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Topic:Horses
"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Treatment of respiratory distress in a prematurely born foal. A foal born 3 weeks prematurely was treated for respiratory distress, using a combination of oxygen therapy and mechanical ventilatory assistance. Clinical response and arterial blood gas tensions were monitored regularly. Continuous positive-airway pressure and intermittent positive-pressure ventilation administered via a nasotracheal tube were effective in improving arterial oxygenation and ventilatory function.
The hypersensitivity of horses to culicoides bites in british columbia. Culicoides hypersensitivity is a chronic, recurrent, seasonal dermatitis of horses that has a worldwide distribution, but has only recently been reported in Canada. It is characterized by intense pruritus resulting in lesions associated with self-induced trauma.A survey of veterinarians and horse-owners in British Columbia showed no differences in susceptibility due to the sex, color, breed, or height of the horses. The prevalence of the disease in the 209 horses surveyed was 26%. Horses sharing the same pasture could be unaffected. The disease was reported primarily from southwestern British ...
Experimental chemotherapy in horses infected with benzimidazole-resistant small strongyles. The presence of benzimidazole-resistant strains of equine small strongyles was confirmed in horses at two properties in north west England by a series of faecal egg counts and larval cultures after treatment with mebendazole. A trail formulation of mebendazole in combination with piperazine citrate gave greater reductions in faecal egg counts than mebendazole alone but was much less effective than pyrantel embonate or dichlorvos.
Cytochrome c: ion binding and redox properties. Studies on ferri and ferro forms of horse, bovine, and tuna cytochrome c. The ion binding properties of horse, bovine, and tuna cytochrome c (both oxidized and reduced) have been measured using a combination of ultrafiltration, neutron activation, and ion chromatography. The ions investigated were chloride, phosphate, and Tris-cacodylate. Ion chromatography and neutron activation analysis techniques were employed to determine the concentration of free anions. Binding constants are obtained from modified Scatchard plots (in the range of 10-2000 M-1). The redox potentials for cytochrome c at different ionic strengths, pH 7.0, have been determined. In this paper we rep...
Pre-chemotactic and chemotactic properties of uterine fluid from mares with experimentally induced endometritis. Streptococcal endometritis was induced experimentally in pony mares during oestrus. Uterine fluid was collected 30, 60, 120 or 240 minutes later and tested for its effect on the in vitro morphology and chemotaxis of equine neutrophils by two independent methods. The maximal response occurred between 30 and 60 minutes after infection and persisted until 240 minutes. The chemo-attractant contained both heat labile and heat stable components and the latter appeared to be active at low concentrations.
Small intestinal obstruction associated with wood chewing in two horses. Although wood chewing by horses is recognised as a common vice, there are few reports of specific disease associated with the habit. Two cases of acute obstruction of the small intestine by solid aggregations of wood splinters are described in horses which were both habitual wood chewers. Details are presented of the clinical findings in these cases, including the surgical treatment of acute colic. Both horses returned to full working fitness. The authors review the syndrome of enterolithiasis in horses, and discuss the causes and significance of wood chewing as a stable vice.
Molecular mechanics calculation of geometries of NAD+ derivatives, modified in the nicotinamide group, in a ternary complex with horse liver alcohol dehydrogenase. The geometry of seven NAD+ analogues bound to horse liver alcohol dehydrogenase (LADH) modified only in their nicotinamide group, have been studied using AMBER molecular mechanics energy-minimization procedures. Starting geometries were taken from X-ray crystallographic data for NAD+/Me2SO/LADH reported by Eklund and co-workers. In this study the NAD+ analogues were encaged by the constituent amino acids of the enzyme within a range of 0.6 nm from the initial NAD+/Me2SO/Zn2+ complex. The calculational method used is able to rationalize individual substituent effects and to evaluate the essenti...
Primary malignant pulmonary neoplasia in two horses. Although primary malignant pulmonary neoplasia of horses is rarely encountered, this diagnosis was confirmed in 2 horses on the basis of necropsy and histopathologic findings. One horse, with cystic mucinous adenocarcinoma, had respiratory tract and neurologic signs directly attributable to the neoplasm, and a tentative antemortem diagnosis of pulmonary neoplasia was made. The other horse, with anaplastic bronchogenic carcinoma, did not have clinical signs of pulmonary neoplasia.
Esophageal duplication cyst as a cause of choke in the horse. A mare was examined for episodic choking and an abscess in the perilaryngeal region. One month before referral, the mass progressively enlarged, causing esophageal choking. An extraluminal compression of the esophagus 90 cm from the external nares was found on endoscopy and contrast radiography. Serosanguinous fluid aspirated from the mass contained keratinized squamous cells and neutrophils, compatible with an esophageal cyst. Surgical exploration was performed, with incomplete surgical excision. The remaining portion of the cyst was marsupialized and treated locally with a 2% inorganic iodin...
Horse brain acylphosphatase: purification and characterization. Two structurally different acylphosphatases found in horse brain were purified; they were not immunologically related. The molecular masses were almost identical and the kinetic parameters were rather similar. The data reported indicate that one of the purified brain acylphosphatases and an enzyme, previously isolated from horse muscle, are the same protein. The presence of this acylphosphatase form in the brain has not been reported before. The other acylphosphatase seemed to be the same as the enzyme which had been purified from calf brain and partially characterized by Diederich and Grisoli...
Differences in diagnostic test results and hematologic data between aged and young horses. Hematologic data and results of diagnostic tests were compared between aged (greater than or equal to 20 years old) and young (less than or equal to 5 years old) horses to identify hematologic and metabolic changes associated with aging. Initial data were obtained from 8 aged and 6 young mares (group 1). Similar data were collected from a second group of aged (3 mares and 3 geldings) and young (1 mare and 5 geldings) horses (group 2). Dexamethasone suppression tests (DST) and necropsies were performed on 6 additional mares and mare 8 from group 1 (group 3). Complete blood counts and serum bioc...
Trauma and the veterinarian. A survey of all American Veterinary Medical Association members in Minnesota and Wisconsin was conducted by questionnaire to document injuries resulting from animal treatment. Of 995 respondents, 64.6% had sustained a major animal-related injury. Seventeen per cent were hospitalized within the last year. Of those hospitalized, 25.3% required a surgical procedure. Hand injuries were most common in a veterinarian's career (52.6% of respondents), followed by trauma to the arms (27.6%), and the head (20.8%). The thorax (8.3%), genitalia (3.9%), and intra-abdominal viscera (2.8%) were injured less ...
Nonsurgical treatment of uterine torsion in seven mares. Nonsurgical correction of uterine torsion was performed in 7 mares, and 6 foals were subsequently born alive. Uterine rupture necessitated euthanasia in 1 mare. Correction was achieved by rolling of the mares after general anesthesia had been induced. Previously, this technique was believed to be associated with a high prevalence of fetal and maternal mortality. Nonsurgical correction may be a satisfactory alternative to abdominal surgery in treating uterine torsion in mares.
African horse sickness in Zimbabwe: 1972 to 1981. During the nine years from October 1972 to September 1981 African horse sickness (AHS) virus was isolated from 23 suspected cases of the disease in Zimbabwe and complement fixation antibody titres indicative of recent infection were detected in a further 49 horses. The 23 isolations belonged to seven of the nine known serotypes of AHS virus. In response to a questionnaire in 1980 the owners of 20% (1,654/8,000) of the horses in Zimbabwe indicated that they had recorded 207 cases of clinically diagnosed AHS with 107 deaths from 1975 to 1980. Fifty-six cases with 50 deaths had occurred in foals ...
Effects of an abrupt diet change from hay to concentrate on microbial numbers and physical environment in the cecum of the pony. Microbial numbers, pH, fluid volume, and turnover rate in the pony cecum were measured during an abrupt change from an all-forage to an all-concentrate diet, both fed at maintenance energy levels. Concentrate feeding resulted in increased (P less than 0.01) numbers of total viable anaerobic bacteria. The numbers of organisms growing on selective starch medium increased (P less than 0.01) when concentrate was fed, while numbers on xylan and pectin media decreased (P less than 0.025). Seven days after the diet change to concentrate, the number of bacteria growing on lactate medium increased (P l...
Endometrial biopsy of the mare. A review and update. The endometrial biopsy is a safe and effective means of predicting a mare's prognosis for foaling. A thorough understanding of the normal cyclic and seasonal pattern displayed by the normal endometrium is necessary before interpreting pathologic changes. Several systems for prognostic classification have been proposed, including a recent one that combines many of the criteria used in the other systems.
Immune responses are required to terminate viremia in equine infectious anemia lentivirus infection. Six normal and four immunodeficient horses were injected with a cloned variant of equine infectious anemia virus (EIAV). The six normal horses had detectable EIAV in their plasma by 7 days postinjection. During their primary viremic episode, which was accompanied by fever and anemia, maximum titers of EIAV in plasma ranged from 10(3.8) to 10(4.8) 50% tissue culture infective doses per ml. All six normal horses cleared detectable virus from their plasma by 21 to 35 days after injection. Horses with combined immunodeficiency became viremic by 9 days postinjection and also developed anemia. In co...
Brain cholinesterase activity in animals and birds. Normal cholinesterase activity in brain tissue was measured in various mammalian and avain species. The cholinesterase activity in the cerebrum of cattle, swine, sheep and horses was approximately 2-3 umoles/min/g of tissue in each instance. The whole brain cholinesterase activity of small feral mammals was approximately 2 to 5 fold greater than the domestic animals. Considerable interspecies variability was present in the feral mammals. Similar variability was also observed in the avian brain cholinesterase determinations. The avian whole brain cholinesterase activities ranged from 9.78 to 21...
Embryonic loss in mares. Incidence, possible causes, and diagnostic considerations. Fertilization rates were similar for normal and subfertile mares, and much of the difference in fertility between normal and subfertile mares was due to embryonic loss. Fertilization rate estimates for mares ranged from 71 to 96 per cent. The incidence of embryonic loss detected by ultrasonography between Days 11 and 50 was approximately 9 per cent for normal mares, and the estimated incidence of embryonic loss before Day 14 was also 9 per cent. Therefore, the estimated incidence of embryonic loss in normal mares between fertilization and Day 50 is approximately 18 per cent (Fig. 1). In subfer...
XY sex reversal syndrome in the mare: clinical and behavioral studies, H-Y phenotype. An inherited genetic disorder causes XY embryos of the horse to develop as mares. On the basis of our study of 38 such mares, we have identified four grades or classes of XY sex reversal according to this scheme: class I, nearly normal female, of which some are fertile; class II, female with gonadal dysgenesis, normal mullerian development; class III, intersex mare with gonadal dysgenesis, abnormal mullerian development, enlarged clitoris; class IV, virilized intersex characterized by high levels of testosterone. In general, class I and class II mares were typed H-Y antigen-negative whereas cl...
Control of the estrous cycle in the mare. All current approaches to manipulating the reproductive biology of the nonpregnant mare are discussed.
Diagnosis and correction of twin pregnancy in the mare. Reproductive Physiology 1. Twin pregnancies result in high rates of abortion, stillbirth, and neonatal mortality. 2. Twins develop subsequent to multiple ovulations. Multiple ovulations are related to breed, parity, and mare history. Multiple ovulations are most frequently seen in Thoroughbred and Draft mares. Multiple ovulations are more common in barren and perhaps maiden mares than in lactating mares, and they are more common in certain individual mares. 3. Equine embryos are motile in the uterus from the time of first detection (Days 9 to 10) until fixation (Day 16). They are frequently lo...
Ultrasonic imaging of equine ovarian follicles and corpora lutea. One of the most profound theriogenology applications of transrectal diagnostic ultrasonography in mares involves the imaging of ovarian follicles and corpora lutea. The resolving capabilities (frequency) and quality of the scanner directly affect the minimal size of a structure that can be imaged and the quality of the image. High-frequency scanners (5 or 7.5 MHz) of good quality can image a 2-mm follicle and the corpus luteum throughout its functional life. A low-frequency scanner (3 or 3.5 MHz) can image a 6-mm follicle and the corpus luteum for several days after ovulation. Equine follicles...
Metabolism of naturally occurring [13C]glucose given orally to horses. In 5 horses, 13CO2/12CO2 ratios in expired air were determined using isotope mass spectroscopy to investigate metabolism of naturally occurring [13C]glucose. Oral glucose tolerance tests (OGTT) were performed using maize or beet glucose. Maize has a higher 13C concentration than that of most plants. The 13CO2/12CO2 ratios after OGTT was performed using maize glucose were compared with 13CO2/12CO2 ratios in expired air after OGTT was performed using beet glucose. The ratio also was determined during the period horses were not fed. Using OGTT, all horses were glucose tolerant. The OGTT performed...
Slab fractures of the third carpal bone in standardbreds and thoroughbreds: 155 cases (1977-1984). Case records and radiographs of 155 horses with third carpal bone (C3) slab fractures were reviewed. Of these cases, race records were obtained for 72 Thoroughbreds and 61 Standardbreds. Three performance criteria were examined: ability to make 1 start, ability to make 10 starts or earn $2,000 (within 1 year of first start after the fracture), and earnings per start. Treatment distribution (lag screw fixation, fragment excision, or rest) was similar in both breeds. Significant differences between breeds were identified in age and sex distributions, fracture displacement, and postinjury perform...
Alpha 1-adrenergic-induced airway obstruction in ponies with recurrent pulmonary disease. We examined the response of five ponies with recurrent airway obstruction (principals) and five age- and gender-matched controls to the aerosol alpha-adrenergic agonist phenylephrine after blockade with propranolol and atropine. Measurements were made with principal ponies in clinical remission (period A) and during acute airway obstruction (period B). The blockade had no effect on base-line pulmonary mechanics in control ponies during periods A and B or in the principal ponies during period A. However, in the principal ponies during period B, blockade increased dynamic compliance (Cdyn) and d...
Acute phase response in the horse: plasma protein changes associated with adjuvant induced inflammation. The induction of an acute phase response in four horses by adjuvant administration was used to examine the effect on the levels of plasma proteins. Blood parameters (packed cell volume, total plasma protein, red blood cell count, haemoglobin concentration) were monitored to follow the progress of the acute phase response in parallel with the examination of plasma proteins. Plasma protein levels were determined by densitometry from the electrophoretic patterns of three different gel systems. Haptoglobin and alpha 1 B glycoprotein were shown to be positive acute phase reactants whereas albumin w...
Effects of frequency and airway pressure on gas exchange during interrupted high-frequency, positive-pressure ventilation in ponies. Cardiovascular effects and pulmonary gas exchange were compared during conventional mechanical ventilation (CMV) and interrupted high-frequency, positive-pressure ventilation (IHFPPV) in 6 anesthetized ponies in dorsal recumbency. When the peak airway pressure (Paw) was held constant at control values attained during CMV (18 to 20 cm of H2O), and the ventilator frequency of IHFPPV was varied over the range, 2.5 to 12.5 Hz, significant (P less than 0.05) changes from control values were observed only in the ratio of dead-space volume to tidal volume (VD/VT) and in the respiratory minute volume ...
An inherited connective tissue disease in the horse. The hyperextensible, fragile skin of two related horses was compared with the skin of eight normal horses. Skin sections were examined by light microscopy and transmission electron microscopy. The deep dermal layer of the dorsal abdomen was much thinner in the affected horses, and contained bundles of collagen fibers which were more loosely packed. Within individual fibers, the fibrils were frequently curved and nonparallel rather than straight and parallel. Both of the affected animals had a greater range of fibril diameters than a normal horse. They had some unusually thick fibrils with very...
Reproductive physiology of the nonpregnant mare. An overview and update. This article reviews the reproductive events in the nonpregnant mare with emphasis on recent advances. The discussion is restricted to the salient features of puberty (prenatal and prepubertal events), seasonality (gonadotropins, photoperiod, and other modifying factors), and the estrous cycle (hormones, estrus, diestrus, and the control of cyclicity) in the nonpregnant mare.
