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Topic:Veterinary Medicine
Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
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.
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.
Embryological studies on the dartmoor pony during the first third of gestation. A sequence of ten known-age embryos recovered from Dartmoor Ponies during the first 4 months of gestation is described. Changes in size, shape and vascularity of the conceptus are recorded, as well as the growth and decline of the yolk-sac and the succeeding establishment of the allantochorion. The progress of equine somatogenesis is compared with that of the pig which it lags on average of about 4 days. Some quantitative data are presented.
Carbonic anhydrase isozymes in American ponies and riding horses: a new polymorphic high-activity type isozyme. A study of the erythrocyte carbonic anhydrases of 219 American ponies and 76 riding horses has revealed the presence of five variants of the low-activity CA B isozyme and two variants of the high-activity CA C isozyme. The previously undetected variant of CA C was found only in the pony population and had an allele frequency of 8.9%. A family study of animals possessing the CA B variant A2 showed an unexpected high frequency of inheritance.
Preliminary observations on cranial cardiovascular changes during asphyxia in the newborn foal. This paper describes preliminary experiments designed to test the hypothesis that cerebral damage is caused by cardiovascular events involving explosive changes in cerebral blood flow during birth. These events may be responsible for the convulsive episodes of foals suffering from the neonatal maladjustment syndrome.
Ovarian changes during early pregnancy in pony mares in relation to PMSG production. The ovaries of twenty pregnant mares were examined daily, per rectum, for the first 4 months of gestation and note was made of their estimated size and follicular content. Serial blood samples from sixteen of the mares were assayed for PMSG. A marked seasonal effect was noted on ovarian size, follicular content and ovulation rate during pregnancy but there was no such effect on PMSG production. It is concluded that PMSG is synergistic with gonadotrophins of pituitary origin and that the latter hormone are the primary stimulus on the ovary of the pregnant horse.
Characteristics of the successive jets of ejaculated semen of stallions. The use of an 'open' artificial vagina made it possible to separate the individual jets in the ejaculate of the stallion. A total of 132 jets were collected in this way from twenty-one ejaculates. After macro- and microscopic examination and sperm counting, glycerylphosphorylcholine (GPC), ergothioneine and fructose levels were determined for every jet. The values obtained for the first three jets were similar and accounted for about 76% of all spermatozoa, and 70% of GPC. These jets also contained the highest concentration of ergothioneine and fructose.
The use of intravascular catheters for long-term studies on the mare and fetus. Methods developed for the insertion of catheters into the umbilical artery and vein and the uterine vein of the pregnancy mare are described. The technique requires careful anaesthesia and the maintenance of normal blood gas tensions, pH and arterial blood pressure. Fetal survival was variable: three mares delivered live foals and six fetuses survived more than 15 days with a maximal period of 41 days. The erythrocytes sedimentation rate (ESR) of the fetal foal was always very low at operation but subsequently increased slightly; a sudden large rise in ESR usually indicated imminent fetal deat...
The distribution of delta5-3beta-hydroxysteroid dehydrogenase in the graafian follicle of the mare. Graafian follicles of various sizes obtained from mares at different stages of the oestrous cycle were examined histologically and histochemically for delta5-3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity and related enzymes. The 3beta-HSD activity was not found in the theca interna of any follicles but was present in the membrana granulosa of well-vascularized large follicles in the late luteal phase of the cycle and at oestrus. These findings indicate that pregnenolone cannot be converted into progesterone in the theca interna. It is suggested that this conversion occurs in the memb...
The use of prostaglandin F2alpha in controlling the oestrous cycle of the mare and steroid changes in the peripheral blood. Prostaglandin F2alpha (PGF2alpha), administered by untrauterine infusion and intramuscular injection, was used to induce oestrus and ovulation in non-cyclic mares. A satisfactory response rate (80% or more) was obtained and the dose (2-5--7-5 mg) and the time taken for ovulation to occur (up to 9 days) was the same irrespective of the route of administration. Only about one-half of the mares conceived to mating at the induced oestrus but the low conception rate could be attributed to the infertile condition of the mares. Plasma progesterone remained at basal levels after PGF2alpha and oestroge...
Cardiopulmonary effects of positive end-expiratory pressure in anesthetized horses. The cardiopulmonary effects of 0, 5, 10, and 15 cm of H2O positive end-expiratory pressures (PEEP) were determined in anesthetized, spontaneously breathing horses, using a 4 by 4 Latin-square design with one repetition. Cardiac output, alveolar-arterial oxygen tension difference, alveolar ventilation, dead space/tidal volume ratio, and carbon dioxide elimination were not significantly altered by the procedure. As PEEP was increased, alveolar and arterial oxygen tensions, respiratory exchange ratio, and pH decreased, whereas arterial carbon dioxide tension and oxygen consumption increased. Thes...
A study of the morphology of stallion semen during the breeding and non-breeding seasons. Season was shown to markedly influence semen characteristics of stallions in Holland, including ejaculate volume, sperm motility, total number of spermatozoa/ejaculate and the percentage of spermatozoa showing morphological abnormalities. Maintenance of normal stallions in continuous light during the winter months and administration of a vitamin and mineral supplement to sub-fertile stallions before the start of the breeding season appeared to improve spermatogenesis significantly.
A preliminary report on regenerative healing in the equine tendon. The concept of regenerative healing has been used to manipulate the healing process in experimental animals and clinically to augment bone healing in people after orthopedic operation. An implanted electrical device was used in an attempt to produce regenerative healing in experimentally created equine tendon injury. The bimetallic electrical implant did not produce regenerative healing under the conditions of this experiment. The mechanism of implantation and discussion of the results are included.
Plasma progestagens in cyclic, pregnant and post-partum mares. The pattern of plasma progestagen levels during the oestrous cycle was similar to that previously reported except for lower peak levels. The lack of significant difference (p less than 0-01) between CPBA and RIA values suggests that progesterone itself is the major component during the oestrous cycle. Progesterone levels during the first and second post-parturient oestrous cycles were similar to those observed during the cycle of the non-pregnant mare. During pregnancy there were two peaks of plasma progestagens. The first, which occurred during the 3rd month, coincided with high levels of PMS...
Control of microflora in stallion semen with a semen extender. Sterile equipment was used to collect ten ejaculates from each of ten normal stallions and quantitative and qualitative bacterial counts were made within 15 min after collection. The mean bacterial population in undiluted semen was found to be 573,000 +/- 374,000 organisms/ml. The bacterial content of semen diluted with two parts sterile physiological saline, or with two parts of a cream-gelatin extender, was measured within 15 min after collection and again after 2 hr at 25 degrees C. The number of bacteria was slightly increased in the saline after 2 hr, but 1 93% and 99% reduction occurred ...
Cerebrospinal fluid alkalosis during high-altitude sojourn in unanesthetized ponies. Unanesthetized adult female ponies were studied near sea level (250 m) and during sojourns to 3400 m (N=6) and 4300 m (N=7) altitude. The pH, PCO2, and PO2 of arterial blood and pH and PCO2 of cerebrospinal fluid (CSF) were measured under conditions of acute (1 hr) and chronic (1-45 days) hypoxia. Cerebrospinal fluid was sampled from the cisterna magna of the awake pony and arterial blood withdrawn from an indwelling arterial catheter. In both groups of animals, PaCO2 decreased slightly after 1 hr of hypoxia (delta PaCO2= - 0.6 mm Hg at 3400 m; - 3.9 mm Hg at 4300 m), decreased further after 1...
Serum concentrations of FSH, LH and progesterone during the oestrous cycle and early pregnancy in the mare. Heterologous radioimmunoassays were developed for equine FSH and LH. Serum concentrations were measured in twenty-three mares throughout the oestrous cycle and early pregnancy. FSH concentrations were raised fivefold by 'surges' rather than 'spiked', occurring at 10- to 11-day intervals during the oestrous cycle and early pregnancy. The late oestrous/early dioestrous surge of FSH appeared to initiate development of up to twenty follicles. The mid-dioestrous surge may be important for the further development of follicles destined to ovulate 10 to 13 days later. Levels of LH were increasing by t...
Control of fertility in Thoroughbred horses in West Germany. A central control system for German Thoroughbred horses is described. Autumn examination of mares and stallions enables them to be classified according to breeding potential. The results of 25 years of study are reported.
Effect of exogenous progesterone on its endogenous levels: biological half-life of progesterone and lack of progesterone binding in mares. The disappearance rate of progesterone from blood plasma of an ovariectomized mare was rapid and occurred in three phases. The half-life of the first component was 2-5 min and that of the second was 20 min; the half-life of the much slower third component was not measured. Progesterone, administered to ovariectomized and deeply anoestrous mares at the rate of 150 or 300 mg/day, maintained maximal peripheral levels of 6 to 8 ng/ml. Physiological levels were reached in 21 days using a dose of 150 mg and in 11 days with 300 mg daily. After withdrawal, circulating levels dropped rapidly. Blood pla...
