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Topic:Equine Health
Equine health encompasses the study and management of diseases, disorders, and overall well-being of horses. It involves understanding various physiological systems, preventive care, and treatment strategies to maintain optimal health in equine populations. Common areas of focus include nutrition, infectious diseases, orthopedic conditions, and reproductive health. Research in equine health aims to advance knowledge on diagnostic methods, therapeutic interventions, and management practices that improve horse welfare and performance. This page collects peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine health, offering insights into current findings and advancements in the field.
Cytogenetic studies of three equine hybrids. A detailed investigation of testicular meiosis in a mule, a hinny and a Przewalski horse/domestic horse hybrid were made. Abnormalities of pairing were observed in the mule and hinny in most germ cells at the pachytene stage of meiotic prophase, and spermatogenesis was alsmot totally arrested. A few mature spermatozoa were recovered from the ejaculate and epididymal flushings of the hinny. The Przewalski horse/domestic horse hybrid was fertile and showed normal spermatogenesis. Chromosome banding studies showed a close homology between the karyotypes of the Prezwalski horse (Equus przewalskii,...
Studies on mild composition and lactogenic hormones in the mare. Small samples of mammary secretion were collected from eight Thoroughbred mares during the last week of pregnancy, at foaling and after 1 week of lactation. Specific assays showed the presence of both lactose and triglyceride in all samples before birth and progressive increases in their concentrations in colostrum and in milk. Levels of 6-0 g lactose/100 ml and 1-8 g triglyceride/100 ml were present in milk at 7 to 9 days post partum. The secretory capacity of the udder is thus normally established well before parturition in the mare. Attempts to demonstrate the occurrence of a placental lact...
Ontogeny of equine haemoglobins. Studies were made of the O2 affinities of fetal and maternal haemoglobins in the horse, and correlations were found with erythrocytic levels of 2,3-diphosphoglycerate.
Experimental studies on equine herpesvirus type 1 infections. The EHV-1 viruses of fetal origin grew better and had a wider tissue culture host range than those isolated from horses with respiratory diseases. Comparisons of a fetal isolate (F/304) and a respiratory disease isolate (R/NM-3) in partly immune horses showed that the F/304 virus infected horses more readily, grew better in the nasopharynx, was more likely to cause abortion, and was excreted to a greater extent into the environment.
A surgical technique applied to the study of tubal eggs in the mare. An efficient surgical technique of collecting eggs from the oviducts of mares is described. Within 6 days after ovulation recovery was successful in 22/29 mares. The technique has been used to investigate the retention and ageing of eggs in the oviducts and to determine the origin and the nature of the accessory CL during pregnancy.
The gnotobiotic foal in the study of infectious diseases. A method of rearing germ-free gnotobiotic foals is described. To date, four foals have been infected with rhinopneumonitis and the only clinical signs of infection have been a transient fever and leukopaenia; no detailed results are, as yet, available.
Surgical and non-surgical egg transfer in horses. Surgical and non-surgical methods used for the recovery and transfer of fertilized horse eggs are described. Sixteen of the twenty-three zygotes recovered surgically between Days 1 to 6 after ovulation from thirty donor mares were transferred surgically to synchronized recipients; seven pregnancies resulted. Seven of the eleven zygotes recovered non-surgically between Days 6 to 8 after ovulation from twenty-eight donor mares were transferred non-surgically to synchronized recipients; five pregnancies resulted.
Comparison of the methods of rectal palpation and haemagglutination-inhibition assay for diagnosis of pregnancy in mares. The diagnostic value of rectal palpation and immunological assay of PMSG was tested at different stages of pregnancy in mares inseminated with frozen semen in three separate studies. The results were based on foaling success and particular attention was paid to the numbers of inconsistent results obtained by the two tests. Generally, the number of false positive diagnoses was lower for the immunological assay than for palpation in early pregnancy (Days 40 to 60) and the relationship became reversed later in gestation.
Abnormalities of mating behaviour in domestic stallions. Experimental and clinical observations were made to treat abnormal sexual behaviour. The most common cause of abnormality was mismanagement of the animal; over-use and rough treatment at service and too-frequent ejaculation during winter had a detrimental effect on the behaviour of young stallions. Pain due to injury incurred at copulation or when associated with mounting attempts was also a common cause of impotence. Most impotent stallions responded well to re-training and recovery can be achieved without pharmacological treatment in most cases.
Effect of season on some characteristics of stallion semen. Season had a pronounced effect upon seminal pH and refractometer 'protein', total carbohydrate, dry weight, total N2 and lactic acid in seminal plasma of first and second ejaculates. In addition, total seminal volume, spermatozoa per ml and per ejaculate, non-protein sulphhydryl and glycerylphosphorylcholine of second ejaculates were also influenced. There was a season difference in the concentrations of lactic acid in spermatozoa from first and in total N2 from spermatozoa in second ejaculates. The effects of season on seminal plasma were greater than those on spermatozoa. Spermatozoa in firs...
Effects of artificial light on the oestrous cycle of the mare. Two groups, each of seven pony mares, were maintained from 17 October to 15 February (120 days) in the University Biotron where temperature and daily photoperiod were regulated to simulate normal conditions for that period (control group) or those normally applicable from 1 March to 1 July (treated group). Follicular growth, ovulation rate and oestrous behaviour were determined daily by rectal palpation, and by teasing with a stallion. By Day 69 of treatment, all ovarian end-points (number of follicles greater than 10 mm, number of follicles greater than 20 mm, average follicle diameter and di...
Patterns of urinary oestrogen excretion in individual pregnant mares. Urine collections (24 hr) were made at weekly intervals from four Pony mares from the 3rd or 4th month of pregnancy until parturition. Separation of oestrogens on Celite columns was followed by Kober measurements of oestrone and equilin. Individual differences were noted in peak amounts of total oestrogens excreted (200 to 800 mg/day), when oestrone constituted 80 to 95% at the 6th to 7th months. Although equilin increased in later gestation, oestrone remained the major product. Total oestrogen values decreased rapidly from the peak and then more gradually towards the end of pregnancy. During ...
Chromosome abnormalities as a cause of infertility in mares. Chromosomal abnormalities have been detected in seven mares isolated by their poor reproductive performance. All had small or rudimentary gonads and absent or irregular oestrous cycles. Two mares had an XO genotype, one was a 65,XXX female and another a 64,XY sex-reversed female. Two other mares were sex chromosome mosaics of the 63,X/64,XX type. The seventh mare showed a normal female karyotype but a small extra autosomal fragment was found in a few cells.
Transfer of gases and metabolites in the equine placenta: a comparison with other species. Mares and fetuses with indwelling catheters in the umbilical and uterine vessels have been used to monitor transplacental blood gas tensions, pH, O2 affinities and the concentration of various metabolites in fetal and maternal blood during late gestation. Measurements of umbilical and uterine blood flows and arterio-venous differences enabled the uptake of O2 and glucose by the fetus and the uterus to be estimated. The present findings are compared with those from other species in comparable conditions.
Oestrone and equilin in the plasma of the pregnant mare. A method for the extraction of oestrone and equilin from the plasma of the pregnant mare is described, and the levels obtained for eighty-two samples from fourteen Welsh Mountain Ponies at different stages of pregnancy are recorded. Oestrone (fifteen samples) and equilin (three samples) were not found before Day 120. From Day 120 to 240, oestrone levels exceeded 100 ng/ml and then declined to parturition. The high concentrations of oestrone in mid-pregnancy were associated with gradually increasing concentrations of equilin which tended to plateau after Day 180 at just under 100 ng/ml and decl...
Effects of prostaglandin F2alpha on the oestrous cycle and pregnancy in mares. Several experiments indicated that prostaglandin F2alpha (PGF2alpha) has luteolytic and abortifacient properties in mares. A single subcutaneous injection of 1-25 mg PGF2alpha on Day 6 of dioestrus was as effective as 10 mg PGF2alpha in inducing luteolysis. Oestrus and ovulation appeared to be synchronized when a single injection of 1-25 mg PGF2alpha was given on Days 7, 10 or 13 after ovulation but not on Days 1 or 4 after ovulation or on Day 2 of oestrus. Intramuscular administration was as effective as subcutaneous administration and 1-25 mg PGF2alpha was the minimal effective systemic dose...
Recent observations concerning Klebsiella infections in stallions. A high incidence of Klebsiella contamination in German 'Warmblut' and Thoroughbred stallions is reported. The organism was recovered from the nostrils, prepuce, pre-ejacultory secretion and, in some cases, on the body surface, in the faeces and on the ground of the covering (mating) yard. Fertility was not affected. However, differences of virulence were observed and Type 5 proved to be the most pathogenic.
Oestrogen excretion in mares in relation to various reproductive states. The rate of urinary oestrogen excretion was studied in four ovariectomized mares. In two animals ovariectomized when urinary oestrogen concentration was high, levels fell to a minimun within 48 hr. Intramuscular injection of oestradiol-17beta produced maximum urinary oestrogen levels within 3 to 6 hr and a return to minimum detectable levels within 24 hr. The major urinary oestrogen in mares was oestrone. In nine maiden mares studied between September and June, the cycle, the durations of dioestrus and oestrus, and the time of ovulation were similar in autumn (September to December) and spring...
Androgens and oestrogens in normal and cryptorchid stallions. Total androgens, testosterone and total oestrogens were measured in twenty-one intact, nine unilaterally cryptorchid, three bilaterally cryptorchid stallions and four geldings. Total oestrogens were significantly higher (P less than 0-005) and total androgens significantly lower (P less than 0-05) in the bilateral cryptorchid compared to other groups. There was a significant (P less than 0-025) day and night variation in total androgen levels. Thyroidectomized and intact animals showed a marked decrease in total androgen as well as testosterone levels during the winter period thus showing an e...
Fine structure of the gonads of the horse and its functional implications. Light and electron microscopic studies of the gonads of the fetal horse have shown that, in their hypertrophic condition which begins during the 3rd month, the interstitial cells contain large amounts of smooth endoplasmic reticulum, suggesting a secretory activity. Hydroxylating activity which was cytochrome P-450-dependent was observed in the fetal testis and may be involved in steroid biosynthesis.
Clinical management of equine ovarian neoplasms. The rarity of equine ovarian neoplasms is attested to by the lack of reports in the literature. However, sixteen cases have been diagnosed at the Iowa State University Veterinary Hospital in the last 3 years and, of these, the granulosa-cell tumour was the most common. A study of the clinical and subsequent histories of these and other mares reveals some common findings as to age, breed, reproductive status, clinical signs, and post-surgical reproductive capability.
Development of the equine fetus and placenta. Prenatal specimens from mares with known breeding dates were used to characterize morphological changes in the fetus and placenta of pony mares. Prenatal characteristics and the day on which each was first found and weights of different components of the equine conceptus are summarized.
The development of the lung and its surfactant in the foal and in other species. The development of the lung from the glandular through the canalicular to the alveolar stages in the horse fetus is described. Traces of surfactant and occasional lamellated osmiophilic bodies representing intracellular surfactant were found at 150 days of gestation, some 40 to 60 days before the transition to the canalicular stage. During this transition some of the cuboidal cells of the glandular rosettes are transformed into cells of Types I and II, but the surfactant is not fully developed until 300 days or, in some foals, until after delivery.
Sperm transport and distribution in the mare. Fifty mares were inseminated on Days 2, 4, 7, 11 or 17 of the oestrous cycle with spermatozoa from one of three stallions to observe the distribution of the spermatozoa in various parts of the reproductive tract 12 hr later (Days 3, 5, 8, 12 and 18). Only 0-06 to 2-21% of inseminated spermatozoa were recovered from the tract. More (P less than 0-05) spermatozoa were recovered from the cervix and uterus on Day 12 than on Days 3, 5, 8 and 18. The mean number of spermatozoa recovered from either or both oviducts was significantly greater (P less than 0-10) on Days 5 and 8 than on Days 3, 12 and 1...
Candida infection of the genital tract in thoroughbred mares. This paper describes sixteen cases of Candida infection of the genital tract in Thoroughbred mares. Clinical signs and histopathological lesions of the disease are described and the results of treatment with Lugol's solution and Nystatin are given.
Origin and histogenesis of equine endometrial cups. Biochemical and morphological studies were carried out to determine the origin and histogenesis of endometrial cups in mares. A wide range of fetal and maternal tissues were cultured in vitro and their ability to secrete gonadotrophin (PMSG) was monitored. High levels of PMSG were produced in culture only by cells from the restricted area of the equine trophoblast known as the chorionic girdle which is an annular band of highly specialized cells at the junction of the allantois and the regressing yolk sac. The morphological appearance of girdle cells after cultivation in vitro and after alloge...
Immunoglobulins produced by the antigenized equine fetus. The foal is born without detectable antibody and except for small amounts of IgM is devoid of immunoglobulins. Intrafetal administration of either Venezuelan equine encephalomyelitis virus (VEE-TC83) or ovine erythrocytes elicited IgGa, IgGb and a trace of IgG(T). The fetal blood VEE-TC83 neutralization titre was higher than the neutralization titre elicited by the same preparation in older horses.
