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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.
Immunolocalization of insulin-like growth factor-I (IGF-I) and its receptors (IGF-IR) in the equine epididymis. Insulin-like growth factor plays a paracrine/autocrine role in regulating testicular function in the stallion, but its presence in the equine epididymis remains unknown. The aim of this study was to test the hypothesis that insulin-like growth factor-I (IGF-I) and IGF-I receptor (IGF-IR) are localized in the caput, corpus, and cauda of the epididymis in an age-dependent manner. Immediately after castration, epididymal tissue was fixed, paraffin-embedded, and processed for immunohistochemistry (IHC). Western blot was also performed using equine epididymal extracts to verify the specificity of t...
Ultrasonographic visualization of the liver in sites recommended for blind percutaneous liver biopsy in horses. To ascertain the frequency of ultrasonographic identification of liver at sites recommended for blind percutaneous liver biopsy in middle-aged horses and to determine whether the liver is obscured by other organs or too thin for safe sample collection at recommended locations. Methods: Prospective case series. Methods: 36 healthy middle-aged (between 3 and 18 years old) Quarter Horses or Quarter Horse crosses [Corrected]. Methods: Blood samples were collected from each horse and submitted for evaluation of liver function. Horses with any indication of liver dysfunction on serum biochemical ana...
Pharmacokinetics of metronidazole in foals: influence of age within the neonatal period. Neonatal foals have unique pharmacokinetics, which may lead to accumulation of certain drugs when adult horse dosage regimens are used. Given its lipophilic nature and requirement for hepatic metabolism, metronidazole may be one of these drugs. The purpose of this study was to determine the pharmacokinetic profiles of metronidazole in twelve healthy foals at 1-2.5 days of age when administered as a single intravenous (IV) and intragastric (IG) dose of 15 mg/kg. Foals in the intravenous group were studied a second time at 10-12 days of age to evaluate the influence of age on pharmacokinetics wi...
UTF1, a putative marker for spermatogonial stem cells in stallions. Spermatogonial stem cells (SSCs) continuously undergo self-renewal and differentiation to sustain spermatogenesis throughout adulthood in males. In stallions, SSCs may be used for the production of progeny from geldings after cryopreservation and therapy for infertile and subfertile stallions. Undifferentiated cell transcription factor 1 (UTF1) is a putative marker for undifferentiated spermatogonia in humans and rats. The main purposes of this study are to determine the following: 1) changes in the expression pattern of UTF1 at various reproductive stages of stallions, 2) subpopulations of sp...
Effects of age on the pharmacokinetics and selected pharmacodynamics of intravenously administered fentanyl in foals. The use of fentanyl is limited in adult horses, in part due to potential for central nervous system excitation. The pharmacokinetics and the plasma concentration-related behavioural actions of fentanyl have not been described for young foals. The goal of the present study was to describe the pharmacokinetics and behavioural effects of fentanyl following administration to the same group of foals at 3 different ages. Experimental study in healthy foals. Fentanyl was administered i.v. (4 μg/kg bwt) to a group of 9 foals on 3 separate occasions at 6–8, 20–22 and 41–42 days of age. Blood sam...
The interrelationship between anti-Müllerian hormone, ovarian follicular populations and age in mares. Anti-Müllerian hormone (AMH) is a granulosa-cell-derived glycoprotein, which plays an important inhibitory role during folliculogenesis. Concentrations of AMH are highly correlated with antral follicle counts (AFCs) in other species, which in turn are related to follicular reserve. Relatively little is known about AMH and AFC in the mare. Objective: To determine plasma AMH concentrations and AFCs in mares of different ages, to measure the repeatability of AMH concentrations and AFCs within and across oestrous cycles and to assess the relationship between plasma AMH concentrations and AFCs wit...
Age and group residence but not maternal dominance affect dominance rank in young domestic horses. We present a study focused on those factors influencing dominance position in young horses, with emphasis on the role of the mother. Horses, as other group-living polygynous mammals, form stable linear dominance hierarchies based on agonistic interactions. Higher dominance positions are believed to be connected, in both sexes, to better condition and higher reproductive success. Many variables play a role in forming the dominant-submissive relationships between horses; however, the maternal effect on the dominance position of the offspring still remains unclear, as do the possible mechanisms o...
Serum insulin-like growth factor 1 in the aging horse. Insulin-like growth factor 1 (IGF-1) has important roles in anabolic processes in the musculoskeletal system and has been reported to decrease with age in both people and horses. Objective: The objective of this study was to determine serum IGF-1 levels in the aging horse from early to late adulthood (age range 5-27 years). Methods: Healthy horses (n = 72) were used in a cross-sectional study, while 37 paired serum samples were available for a longitudinal study. Serum IGF-1 protein was determined using an ELISA kit validated for use in equine samples. Results: No association was found betw...
Evidence of Toxoplasma gondii exposure among horses in Korea. The present study investigated the seroprevalence of Toxoplasma gondii (T. gondii) antibodies by ELISA in horses reared in Korea. Serum samples were collected from 2009 through 2013 from 816 horses reared in Korea. Analysis was performed using a commercial toxoplasmosis ELISA kit to detect anti-T. gondii antibodies. Overall, 24 out of 816 horses (2.9%) were seropositive for T. gondii. The result was analyzed by age, gender, breed and region. Significant differences were observed according to breed and region (P<0.05). This is the first nationwide serological investigation of T. gondii in ho...
Interacting effects of age, density, and weather on survival and current reproduction for a large mammal. Individual-based study of natural populations allows for accurate and precise estimation of fitness components and the extent to which they might vary with ecological conditions. By tracking the fates of all 701 horses known to have lived on Sable Island, Canada, from 2009 to 2013 (where there is no predation, human interference, or interspecific competition for food), we present a detailed analysis of structured population dynamics with focus on interacting effects of intraspecific competition and weather on reproduction and survival. Annual survival of adult females (0.866 ± 0.107 [[Formu...
Effect of breeding activity on the microflora of the external genitalia and in the semen of stallions, and the relationship between micro-organisms on the skin and on the external genitalia. A possible role of breeding activities in the composition of the microbial population in stallions' external genitalia (EG) and the relationship between micro-organisms colonizing the skin of the abdomen and the ones colonizing the EG have not been studied. In experiment 1, EG microbiological samples were collected from 41 stallions used for both natural cover and semen collection (BST) and from 18 non-breeding stallions (NBST). A higher (p < 0.05) frequency of isolation of potentially pathogenic species was found for BST. Age did not influence number of micro-organism species isolated both...
Detection of bacteraemia and host response in healthy neonatal foals. Neonatal sepsis is a common problem in foals and is a primary cause of death in the post natal period. Transient bacteraemia and subsequent host responses have not been described in the equine neonate. Objective: The primary objective of this study was to determine if transient bacteraemia occurs in foals within the first 72 h of life. Additional objectives included description of bacterial organisms associated with transient bacteraemia and concurrent cytokine gene expression in healthy foals. Methods: Prospective observational study in healthy foals. Methods: Blood was aseptically collecte...
The palmar metric: A novel radiographic assessment of the equine distal phalanx. Digital radiographs are often used to subjectively assess the equine digit. Recently, quantitative and objective radiographic measurements have been reported that give new insight into the form and function of the equine digit. We investigated a radio-dense curvilinear profile along the distal phalanx on lateral radiographs we term the Palmar Curve (PC) that we believe provides a measurement of the concavity of the distal phalanx of the horse. A second quantitative measurement, the Palmar Metric (PM) was defined as the percent area under the PC. We correlated the PM and age from 544 radiograph...
Technical and physiological determinants of airway smooth muscle mass in endobronchial biopsy samples of asthmatic horses. Morphometric analyses of endobronchial biopsies are commonly performed in asthma research but little is known about the technical and physiological parameters contributing to measurement variability. We investigated factors potentially affecting biopsy size, quality, and airway smooth muscle (ASM) content in heaves, an asthma-like disease of horses. Horses with heaves in clinical exacerbation (n = 6) or remission (n = 6) from the disease and six controls were studied using a crossover design. The effect of disease status, age, bronchodilation, biopsy forceps type, and carina size on total biop...
End-to-Side Versus Side-to-Side Jejunocecostomy in Horses: A Retrospective Analysis of 150 Cases. To determine factors associated with postoperative reflux, postoperative colic, repeat celiotomy, and survival in horses after end-to-side (E2S) or side-to-side (S2S) jejunocecostomy. Methods: Retrospective, multicenter study. Methods: Horses (n = 150). Methods: Admissions, intra- and postoperative data were collected from medical records of horses that had E2S or S2S jejunocecostomy. Descriptive statistics were calculated and data were analyzed using parametric and nonparametric tests, linear and multivariate logistic regression with significance set at P < .05. Kaplan-Meier estima...
Pituitary pars intermedia dysfunction does not necessarily impair insulin sensitivity in old horses. Equine pituitary pars intermedia dysfunction (PPID) has been associated with reduced insulin sensitivity in comparison with younger adult horses; however, the difference in insulin sensitivity between horses with PPID and aged-matched controls has not been well characterized. The objective of the study was to determine if aged horses with PPID had reduced insulin sensitivity and alterations in the insulin-mediated signaling pathways in the skeletal muscle when compared with healthy aged horses. Isoglycemic hyperinsulinemic clamp procedures were conducted in 12 horses that were classified as ei...
Proteomic analysis reveals age-related changes in tendon matrix composition, with age- and injury-specific matrix fragmentation. Energy storing tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), are highly prone to injury, the incidence of which increases with aging. The cellular and molecular mechanisms that result in increased injury in aged tendons are not well established but are thought to result in altered matrix turnover. However, little attempt has been made to fully characterize the tendon proteome nor determine how the abundance of specific tendon proteins changes with aging and/or injury. The aim of this study was, therefore, to assess the protein profile of normal SDFTs ...
Evaluation of the length of competitive life in Hungarian sport horses. The aim of this study was to analyse the duration of the competitive life of jumping horses in Hungary to assess the potential for genetic evaluation and to get information about the risk factors affecting jumping performance of sport horses. The data set included lifetime performance in jumping competitions for 8475 horses born from 1992 onwards with records between 1996 and 2011 (32.7% were right-censored). Longevity was measured as the number of years spent in the competition. Discrete time survival model included fixed effects of gender, age at first competition, and the time-dependent eff...
Diurnal modulation and sources of variation affecting ventricular repolarization in Warmblood horses. Irregularities in cardiac repolarization are known to predispose for arrhythmias and sudden cardiac death in humans. The QT interval is a quantitative measurement of repolarization, and clinically, the QTc (QT interval corrected for heart rate) and Tpeak to Tend intervals (TpTe) are used as repolarization markers. To support the use of these markers in horses, we sought to describe the possible influence of the environment, time of day, day-to-day effects, T wave conformation, age, body weight (BW), and horse-to-horse variation on repolarization measurements. Methods: 12 Warmblood geldings, ag...
Antinociceptive effect of buprenorphine and evaluation of the nociceptive withdrawal reflex in foals. To elicit and evaluate the NWR (nociceptive withdrawal reflex) in 2 and 11 day old foals, to investigate if buprenorphine causes antinociception and determine if the NWR response changes with increasing age. The effect of buprenorphine on behaviour was also evaluated. Methods: Prospective, experimental cross-over trial. Methods: Nine Norwegian Fjord research foals. Methods: Buprenorphine, 10 μg kg(-1) was administered intramuscularly (IM) to the same foal at 2 days and at 11 days of age. The NWR and the effect of buprenorphine were evaluated by electromyograms recorded from the left deltoid m...
Morphometric examination of the equine adult and foal lung. To understand the mechanisms of airway inflammation associated with equine diseases such as Rhodococcus equi infection, we must identify baseline "normal" structural characteristics of the horse lung. To develop a detailed understanding of the morphology of the horse lung, we adapted and applied stereological methods to the lungs from healthy adult horses (N = 4) and 1-day (N = 5) and 30-day (N = 5) old foals. The left lung was fixed in situ by intrabronchial instillation of glutaraldehyde/paraformaldehyde fixative at 25 cm H2 O column and sampled using a fractionator design follow...
Occurrence of cardiac arrhythmias in Standardbred racehorses. Cardiac arrhythmias are a recognised but poorly characterised problem in the Standardbred racehorse. Frequency data could aid the development of cardiac arrhythmia screening programmes. Objective: To characterise the occurrence of cardiac arrhythmias in Standardbreds prior to racing and in the late post race period using a handheld, noncontinuous recording device. Methods: Prospective, observational study, convenience sampling. Methods: Noncontinuous electrocardiographic recordings were obtained over a 12 week period from Standardbred horses competing at a single racetrack. Electrocardiograms ...
The influence of age on bone metabolism in mares during late pregnancy and lactation. The concentrations of carboxyterminal cross-linked telopeptide of type I collagen (CTx), osteocalcin (OCN), parathyroid hormone (PTH) and insulin-like growth factor (IGF-I) were measured in the blood serum of two age groups of mares during late pregnancy (70-50 days before foaling), during early lactation and at the peak of lactation (10-30 and 55-80 days after foaling, respectively). During late pregnancy, the PTH was higher in older (8-19 years old), compared to younger animals (3.5-4 years old) (P < 0.05). The OCN was higher in younger group during late pregnancy (P < 0.05). IGF-I was...
Concentrations of strontium, barium, cadmium, copper, zinc, manganese, chromium, antimony, selenium and lead in the equine liver and kidneys. The concentrations of specific elements in the equine liver and kidneys are of practical relevance since horses are not only food-producing animals, but also partially serve as an indicator for the environmental pollution, as the basic feed includes plants like grass, grain and fruits. In this study, the concentrations of strontium (Sr), barium (Ba), cadmium (Cd), copper (Cu), zinc (Zn), manganese (Mn), chromium (Cr), antimony (Sb), selenium (Se) and lead (Pb) were measured in the liver, renal cortex and renal medulla of 21 horses (8 male; 13 female; aged between 5 months-28 years), using indu...
From maturity to old age: tasks of daily life require a different muscle use in horses. In vertebrates ageing is characterized by reduced viscoelasticity of the ligamentous and tendineous structures and fibre changes in muscle. Also, some vertebral joint degeneration develops with ageing. The aim of this study was to apply dynamic time warping to compare the temporal characteristics of the surface electromyography (sEMG) data and to illustrate the differences in the pattern of muscle use during tasks of daily life in old and mature horses. kinematics (24 skin markers) and sEMG measurements of neck extensors and flexors were taken in five mature horses (age 10 ± 2 years, half of...
Neonatal glucocorticoid overexposure programs pituitary-adrenal function in ponies. The present study tested the hypothesis that overexposure to endogenous glucocorticoids in neonatal life alters the reactivity of the hypothalamic-pituitary-adrenal (HPA) axis in ponies at 1 and 2 yr of age. Newborn foals received saline (0.9% NaCl, n = 8, control) or long-acting adrenocorticotropic hormone (ACTH1-24) (Depot Synacthen 0.125 mg intramuscularly twice daily, n = 9) for 5 d after birth to raise cortisol concentrations 5- to 6-fold. At 1 and 2 yr of age, HPA axis function was assessed by bolus administration of short-acting ACTH1-24 (1 μg/kg intravenous) and insulin (0.5 U/kg...
Histopathological characteristics of endometrosis in thoroughbred mares in Japan: results from 50 necropsy cases. Uteri from 50 necropsied nonpregnant Japanese Thoroughbred brood mares (1-30 years of age) were investigated to clarify the histopathological characteristics of endometrosis in Japanese Thoroughbred mares and the distribution pattern of endometrosis lesions in the uterus as a whole. Endometrosis was observed in all animals over 6 years of age and in all of the 21 mares aged over 12 years of age. The affected mares showed elastofibrosis of arteries, veins and lymphatic vessels in the uterine wall, atrophy of the uterine smooth muscle layers and hyperplasia of collagen fibers among the smooth mu...
An approach of estimating individual growth curves for young thoroughbred horses based on their birthdays. We propose an approach of estimating individual growth curves based on the birthday information of Japanese Thoroughbred horses, with considerations of the seasonal compensatory growth that is a typical characteristic of seasonal breeding animals. The compensatory growth patterns appear during only the winter and spring seasons in the life of growing horses, and the meeting point between winter and spring depends on the birthday of each horse. We previously developed new growth curve equations for Japanese Thoroughbreds adjusting for compensatory growth. Based on the equations, a parameter den...
Number, causes and destinations of horses leaving the Australian Thoroughbred and Standardbred racing industries. Significant proportions of horses leave the Australian Thoroughbred and Standardbred racing industries, which has ramifications for both the economic sustainability and the public perception of racing. The aim of this study was to quantify potential horse wastage, describe the destinations of exiting horses and identify risk factors for horses going to these destinations. Methods: Questionnaires were sent to 1258 selected Thoroughbred and 981 Standardbred trainers, with response rates of 30% and 32%, respectively. The survey investigated the role of various risk factors for wastage, including ...
Heritability of epistaxis in the Australian Thoroughbred racehorse population. Post exercise epistaxis, the manifestation of a severe form of exercise-induced pulmonary haemorrhage (EIPH), has been observed in many equine racing populations. Although multiple analyses have suggested that non-genetic factors may lead to the development of this condition, relatively little consensus has been reached regarding its genetic aetiology. The objective of this study was to provide insight into both genetic and non-genetic factors that may contribute to the expression of epistaxis in the Australian Thoroughbred racing population. Racing records and reported epistaxis occurrences w...
