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.
Mortality rates and associated factors in equine colic operations – a retrospective study of 341 operations. A retrospective survey of 300 surgical treatments for colic involving 341 interventions was carried out to determine mortality rates and associated factors. These horses had been referred to the Ontario Veterinary College over the period September 1974 to February 1980. Data from the case records was collected and stored on a computer and statistical analysis was carried out using X(2) tests.Fifty percent (150/300) of the horses survived to be discharged from the hospital. Fifty-two horses were euthanized during the operation and another ten horses should have been; if these cases are excluded...
Reproducibility and the influence of age on interspecimen determinations of blood pressure in the horse. 1. The reproducibility of blood pressure determinations on 103 male horses gave an average coefficient of variation of 5.0%. 2. Different parameters affecting the methodology of blood pressure measurements were separately analysed; i.e. size of specimen, size of cuff in relationship to tail circumference and temperature of the environment. 3. A strong positive linear correlation between age and blood pressure in the horse was established for two breeds with widely varying genetic background--Swedish Warmbloods and Arabians.
Pulmonary effects of intravenous histamine in the conscious pony: dose-response relationships and reproducibility. In standing sedated ponies, we measured dynamic lung compliance (Cdyn) and pulmonary resistance (RL) during IV infusion of various doses of histamine; this was done in a given pony 3 times at 1-week intervals between experiments. Histamine doses causing a decrease in Cdyn of 50% and 75% and an increase in RL of 300% and 600% (ED50Cdyn, ED75Cdyn, ED300RL and ED600RL, respectively) were interpolated from the histamine dose-response curves. We also measured respiratory frequency, tidal volume, minute ventilation, functional residual capacity, arterial oxygen tension, arterial carbon dioxide tensi...
The prevalence of Gasterophilus intestinalis in horses in northern England and Wales. The stomachs of 448 horses from northern England and Wales were examined for Gasterophilus larvae, and 237 (52.7%) were found to be infected with G. intestinalis. Larvae were present in stomachs examined during each month of the year except August. Second instar larvae occurred from September through February and third instars were present from November through July. Adult fly activity began in August as indicated by the presence of eggs on horses. The life-cycle of G. intestinalis in northern England and Wales is outlined from the data presented. The mean instar burdens were 15.7 second and 3...
Learning ability of orphan foals, of normal foals and of their mothers. The maze learning ability of six pony foals that had been weaned at birth was compared to that of six foals reared normally. The foals' learning ability was also compared to their mothers' learning ability at the same task; the correct turn in a single choice point maze. The maze learning test was conducted when the foals were 6 to 8 mo old and after the mothered foals had been weaned. There was no significant difference between the ability of orphaned (weaned at birth) and mothered foals in their ability to learn to turn left (6 +/- .7 and 5.1 +/- .1 trials, respectively) or to learn the reve...
Study of agglutinins to Brucella abortus, B canis and Actinobacillus equuli in horses. Horses at a veterinary teaching hospital and a slaughterhouse were surveyed for antibodies to Brucella abortus, B canis and Actinobacillus equuli. Four of the 141 hospitalised horses and none of the 73 slaughtered horses had titres of 1:100 or greater to B abortus. Six horses of both populations reacted to the card test. One was culture positive. A card test using B canis antigen was positive in 38 per cent of the sera from hospitalised horses and all of the slaughtered horses. Twenty (27.4 per cent) of the latter group had high tires in a tube agglutination test. High titres could not be redu...
A comparison of chemical and electrophoretic methods of serum protein determinations in clinically normal domestic animals of various ages. The biuret total protein method and a bromcresol green (BCG) albumin method were used on the Abbott ABA-100 chemistry analyzer to assay serum proteins in clinically normal cattle, sheep, ponies, pigs, and ducks. Total proteins were also read on a refractometer and mylar supported cellulose acetate electrophoresis was performed. Globulins and A/G ratios were calculated from the chemical method and the results compared with the electrophoretic method. Total protein, albumin and A/G ratios in the ponies, sheep and older cattle were in agreement between the two methods. The younger cattle and all ...
Observations on the isoenzymes of aspartate aminotransferase in equine tissues and serum. The distribution of the isoenzymes of aspartate aminotransferase (AST, E.C. 2.6.1.1.) in equine tissues has been studied to ascertain whether the organ of origin may be identified when the total AST activity of serum is raised. Most tissues contain 3 isoenzymes of cytoplasmic origin (cAST) with isoelectric points of 5.6, 5.7 and 5.9, and one isoenzyme of mitochondrial (mAST) origin with an isoelectric point of 9. Serum from horses with azoturia contained an additional cytoplasmic subform with an isoelectric point of 5.8. This form could not be generated by ageing, freezing and thawing or bindi...
Endoscopic findings in the upper respiratory tract of 479 horses. A flexible fiberoptic endoscope was used to examine the upper respiratory tract of 479 horses and 41 (8.6%) had abnormalities. Pharyngeal lymphoid hyperplasia (PLH) was found in 141 horses (29.5%). Statistical analysis showed a relationship between the age of the horse and the prevalence of PLH. Sixteen (3.3%), 10 (2.1%), and 6 (1.3%), of the horses had laryngeal hemiplegia, epiglottic entrapment, and dorsal displacement of the soft palate, respectively. There was no association between the age of the horse and the prevalence of any of these abnormalities; nor was there a positive correlation ...
Exercise-induced pulmonary hemorrhage in Thoroughbreds after racing and breezing. Thoroughbred horses (n = 191) were examined with a flexible fiberoptic endoscope within 2 hours of racing on a dirt track; 147 (75.4%) had evidence of exercise-induced pulmonary hemorrhage (EIPH), and 13 (9.0%) had blood at the nostrils. Of 107 Thoroughbreds examined within the same period after breezing, 41 (38.3%) had evidence of EIPH. One horse (2.4%) of this group had blood at the nostrils. Statistical analysis of frequency data showed that a relationship existed between EIPH and the horse's age or distance raced or breezed. Relationship did not exist between EIPH and sex or finishing posi...
The equine electrocardiogram with standardized body and limb positions. Eleven-lead electrocardiograms (ECGs) were recorded from 50 Thoroughbred (TB) and 50 Standard bred (SB) horses at rest with 40 tracings being selected from each group for more complete analysis. Incomplete atrioventricular block with dropped beats commonly reported in mature horses was recorded only in the TB (15%), while wandering of the atrial pacemaker (WAP) thought also to be associated with variations in tone of the autonomic nervous system was detected almost equally in both breeds (30%). In some horses (12.5%), the initial component of the P wave (P1) did not vary as seen with WAP but h...
Observations on the epidemiology of equine hydatidosis in Britain. Of 1388 horses and ponies examined at two abattoirs in the north of England from November 1979 to September 1981, 123 (8.7 per cent) showed evidence of hydatid infection. Prevalence of infection was closely related to age, rising from nil in animals up to two years old to over 20 per cent of those over eight years. Full-mouthed horses and ponies had similar prevalence rates (14.9 and 14.5 per cent, respectively), but horses had nearly twice as many viable infections as ponies. The prevalence of infection varied with the region of origin of full-mouthed horses and ponies, with 18 per cent of th...
A comparison of the serum protein electrophoretic patterns of young and adult animals. Samples of serum from both young and adult normal cattle, sheep and horses were subjected to protein electrophoresis on agarose gel films. After processing, the stained electrophoretic patterns and densitometric traces of each species exhibited certain specific characteristics. The separations also revealed differences between young and adult animals of the same species. These age-related differences are described here.
Osseous cyst-like lesions of the medial femoral condyle in the horse. Osseous cyst-like lesions of the medial femoral condyle were found in 32 horses admitted to the University of Pennsylvania between 1971 and 1978. Sex or breed predilection was not found. In 12 horses, osseous cysts were found in both hindlimbs. Of the 25 horses on which follow-up information was obtained, 16 became sound and useful between 4 months and 1 year after diagnosis. Horses that became lame before 3 years of age had a better chance for later soundness. Horses that became sound had significantly smaller cysts than those that remained lame.
[Derivation and use of a new physiological criterion in the evaluation of performance in horses]. The possibility of using the test for pulse-rate response to gradated load in the evaluation of the endurance component of horse performance (in other words, response to the degree of horse adaptation to load) is discussed in detail. A mathematic-statistical analysis of regression coefficients is performed in the equations of the dependence of pulse rate on speed obtained in 278 three years old horses in the period following the termination of the basic training (145 Bohemian Warm-Blooded horses, 115 Kladrub Black horses and 18 English Half-Breds). A ten-score scale is calculated on the basis ...
Enteritis in foals induced by rotavirus and enterotoxigenic Escherichia coli. Colostrum-deprived, colostrum-fed or suckling foals were orally inoculated with foal rotavirus and enterotoxigenic Escherichia coli derived from a calf. Neither agent given alone caused diarrhoea in foals aged 1 or 2 days, although with rotavirus, 2 of the 3 inoculated foals became depressed 3 days after inoculation and all 3 were excreting rotavirus in the faeces. Inoculation of both agents induced diarrhoea in colostrum-deprived, colostrum-fed or suckling foals aged up to 16 days. There was an apparent age-related resistance to diarrhoea which developed between 2 and 3 weeks of age. It was r...
Antibodies to the zona pellucida in mares. Cross-reactivity tests indicated that the equine zona pellucida shares common antigen(s) with porcine zona. Porcine oocytes were therefore used to test for the presence of zona antibodies in the sera of horses. Serum samples were collected from 65 mares infertile for unexplained causes: 7 mares were strongly positive for antibodies reactive to porcine zona pellucida as determined by an indirect immunofluorescence method. Of these 7 mares, aged 8-23 years, 2 were nulliparous and 5 were multiparous. Zona-covered horse oocytes were treated with sera from 4 mares previously identified as zona posi...
Characteristics and fertility of stallion semen. A study of stallion fertility was conducted on commercial studs in eastern Australia over 4 breeding seasons (1974/75-1977/78). Data from 47 stallions (66 stallion seasons) aged 2-26 years and representing 7 breeds and 1664 mares were used to relate seminal characteristics to fertility. Percentage pregnancies per service was the most sensitive measure of fertility with stallions on commercial studs. Breed and age of stallion, breeding season and the referral status of the stallion ('suspect' or 'normal') had significant (P less than 0.01) effects on fertility. The semen characteristics that we...
Factors affecting testis weight in normal and cryptorchid horses. Testes were collected from normal and cryptorchid horses of a variety of breeds and ages and weighed after dissection from the epididymis. Scrotal testes grow little until the second winter of life and little thereafter, although a nearly mature body weight is reached by the end of the first winter. Scrotal testes in unilateral cryptorchids tend to be larger than those of normal stallions, sometimes exceedingly so, although occasional small scrotal testes are recorded. Inguinal testes show some tendency to grow during the second winter but the data are difficult to analyse beyond that age beca...
Pancreatic beta cell function in the neonatal foal. Plasma concentrations of insulin and glucose were measured in Pony and Thoroughbred foals at birth and at intervals thereafter for up to 7 days. The plasma concentrations of insulin in foals of both breeds at birth were 11.2 +/- 2.5 microU/ml (N = 6) and 13.5 +/- 1.5 microU/ml (N = 16) respectively. These values were similar to those obtained for foals in utero but were significantly less than those in adult animals. There was little variation in the plasma concentrations of insulin and glucose during the first 2 h of life and both concentrations tended to rise in the next 24-48 h. Although th...
Prevalence of antibodies to Legionella pneumophila in animal populations. We examined more than 2,800 human and animal sera for antibodies to four serogroups of Legionella pneumophila by using the microagglutination test. Antibody titers of greater than or equal to 1:64 were considered positive. The occurrence of positive equine sera (31.4%) was significantly higher than the occurrence of positive sera in cattle (5.1%), swine (2.9%), sheep (1.9%), dogs (1.9%), goats (0.5%), wildlife (0%), and humans (0.4%). The highest titer measured in horses was 1:512. The occurrence of positive sera in horses was related directly to age. In horses less than or equal to 1, 2 to 3,...
Equine onchocerciasis: lesions in the nuchal ligament of midwestern U.S. horses. Nuchal ligaments from midwestern U.S. horses infected with adult Onchocerca sp. were studied. The prevalence of Onchocerca sp. infection in horses increased with age. Ten percent of horses less than one year old were infected, 28% of horses one to five years old, 48% of horses six to 15 years old, and 90% of horses over 16 years old. Lesions in Onchocerca sp.-infected nuchal ligaments varied with age of the horse. Horses less than five years old had few or no lesions, whereas most horses six to 15 years old had focal mineralization and granuloma formation around adult worms. In infected nuchal...
[Structure and vascularization of the dental pulp in horse incisors]. The dental pulp of 34 horses aged between 4 months and 20 years has been studied on India ink injected and on paraffin embedded specimens. The pulp dimensions of the first and especially of the second dentition decrease with age. This reduction is accompanied by pronounced changes of structure; the mucous connective tissue becomes a dense, irregular connective tissue. The vessels are numerous and make a network particularly rich at the margins of the pulp; they diminish with advancing age. The reduction of the pulp volume and the regression of its vascular network are particularly pronounced a...
Blood volume and rate of growth in Standardbred foals. Blood volume and parameters of body size were studied in 45 Standardbred foals during their first 400 days of life. Bodily dimensions, including body weight (bwt), depth of chest, girth and length (distance from point of shoulder to caudal aspect of croup), increased curvilinearly with age. There was a much faster growth rate noted for the first 100 days of life. Bwt could be predicted from girth and length much more precisely than from age alone. The total blood volume increased proportionately with age and, consequently, the plasma and red cell volumes as functions of bwt were high at birth ...
Clinical, morphological and endocrinological aspects of cryptorchidism in the horse. The authors analysed clinical, histological and hormonal data obtained from 205 cryptorchid horses. The majority of the unilaterally and bilaterally retained testes were located in the inguinal canal; however, the ratio of inguinal vs abdominal retention appeared to decrease with advancing age. In unilateral cryptorchidism, a pronounced preference was noted for left abdominal retention, whereas for inguinal cryptorchids, the retained testes occurred equally on both sides. Right inguinal retention was found to decrease with advancing age. Histology of cryptorchid testes revealed apparently norm...
Serum thyroxine and triiodothyronine concentrations in neonatal foals and mature horses. Serum thyroxine (T-4) and triiodothyronine (T-3) concentrations were assayed in neonatal foals (1.5 to 4 months) and mature horses (2 to 25 years old) by a modified radioimmunoassay procedure. Blood was collected from 52 clinically healthy foals and horses of various breeds (Thoroughbreds, Quarter Horses, American Saddle Horses, and a single cross-bred horse). Neonatal foals had high serum concentrations of T-4 (mean, 4.02 microgram/dl) and T-3 (192.9 ng/dl) as compared with the values in mature horses (T-4, mean of 1.76 microgram/dl; T-3, mean of 98.69 ng/dl). Stallions had slightly higher T-...
Clinical trial of xylazine with ketamine in equine anaesthesia. One hundred anaesthetics were administered in a clinical trial to 95 equine patients, ranging in age from nine months to 19 years and in weight from 140 to 1270 kg, undergoing a variety of surgical procedures. Acepromazine maleate premedication (0.01 to 0.03 mg per kg intramuscularly) was given to seven animals, the remainder were not premedicated. Xylazine (1.1 mg per kg) was injected intravenously over a two minute period and after a pause of two minutes ketamine (2.2 mg per kg) was injected rapidly by the same route. For 30 procedures no other anaesthetic was given but in 59 cases anaesthes...