Topic:Age Factors
Age factors in horses encompass a range of physiological and developmental changes that occur as horses mature from foals to adults and eventually into their senior years. These factors include variations in metabolic rate, immune function, and musculoskeletal development, which can influence a horse's health, performance, and nutritional needs. Age-related changes can also affect how horses respond to medications, recover from injuries, and maintain overall vitality. Researchers study these aspects to understand better how age impacts equine health and management. This page compiles peer-reviewed research studies and scholarly articles that explore the effects of age on equine physiology, health management, and disease susceptibility.
Intervertebral disc degeneration in warmblood horses: Histological and biochemical characterization. Gross morphology of healthy and degenerated intervertebral discs (IVDs) is largely similar in horses as in dogs and humans. For further comparison, the biochemical composition and the histological and biochemical changes with age and degeneration were analyzed in 41 warmblood horses. From 33 horses, 139 discs and 2 fetal vertebral columns were evaluated and scored histologically. From 13 horses, 73 IVDs were assessed for hydration, DNA, glycosaminoglycans, total collagen, hydroxyl-lysyl-pyridinoline, hydroxylysine, and advanced glycation end-product (AGE) content. From 7 horses, 20 discs were ...
Levels of Serum Phosphorylated Neurofilament Heavy Subunit in Clinically Healthy Standardbred Horses. Neurofilaments heavy chain proteins (pNF-H) have been identified as useful serum biomarkers for humans and animals with neurologic conditions, some of which can lead to poor performance, and athletic injuries. However, there are no published reports that describe a reference range for serum pNF-H levels in healthy racehorses. This cross-sectional study was carried out to determine the serum concentration of pNF-H in 1,349 samples collected from 1,291 clinically healthy standardbred (SB) racehorses. Data on age, time of sampling (pre-race or post-race), and finishing position during a race were...
Serum cortisol in mules intended for agricultural work. Cortisol is a hormone secreted by the adrenal glands that is stimulated by physiological and pathological factors and has been studied widely in equids, but not in mules. The objectives of this study were to obtain a reference value for serum cortisol in mules destined for agricultural activities and to identify age- and gender-related differences in the value. The concentration was obtained in blood samples using a commercial sandwich ELISA specific for cortisol. The concentration was 96.3 ± 40.6 ng/ml and similar between age groups and genders.
Effects of Standardized Exercise Tests on Plasma Thyroid Hormones’ Kinetics in Standardbred Racehorses. This study examined how a standard exercise test (SET) affected (1) thyroid hormones (THs) of horses and (2) the relationship between the V of horses and TH responses to the exercise in trained Standardbred racehorses (V is the velocity run at defined conditions at which a blood lactate concentration of 4 mmol/L is determined). Twelve trained Standardbred racehorses (six stallions and six mares) performed SETs until the horses' blood lactate concentration was at or above 4 mmol/L. The horses were divided into three age groups (2, 3, and 4 years old); each group consists of 4 horses respectivel...
Spectral Doppler ultrasound in the placental development of Mangalarga Marchador mares. The aim of the study was to correlate the spectral index of the right and left uterine arteries with equine placental development in mares with advanced pregnancies. We examined 32 multiparous Mangalarga Marchador mares with gestation of 150-240 days. During pregnancy, the pulsatility index (PI) and resistance index (RI) of the uterine arteries were obtained using spectral Doppler ultrasonography, and the combined uteroplacental thickness was obtained monthly using B-mode ultrasonography. The combined uteroplacental thickness correlated with gestational time of up to 13 years of age, and the s...
Ocular abnormalities in the Icelandic horse with a focus on equine recurrent uveitis: 112 Icelandic horses living in Denmark and 26 Icelandic horses living in the United States. To describe the most common ocular abnormalities in the Icelandic horse with focus on equine recurrent uveitis (ERU) and association between ocular abnormalities and summer eczema and coat colors. Methods: A descriptive cross-sectional study. A complete physical and ophthalmic examination as well as measurement of serum titers for Leptospira serovariants was performed on Icelandic horses from Denmark (DK) and the United States (USA). Results: One hundred and twelve Icelandic horses living in DK and 26 Icelandic horses living in the United States were included in this study (total of 138 horse...
Heart rate variability before and after 14 weeks of training in Thoroughbred horses and Standardbred trotters with different training experience. Changes in heart rate and heart rate variabilty (HRV) were investigated in untrained (UT; starting their first racing season) and detrained (DT; with 1-3 years of race experience) racehorses before and after 14-week conventional training. HRV was measured at rest over 1 h between 9:00 and 10:00 AM on the usual rest day of the horses. The smallest worthwhile change (SWC) rate was calculated for all HRV parameters. UT horses had significantly higher heart rate compared to DT (P<0.001). There were no gender- or training-related differences in heart rate. The root-mean-square of successive diff...
Horses’ (Equus caballus) Ability to Solve Visible but Not Invisible Displacement Tasks Is Associated With Frustration Behavior and Heart Rate. Many frameworks have assessed the ultimate and ontogenetic underpinnings in the development of object permanence, but less is known about whether individual characteristics, such as sex or training level, as well as proximate factors, such as arousal or emotional state, affect performance in these tasks. The current study investigated horses' performance in visible and invisible displacement tasks and assessed whether specific ontogenetic, behavioral, and physiological factors were associated with performance. The study included 39 Icelandic horses aged 2-25 years, of varying training levels. ...
Age estimation of Arabian mares by incisors morphometry and dentition changes. Accurate estimation of a horse's age based on the condition of the tooth status is necessary as a scientific and artistic technique, which has not been performed so far in pure Arabian horses of Khuzestan (southern west of Iran). This study aimed to investigate the age-dependent changes in the morphology and morphometry of the incisors in Arabian mares of Khuzestan to estimate age and to compare the estimated dental age and actual age. In this study, 78 Arabian mares of Khuzestan were examined in several equestrian clubs. Then, images were taken with a digital camera from the vestibular and oc...
Assessment of anti-Müllerian hormone in mares’ transitional period and in relation to fertility in elderly mares. Anti-Müllerian Hormone (AMH) has been linked to reproductive tract abnormalities in mares and stallions. This study aimed at evaluating AMH as a biomarker for two reproductive conditions in mares. In the first part of this study, plasma AMH was evaluated as an early indicator of the onset of cyclicity in mares in the transitional period from the anovulatory phase during winter anoestrus to the cyclic phase during the breeding season. Ten mares between 8 and 17 years old were included in the experiment which lasted from mid-February until the end of April. Ovarian activity was monitored with u...
Growth and Bone Development in the Horse: When Is a Horse Skeletally Mature? 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...
Age and Body Condition Influence the Post-Prandial Interleukin-1β Response to a High-Starch Meal in Horses. Older horses and those prone to obesity may be at a higher risk for inflammation than younger and leaner counterparts. Previous research indicated a postprandial elevation in plasma concentrations of interleukin-1β (IL-1β), a pro-inflammatory cytokine, after consuming 1.2 g of non-structural carbohydrates/kilogram of body weight. However, these studies utilized horses of mixed age and body condition. The current study evaluated post-prandial IL-1β concentrations in horses specifically comparing lean to over-conditioned and middle aged to older. Our results suggest that at least two weeks of...
Does Experience Make Hucul Horses More Resistant to Stress? A Pilot Study. The aim of the study was to determine whether experience related to horse age and number of starts in championships influences stress level, measured by salivary cortisol concentration. The study involved 18 clinically healthy Hucul mares who participated in the Polish Championships for Hucul Horses. Evaluation of performance value was carried out in accordance with the guidelines specified in the breeding and genetic resources conservation program for this breed. The championship lasted two days, consisting of conformation evaluation, endurance, and Hucul path. Saliva was collected at baselin...
Age-Dependent Intestinal Repair: Implications for Foals with Severe Colic. Colic is a leading cause of death in horses, with the most fatal form being strangulating obstruction which directly damages the intestinal barrier. Following surgical intervention, it is imperative that the intestinal barrier rapidly repairs to prevent translocation of gut bacteria and their products and ensure survival of the patient. Age-related disparities in survival have been noted in many species, including horses, humans, and pigs, with younger patients suffering poorer clinical outcomes. Maintenance and repair of the intestinal barrier is regulated by a complex mucosal microenvironmen...
Evaluation of risk factors affecting strongylid egg shedding on Hungarian horse farms. In Hungary, equine parasite control is mostly based on traditional approaches involving rotational anthelmintic treatment at regular intervals. Almost no farms utilize fecal egg counts (FECs) on a regular basis to guide deworming treatments. This approach is certainly not sustainable and is the major factor responsible for the current high levels of anthelmintic resistance. The aims of this study were to statistically analyze risk factors associated with strongylid egg count magnitude and prevalence. Fecal samples and horse data (age, pasture history, stocking density, anthelmintic history) we...
Risk factors for jockey falls in Japanese Thoroughbred jump racing. Jockey safety is an important subject from a welfare perspective and public perception. This is the first retrospective case-control study that aims to identify risk factors associated with jockey falls (JF) in Thoroughbred jump races held by the Japan Racing Association (JRA). JF in 17,459 maiden-class race starts at eight racecourses from 2003 to 2017 were retrospectively reviewed. Data were extracted from a database and official accident reports maintained by the JRA. Thirteen possible risk factors were evaluated using multivariable logistic regression to identify those that were significan...
Effect of season and geographic location in the United States on detection of potential enteric pathogens or toxin genes in horses ≥6-mo-old. We investigated the effects of season and geographic location on detection of nucleic acids of potential enteric pathogens (PEPs) or their toxins (PEP-Ts) in feces of horses ≥6-mo-old in the United States. Results of 3,343 equine diarrhea PCR panels submitted to Idexx Laboratories for horses >6-mo-old were reviewed. Submission months were grouped into 4 seasons, and states were grouped into 4 geographic regions. Logistic regression was performed to assess effects of season and region on detection rates of PEPs and PEP-Ts. Agresti-Coull CIs were determined. Detection rate of was higher in...
Variation in insulin response to oral sugar test in a cohort of horses throughout the year and evaluation of risk factors for insulin dysregulation. The oral sugar test (OST) is commonly used to diagnose insulin dysregulation (ID) and equine metabolic syndrome; however, possible seasonal changes in OST results have not been evaluated. Objective: To determine the possible variation in insulin response to OST throughout the year and risk factors associated with maximum insulin concentration (InsMax) and ID. Methods: Prospective, longitudinal cohort study. Methods: The OST was performed on 29 Finnhorses every other month six times. Serum total adiponectin concentration and phenotypic variables related to obesity were also measured. Changes in...
Symmetric dimethylarginine concentrations in healthy neonatal foals and mares. Symmetric dimethylarginine (SDMA) is a renal biomarker correlated with glomerular filtration rate (GFR). Objective: Describe changes in SDMA in clinically healthy foals and their mares during the first month postfoaling. Methods: Convenience sampling of healthy periparturient Thoroughbred mares and their full-term foals from a population of client-owned horses. Methods: Serum and EDTA whole blood samples were collected from mares in their last month of pregnancy and then from mares and foals at approximately <12 hours, 48 hours, 7 days, and 30 days postbirth. Samples were processed ...
Survival Analysis of Training Methodologies and Other Risk Factors for Musculoskeletal Injury in 2-Year-Old Thoroughbred Racehorses in Queensland, Australia. Musculoskeletal injuries remain a global problem for the Thoroughbred racing industry and there is conflicting evidence regarding the effect of age on the incidence of injuries. The ideal time to commence race training is strongly debated, with limited supporting literature. There is also conflicting evidence regarding the effect of high-speed exercise on musculoskeletal injuries. There is a strong interest in developing training and management strategies to reduce the frequency of injuries. The types of musculoskeletal injuries vary between 2-year-old and older horses, with dorsal metacarpal ...
Occupational vs. non-occupational equestrians: Differences in demographics and injury patterns. Nineteen million people participate in horseback riding activities in the US, and the horse industry employs more than 460,000 full-time workers. Emergency department data suggest young female amateurs and male professionals are most at risk of death from horse-related injuries. However, there has been no investigation into factors that may increase severe injury and mortality risk in these populations. This study investigates demographics and injury pattern differences between occupational and non-occupational horse-related injuries in the US. Methods: The 2017 American College of Surgeons Na...
Investigation of equine testis contribution to vitamin D bioactivation. Although vitamin D acts in various biological processes, it plays a critical role in the maintenance of bone health, and regulates calcium homeostasis. In humans and rodents, the main tissues involved in vitamin D metabolism are the liver and the kidneys, however it has been shown that the testis has strongly participated in its bioactivation. Indeed, in these different species, enzymes metabolizing vitamin D (CYP27A1, CYP27B1 and CYP2R1) have been demonstrated in this tissue. Moreover, men with hypogonadism have shown a decrease in circulating levels of vitamin D. In equine species, the castr...
Skeletal Muscle Adaptations to Exercise Training in Young and Aged Horses. In aged humans, low-intensity exercise increases mitochondrial density, function and oxidative capacity, decreases the prevalence of hybrid fibers, and increases lean muscle mass, but these adaptations have not been studied in aged horses. Effects of age and exercise training on muscle fiber type and size, satellite cell abundance, and mitochondrial volume density (citrate synthase activity; CS), function (cytochrome c oxidase activity; CCO), and integrative (per mg tissue) and intrinsic (per unit CS) oxidative capacities were evaluated in skeletal muscle from aged (n = 9; 22 ± 5 yr) and yea...
West Nile virus seroprevalence and associated risk factors among horses in Egypt. Determination of the seroprevalence and risk factors that are associated with West Nile virus (WNV) in horses is essential for adoption of effective prevention strategies. Our objective in this study, therefore, was to determine the seroprevalence and to identify the risk factors associated with WNV infection in the most densely horse-populated governorates in Egypt. A cross-sectional study was conducted in 2018 on 930 horses, which were distributed over five governorates in the Nile delta of Egypt. The horses, which were randomly selected, were serologically tested through use of an ID screen...
Effect of Mare Age on Transcript Abundance of Connexins-37 and -43, Zona Pellucida Proteins, and Sperm Binding. Zona pellucida (ZP) proteins are important for fertilization and sperm binding and are closely associated with cumulus cells. Communication between cumulus and oocytes is facilitated by intracellular membrane channels composed of connexins. The extent aging impacts potential differences in fertilization and reductions in fertility is not well understood. This study characterized age-related differences in transcript abundance of ZP proteins and connexins in cells from ovarian follicles. Additionally, differences in sperm binding to oocytes from old and young mares was evaluated. For experiment...
Serum symmetric dimethylarginine concentration in healthy neonatal Thoroughbred foals. Symmetric dimethylarginine (SDMA) is widely used in other species as a marker of renal dysfunction and is considered a more sensitive indicator of glomerular filtration rate than creatinine. Reference ranges are established in healthy adult horses (≤14 μg/dL) and concentrations are increased in horses with acute kidney injury (median 32 μg/dL; range 15-92). Objective: To establish the normal range of SDMA concentrations in neonatal Thoroughbreds. Methods: Cross-sectional. Methods: Blood samples were collected from Thoroughbred foals <36 h old deemed healthy by physical examination. E...
[Evaluation of clinical examination parameters and a scoring system in equine colic as well as the assessment of their prognostic value]. In horses, colic is associated with relatively high mortality rates. Identification of parameters associated with poor outcome may aid in providing a more accurate prognosis. This study aimed to assess the early prognostic value towards survival of the horse based on parameters of the clinical examination. Methods: In a retrospective study (2013-2017), results of the clinical examination of horses with colic were analyzed. Obtained parameters were categorized from physiologic up to different pathophysiologic manifestations. The risk of death was calculated as odds ratios in comparison to norma...
Factors associated with racing performance and career duration for Victorian-born Thoroughbreds. The number of horses leaving the Australian Thoroughbred (TB) racing industry each year is of concern to animal welfare advocates, public and regulators. A horse's previous athletic performance is a significant driver of retirement from racing. Racehorse performance can be measured in terms of the total number of starts, duration of racing and prize money earned. This study investigated Australian racing records for the 2005 and 2010 Victorian TB foal crops to identify factors associated with total number of starts, racing career duration, prize money earned and age of last race start-up to th...
Investigation of Factors Influencing Thoroughbred Horses’ Racing Career Length in Turkey. The aim of this research was to determine the average length of a Thoroughbred horse's racing career in Turkey using survival functions of Thoroughbred horses with various characteristics. In addition, the aim was to identify risk factors that could influence the duration of a Thoroughbred horse's racing career and develop a survival model that took these factors into account. A total of 11,721 Thoroughbred horses born in 2007 and later were included in the study population. The horses involved in the study were followed for a minimum of 1 year. Kaplan-Meier analysis was used to calculate the ...
Participation of Victorian Thoroughbreds in the racing industry: a whole-of-population benchmark. The proportion of Thoroughbred (TB) horses that commence training and eventually race, is an important industry-level indicator of how successful it is at producing horses suitable for racing. It is also of interest to the wider community and is central to the issue of whether there is overbreeding in the Australian TB industry. This study investigated the training and racing records for the 2005 and 2010 Victorian TB foal crops to determine the proportion of TBs that train and race, and the age of entering training and first race start. Subsets of the foal crop were also examined to determine...