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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.
Dynamics of follicle populations and gonadotropin concentrations in fillies age two to ten months. Follicle populations and concentrations of circulating gonadotropins were studied during age 2-10 months in 10 spring-born pony fillies. Blood sampling and ultrasound scanning were done every 4 days and daily for four 30 day periods. During 5-12 weeks, FSH concentrations were lower in 6 fillies with follicles > or = 6 mm (mean +/- s.e. 1.4 +/- 0.1 ng/ml) than in 4 fillies with follicles 10 mm and gonadotropin concentrations increased. Waves of follicular growth were identified during the 30 day periods by significant increases in the diameter of the 10 largest follicles. The waves did not ...
A survey of the fertility of Icelandic stallions. Very limited information is available on the breeding performance of Icelandic stallions, let alone the effect that management practices may have had on such performance. As an extensively kept, largely genetically isolated breed of horse it provides a good model for the study of factors that affect reproductive performance without the additional complication of selective breeding, infectious infertility and breed effect. A survey was conducted using 27 Icelandic stallions covering 1590 mares within the normal Icelandic breeding system (May to September). During the season, stallions cover mar...
Analysis of risk factors for the development of equine protozoal myeloencephalitis in horses. To investigate risk factors for development of equine protozoal myeloencephalitis (EPM) in horses. Methods: Case-control study. Methods: 251 horses admitted to The Ohio State University Veterinary Teaching Hospital from 1992 to 1995. Methods: On the basis of clinical signs of neurologic disease and detection of antibody to Sarcocystis neurona or S neurona DNA in cerebrospinal fluid, a diagnosis of EPM was made for 251 horses. Two contemporaneous series of control horses were selected from horses admitted to the hospital. One control series (n = 225) consisted of horses with diseases of the neu...
Cytological identification and quantification of testicular cell types using fine needle aspiration in horses. Fifteen stallions of different breeds, age 3-11 years, had their right testicles evaluated by fine needle aspiration cytology (FNAC). Cytological analysis showed the following spermatogenic cell types: spermatogonia (1.6% +/- 1.1); spermatocyte I (3.4% +/- 2.2); spermatocyte II (0.8% +/- 0.7); early spermatids (25.5% +/- 9.5); late spermatids (37.0% +/- 9.3). Spermatozoal numbers were expressed as the spermatic index (SI = 31.5% +/- 8.5) and Sertoli cells were expressed as the Sertoli cell index (SEI = 20.9% +/- 17.0) (means +/- s.d). Identification of cell types was relatively easy and no imm...
Surgical treatment of 45 horses affected by squamous cell carcinoma of the penis and prepuce. The medical records of 45 horses treated for suspected squamous cell carcinoma of the penis and/or prepuce were reviewed. The age of 40 horses was known, and these had a mean age of 17.4 years. The duration of neoplasia was known for only 3 of the 45 horses. The results of histological evaluation of lesions, available for 35 horses, confirmed that the diseased tissue was squamous cell carcinoma. The location of gross neoplastic lesions was recorded for 43 horses; the glans penis was involved in 24 horses, the body of the penis or the inner lamina of the preputial fold in 27 horses, and the ext...
Cadmium in organs and tissues of horses slaughtered in Italy. The cadmium content of muscle, liver, kidney and blood samples from 62 horses slaughtered in Italy was investigated. Cadmium was determined by graphite furnace atomic absorption spectrometry (GFAAS) after wet digestion of the samples. The mean and median contents of all samples were (on a fresh weight basis) 75 and 41 micrograms kg-1 for muscle, 2.46 and 2.10 mg kg-1 for liver, 20.0 and 13.5 mg kg-1 for kidney. The cadmium level in blood samples was always below 6 micrograms l-1. The cadmium concentrations in muscle, liver and kidney were found to be related to the life span of the specimens a...
Influence of different exercise levels and age on the biochemical characteristics of immature equine articular cartilage. This study aimed to examine whether biochemical characteristics of juvenile articular cartilage are changing during the first year post partum and whether they can be influenced by exercise at young age. Water, glycosaminoglycan (GAG), DNA, total collagen, hydroxylysine and hydroxylysylpyridinoline (HP) content were measured in articular cartilage of 43 foals that were subdivided into 3 groups (n = 15, 14 and 14) which were subjected to different exercise regimens from one week after birth to age 5 months. At the age of 5 months all foals were weaned and 8 foals were selected randomly from eac...
Effect of age, exercise and growth rate on bone mineral density (BMD) in third carpal bone and distal radius of Dutch Warmblood foals with osteochondrosis. This study aimed a the determining bone mineral density (BMD) in the 3rd carpal bone and distal radius of foals age 5 and 11 months that had been subjected to different exercise regimens from birth until age 5 months. It was hypothesised that BMD would be greater in older animals, and that differences in exercise regimens before age 5 months would be associated with differences in BMD at both age 5 and 11 months. Epiphyseal bone tissue was available from 5 and 11 month old Warmblood foals bred from sires known to have radiographic evidence of osteochondrosis (OC). The foals were in a clinical ...
Age-related changes and effect of exercise on the molecular composition of immature equine superficial digital flexor tendons. To test the hypothesis that exercise at very young age may influence the eventual molecular composition (and hence the biomechanical properties) of tendon tissue in the horse, 43 Dutch Warmblood foals were allotted to 3 differently exercised groups (box-rest, box-rest with training and pasture exercise). Twenty-four superficial digital flexor tendons (SDFTs) were collected at age 5 months (8 from each exercise group) and the others were obtained at 11 months after an additional period of light exercise that was equal for all remaining foals and was intended to see if any induced changes would ...
Radiographic development of osteochondral abnormalities, in the hock and stifle of Dutch Warmblood foals, from age 1 to 11 months. In a longitudinal study the hocks and stifles of Dutch Warmblood foals were radiographed at age 1 month and subsequently at intervals of 4 weeks. Forty-three foals were radiographed until age 5 months and 19 foals until age 11 months. The chance for the development of osteochondrosis was enhanced by using only offspring from diseased sires with radiographically proven OC at either the intermediate ridge of the distal tibia or the lateral ridge of the femoral trochlea. The radiographic appearances of the intermediate ridge of the distal tibia, the distal aspect of the lateral trochlear ridge of...
Postnatal muscle fibre composition of the gluteus medius muscle of Dutch Warmblood foals; maturation and the influence of exercise. The fibre type composition of the deep gluteus muscle was studied in biopsies of Dutch Warmblood foals from birth until age 48 weeks. Half the foals were given box-rest, the other half received exercise consisting of an increasing number of gallop sprints. The muscle fibre types were determined using monoclonal antibodies discriminating against the following myosin heavy chain (MHC) isoforms: types I, IIa, IId, Cardiac-alpha and Developmental. During the first 48 weeks there was a consistent increase of fibres expressing types IIa MHC, replacing fibres expressing IId MHC. This change was refle...
Effects of a single day of feed restriction on changes in serum leptin, gonadotropins, prolactin, and metabolites in aged and young mares. In a variety of species, short-term feed restriction leads to rapid changes in the reproductive axis and reduces serum levels of leptin. Two experiments were performed to test the hypothesis that a single day of feed restriction in aged and young mares would cause a suppression of the gonadotropins and serum leptin concentrations. The estrous cycles of 12 aged (>eight years; Exp. 1) and eight young (<five years; Exp. 2) mares were synchronized and the mares were conditioned to twice-daily meal feeding. On the seventh day after synchronization, restricted mares (n = 6 for Exp. 1; n = 4 fo...
The effects of frusemide on racing times of Standardbred pacers. Seven hundred and eighty-eight Standardbred pacers competing in 8378 races at one racetrack were analysed to determine the effects of the administration of prerace frusemide on racing times (RT). Frusemide was administered i.v. 4 h before the race to pacers diagnosed with exercise-induced pulmonary haemorrhage (EIPH). Of the pacers, starting in the 1997 racing season, 32.5% received prerace frusemide. This study demonstrated that administration of frusemide prior to racing significantly decreased RT. There was an overall significant decrease (P<0.00001) in RT of 0.67 s. The overall RT for h...
Age-related effects of TGF-beta on proteoglycan synthesis in equine articular cartilage. The synthesis of proteoglycans was measured in normal equine articular cartilage of ages 9 months to 20 years and the effect of TGF-beta1 on this activity was investigated. The rate of incorporation of [(35)S]Na(2)SO(4) decreased with age as did the responsiveness of the tissue to the growth factor. The enhanced synthesis of proteoglycan induced at all ages by TGF-beta1 was down-regulated by IL-1 beta and retinoic acid. The expression of mRNA for TGF-beta1, 2, and 3 was also measured, and although the level of TGF-beta1 was highest at all ages, the expression of each growth factor decreased wi...
Diagnosis and management of abnormal embryonic development characterized by formation of an embryonic vesicle without an embryo in mares. To determine the incidence, ultrasonographic characteristics, and risk factors associated with embryonic development characterized by formation of an embryonic vesicle without an embryo in mares. Methods: Prevalence survey. Methods: 159 pregnant mares. Methods: From 1994 to 1998, mares between 11 and 40 days after ovulation with normal and abnormal embryonic development were examined ultrasonographically, and characteristics of each conceptus were recorded. Results: The incidence of abnormal embryonic development in mares characterized by formation of an embryonic vesicle without an embryo was...
Changes in liver copper concentration of thoroughbred foals from birth to 160 days of age and the effect of prenatal copper supplementation of their dams. To monitor the change in liver copper concentration of Thoroughbred foals from birth to 160 days of age and to determine the effects of supplementation by two injections of copper edetate given to dams in late gestation on the liver copper concentration of their foals at birth. Methods: Ten mares pregnant to the same stallion were randomised into two groups on the basis of age, liver copper concentration and expected foaling date. The treatment group mares were given 100 mg and 250 mg copper edetate intramuscularly during the ninth and tenth months of gestation respectively. Foals had liver bi...
Morphometric study of the equine navicular bone: age-related changes and influence of exercise. Navicular bones from the four limbs of 95 horses, classified in 9 categories, were studied. The effects of age on navicular bone morphometry and histomorphometry were estimated, after adjustment of the data to even out the effects of front and rear limbs, morphometrical type, sex, weight, and size. All the external measurements of the navicular bone decreased significantly with increasing age. From the histomorphometrical data, cortical bone volume decreased with age in most horses, whereas cancellous bone volume and, in particular, the marrow spaces increased. The increase in the cancellous b...
Effect of age on immunocytochemical staining characteristics of adenohypophyseal cells in Mongolian pony mares and stallions. To determine the effect of age on immunocytochemical staining characteristics of adenohypophyseal cells of Mongolian pony mares and stallions. Methods: 35 Mongolian ponies. Methods: Pituitary glands from 1- to 22-year-old horses of both sexes were collected at a commercial slaughterhouse in China and allocated into 7 groups according to age and sex: prepubertal stallions (n = 5; 1 to 2 years old), young stallions (6; 3 to 7 years old), middle-aged stallions (4; 10 to 12 years old), old stallions (5; 15 to 22 years old), young mares (3; 3 to 7 years old), middle-aged mares (5; 10 to 12 years ol...
Risk factors for equine influenza serum antibody titres in young thoroughbred racehorses given an inactivated vaccine. Young Thoroughbred racehorses (222 yearlings entering training and 246 2-year-old horses already in training) from eight flat-training yards in Newmarket, UK were used to monitor serological responses to vaccination with an inactivated influenza virus vaccine. Blood samples taken prior to and after vaccination were tested by single radial haemolysis (SRH) to determine antibody titres (expressed as area of haemolysis in mm(2)). Prior to vaccination, yearlings had mean antibody titres (64+/-4 mm(2)) that were approximately half of those of 2-year-olds (115+/-3 mm(2)) and 89% of yearlings and 73%...
Morphology and amplitude values of the electrocardiogram of Spanish-bred horses of different ages in the Dubois leads system. The aim of this work was to record the modifications of the form and amplitude of the electrocardiographic tracings during growth using the Dubois system and to study its sensibility to these physiological changes. This work was carried out on 179 healthy, young and adult Spanish-bred horses (98 females and 81 males). One electrocardiogram (ECG) was obtained from each horse using the Dubois leads system. The bifid shape deflection of the P wave was generally more frequent than the simple one in animals at 4 months of age or older. Amplitudes of the P2 component and of the simple positive wave ...
Study of the hyaloid apparatus in the neonatal thoroughbred foal. Over 80 per cent of 169 neonatal thoroughbred foals had some part of the hyaloid artery present bilaterally and its degree of completeness, colour and character was statistically symmetrical. The complete artery was present in over 60 per cent of the foals. The incidence of the hyaloid artery and its completeness, colour and character were related to the age of the foal. The hyaloid system atrophies in the early stages of the neonatal period and generally its presence did not cause any significant ocular problems. The presence and morphology of the posterior pupillary membrane was highly corre...
Functional adaptation of equine articular cartilage: the formation of regional biochemical characteristics up to age one year. Biochemical heterogeneity of cartilage within a joint is well known in mature individuals. It has recently been reported that heterogeneity for proteoglycan content and chondrocyte metabolism in sheep develops postnatally under the influence of loading. No data exist on the collagen network in general or on the specific situation in the horse. The objective of this study was to investigate the alterations in equine articular cartilage biochemistry that occur from birth up to age one year, testing the hypothesis that the molecular composition of equine cartilage matrix is uniform at birth and b...
Effect of age and training on murmurs of atrioventricular valvular regurgitation in young thoroughbreds. Cardiac auscultation was carried out on 111 Thoroughbred horses age 2-5 years to test the hypothesis that athletic training might influence the development of atrioventricular (AV) valve regurgitation in young Thoroughbreds. Murmurs of valvular regurgitation were identified and graded on a 1-6 scale. There were 2 sources of auscultation data: 1) 55 2-year-old horses that were examined by auscultation before training commenced and 9 months later when at race fitness; 2) 56 horses age 2-5 years that were examined on one occasion only (25 2-year-olds, 23 3-year-olds, five 4-year-olds and five 5-y...
Radiographic and clinical survey of degenerative joint disease in the distal tarsal joints in Icelandic horses. The prevalence of degenerative joint disease (DJD) in the distal tarsal joints and the relation between radiographic and clinical signs compatible with the disease were estimated in a population of Icelandic horses used for riding. The material consisted of 614 horses age 6-12 years (mean age = 7.9 years). Radiographs with 3 projections of each tarsus were made and a clinical examination, including palpation of the medial aspect of the distal tarsus and motion evaluation of the hindlimbs before and after a flexion test of the tarsus, was performed. Radiographic signs of DJD in the distal tarsa...
Corneal thickness, intraocular pressure, and optical corneal diameter in Rocky Mountain Horses with cornea globosa or clinically normal corneas. To compare corneal thickness, intraocular pressure, and optical corneal diameter in Rocky Mountain Horses with cornea globosa and those with clinically normal corneas. Methods: 129 Rocky Mountain Horses. Methods: Ultrasonic pachymetry was used to measure corneal thickness. Applanation tonometry was used to measure intraocular pressure. A Jameson caliper was used to measure optical corneal diameter. Results: The central and temporal peripheral portions of the cornea were significantly thicker in horses with cornea globosa than in horses with clinically normal corneas, but corneal thicknesses in...
Factors associated with time until first race and career duration for Thoroughbred racehorses. To determine whether sex or foaling period were associated with time to first race start and whether sex, age at time of first race start, or inter-race period were associated with career duration for Thoroughbred racehorses in Australia. Methods: 553 Thoroughbred racehorses. Methods: Race records through to the end of the 6-year-old racing season were obtained for each horse. Product-limit survival analysis was used to determine whether sex or foaling period was associated with time to first race start and whether sex or age at first race was associated with career duration. A Cox proportiona...
Association of high-speed exercise with racing injury in thoroughbreds. To determine the association between high-speed exercise and risk of injury while racing among Thoroughbreds in Kentucky. Methods: Matched case-control study. Methods: 206 Thoroughbreds that sustained a musculoskeletal injury while racing and 412 Thoroughbreds that were not injured during the same races. Methods: Data regarding official timed workouts and races and the Beyer's numbers for the 3 races before the race during which injury occurred were extracted from past performance charts and compared between injured horses and control horses. Results: For injured horses, cumulative distance of...
Shape, orientation and spacing of the primary epidermal laminae in the hooves of neonatal and adult horses (Equus caballus). Circumferential and proximodistal variations in the morphology of the primary epidermal laminae of six neonatal and five adult equine feet were documented. Three parameters were quantified: interlaminar spacing, the orientation of the laminae with respect to the overlying wall, and any angulation within the laminae themselves ('internal angle'). In adult feet, the laminae were most closely spaced at the dorsum, the spacing increasing gradually towards the heels. In foals there was a non-significant trend for the dorsal laminae to be more widely spaced than those in more caudal parts of the foo...
The study of cutaneous melanomas in Camargue-type gray-skinned horses (2): epidemiological survey. An epidemiological survey was made on cutaneous melanomas occurring in Camargue-type, gray-skinned horses in southern France. The population investigated was composed of 264 horses, which were selected from the Camargue horse stud registry and were allowed to be examined by the owners. The presence of tumors was inspected macroscopically according to the standardized protocols of veterinary medicine specialists, and some tumors were subjected to macroscopic histopathological examination. The results indicated that: 1) the prevalence of melanomas in the overall population was 31.4%; 2) the odds...
Molecular cloning of equine transforming growth factor-beta1 reveals equine-specific amino acid substitutions in the mature peptide sequence. This study cloned and sequenced equine transforming growth factor (TGF)-beta1, yielding a unique nucleotide structure which predicted amino acid substitutions not seen in other mammalian species. The nucleotide sequence homology was 89% to bovine, 91% to man, 90% to ovine, and 86% to rat. Derived amino acid sequence comparison showed that the equine protein was unique, differing by two residues from man, cow, sheep, pig, and dog, and by three residues in the rat. Subsequent use of the cDNA clones to examine the expression of the TGF-beta1 gene in various tissues indicated predominant expressio...
