabolizing antioxidant enzymes in erythrocytes of young trotters in basic training. Nine untrained trotters (aged 16-20 months) were exposed to a 4-month training program based on exercises at low-to-moderate intensity. The conditioning consisted of breaking the horses and running them on distances varying from 4 to 40 km a week. The workloads were increased on a 3-week basis. Exercise intensity was monitored by measuring heart rate and blood lactate. Blood samples were collected at rest, b...
Adult-young ratio, a major factor regulating social behaviour of young: a horse study. Adults play an important role in regulating the social behaviour of young individuals. However, a few pioneer studies suggest that, more than the mere presence of adults, their proportions in social groups affect the social development of young. Here, we hypothesized that aggression rates and social cohesion were correlated to adult-young ratios. Our biological model was naturally-formed groups of Przewalski horses, Equus f. przewalskii, varying in composition. Results: We investigated the social interactions and spatial relationships of 12 one- and two-year-old Przewalski horses belonging to ...
Complications of unilateral weight bearing. The most common and significant complication of excessive unilateral weight bearing in adult horses is support limb laminitis. Young horses with unilateral lameness problems develop support limb laminitis infrequently compared with adult horses.
Morphological characterization and meiotic competence of oocytes collected from filly ovaries. The effect of filly age on morphology of the ovaries, collected oocytes and their capacity for in vitro maturation (IVM) was examined. The ovaries of slaughtered fillies were classified into three groups, according to filly age: (I) <10 month old (<10MF); (II) approximately 1 year old (1YF); and (III) approximately 1.5 year old (1.5YF). The ovaries of mares were used as a control group. Ovarian morphology and collected oocytes were evaluated. Only oocytes with expanded (Ex) and compact (Cm) cumuli were used for IVM. In <10MF, 1YF, 1.5YF and mare groups, corpora lutea were found in the...
Days lost from training by two- and three-year-old Thoroughbred horses: a survey of seven UK training yards. The first major epidemiological study of injury incidence in the UK flat racing Thoroughbred (TB), published in 1985, found lameness to be the single largest reason for days when horses failed to train. It was considered advisable to ascertain if progress has been made in reducing the problem of musculoskeletal injuries in the intervening period. Objective: To quantify injury incidence and days lost from training by 2- and 3-year-old TBs in UK training yards during 2002 and 2003. Methods: One-hundred-and-eighty-two yearling TBs were recruited at the end of 2001 and daily training and injury re...
An equine joint friction test model using a cartilage-on-cartilage arrangement. This study describes an equine joint friction test using a cartilage-on-cartilage arrangement and investigates the influence of age and load on the frictional response. Osteochondral plugs were extracted from equine shoulder joints (2-5 years, n=12; 10-14 years, n=15), and mounted in a pin-on-disc tribometer. The frictional response was then measured under constant conditions (2N; 20 degrees C; 5 mm/s), and with increasing load (2N, 5N, 10N). In all experiments, the friction coefficient of young cartilage was significantly (P<0.001) smaller than obtained from old cartilage, while the applicati...
Effect of left-sided valvular regurgitation on mortality and causes of death among a population of middle-aged and older horses. The effect of left-sided valvular regurgitation (LSVR) on the mortality of middle-aged and older horses was investigated in a prospective cohort study involving 19 yards and 1153 horses. The horses were examined to determine whether they had a cardiac murmur and its type, and their age, sex, breed type and occupation were recorded. They were followed up at intervals of two years by postal questionnaire, and after four years information on 773 horses was available. There was no significant difference in the mortality of the horses with and without LSVR, but small horses had a significantly high...
Evaluation of age-related changes in the structure of the equine tarsometatarsal osteochondral unit. To investigate effects of age on thickness and morphologic characteristics of hyaline cartilage, calcified cartilage, total cartilage, and subchondral bone (SCB) in the equine tarsometatarsal joint. Methods: 23 tarsal joints from cadavers of 23 ponies (11 days to 25 years old); ponies were limited to pasture exercise and euthanatized for reasons not related to this study. Procedures-Tarsi were allocated into several age groups (11 days old [n = 3], 6 to 9 months old [4], 2 to 3 years old [3], 6 to 8 years old [4], 11 to 17 years old [6], and 20 to 25 years old [3]). Histologic examination and ...
Incidence rate of musculoskeletal injuries and determinants of time to recovery in young Australian Thoroughbred racehorses. To describe the incidence rate of musculoskeletal (MS) injuries and investigate the factors that influence recovery from MS injury in young Thoroughbred horses in Australia. Methods: Training and injury data were collected at fortnightly intervals from 14 trainers in New South Wales. Incidence rates were calculated for initial injuries stratified by age-class and sex. Survival analysis methods were used to investigate the time to recovery after the first MS injury (measured as a start in a race or barrier trial). Results: For the 248 racehorses enrolled, there were 428 injuries recorded; 2-yea...
Genetic parameters for traits evaluated at field tests of 3- and 4-year-old Swedish Warmblood horses. There are two types of 1-day field tests available for young Swedish Warmblood sport horses; one test for 3-year olds and one more advanced test for 4-year olds. Conformation, gaits and jumping ability are evaluated at both tests. Studies on various genetic parameters were based on about 20 000 tested horses. The data for 4-year olds consisted of 30 years of testing. The aims of the study were to estimate genetic parameters for results from different time periods, and to estimate heritabilities for, and genetic correlations between, traits scored in the two tests. The judgement of traits was s...
Computed tomographic anatomy of the temporomandibular joint in the young horse. The equine temporomandibular joint (TMJ) and its surrounding structures can be difficult to investigate in cases with a clinical problem related to the region. Little previous attention has been given either to a computed tomographic (CT) imaging protocol for the joint or an interpretation of the structures displayed in CT images of the normal joint. Objective: To provide a CT atlas of the normal cross-sectional anatomy of the equine TMJ using frozen and plastinated sections as anatomical reference. Methods: Eight TMJs from 4 immature pure-bred Spanish horses were examined by helical CT. Scans...
Scapulohumeral osteochondrosis. A retrospective study of 32 horses. To review the outcome of equine shoulder osteochondrosis (OC) with surgical or conservative treatment. Methods: Retrospective study of 32 horses, less than two years of age, with scapulohumeral joint (SHJ) OC. The lesion severity was graded based on measurements taken from lateromedial radiographs. Follow-up information was obtained from racing records or telephone conversations with owners. Successful outcome was defined as the ability of the horse to perform its intended use. Results: Sixteen of 32 horses were affected bilaterally (48 joints). Eleven of 16 horses with bilateral OC underwent ...
Plasma acylcarnitine and fatty acid profiles during exercise and training in Standardbreds. To evaluate alterations in skeletal muscle carnitine metabolism during exercise and training by measuring changes in plasma acylcarnitine concentrations in Standardbreds. Methods: 10 Standardbred geldings with a mean +/- SD age of 20 +/- 2 months and weight of 384 +/- 42 kg. Methods: In a 32-week longitudinal study, training on a treadmill was divided into 4 phases as follows: phase 1, acclimatization for 4 weeks; phase 2, 18 weeks with alternating endurance and high-intensity exercise training; phase 3, increased training volume and intensity for another 6 weeks; and phase 4, deconditioning f...
