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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.
Relationships among LH, FSH and prolactin secretion, storage and response to secretagogue and hypothalamic GnRH content in ovariectomized pony mares administered testosterone, dihydrotestosterone, estradiol, progesterone, dexamethasone or follicular fluid. Thirty-five ovariectomized pony mares were used to study the relationships among luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) concentrations in blood (secretion), in pituitary (storage) and in blood after secretagogue administration, as well as the content of gonadotropin releasing hormone (GnRH) in hypothalamic areas, under various conditions of steroidal and nonsteroidal treatment. Five mares each were treated daily for 21 d with vegetable shortening (controls), testosterone (T; 150 micrograms/kg of body weight, BW), dihydrotestosterone (DHT; 150 microgram...
In vitro transport of cycloleucine by equine cecal mucosa. Mucosa obtained from the cecum of healthy horses and incubated in vitro with 0.1 mM cycloleucine could accumulate this amino acid against an apparent concentration gradient after 60 and 120 minutes. Accumulation by the serosal (antiluminal) surface of the tissue was 3 times greater than accumulation by the mucosal (luminal) surface after 120 minutes (P less than 0.001). Cycloleucine accumulation was significantly reduced by Na deprivation after 60 minutes (P less than 0.05) and 120 minutes (P less than 0.01) and by anoxic conditions after 120 minutes (P less than 0.05). Transmucosal flux from ...
Pleuropneumonia. The historical, clinical, diagnostic, and therapeutic aspects of pleuropneumonia are reviewed with emphasis placed on aggressive treatment and ultrasound diagnosis. The common sequelae are described, and appropriate treatment recommendations are included. A favorable prognosis may be expected for horses receiving long-term treatment.
[The treatment of insertion desmopathy in the metatarsus of horses]. Metacarpal or metatarsal exostoses were diagnosed in 112 horses used for sport purposes between January 1976 to December 1987. Fourteen of these patients were treated surgically by subperiosteal removal of the exostosis. All animals which could be followed up had returned to their original use. The average time of use after discharge from the clinic was 38.4 months. Surgery was successful in completely removing the exostoses in 58.3% of these horses. The indications for anaesthesia and resection of the ulnar nerve are discussed.
Steady-state response characteristics of a pulse oximeter on equine intestine. The steady-state response characteristics of a pulse oximeter were evaluated on intestinal segments of seven clinically normal halothane-anesthetized horses. Arterial oxygen tension greater than 200 mm of Hg, end tidal carbon dioxide from 30 to 35 mm of Hg, and systemic mean arterial pressure greater than 70 mm of Hg were maintained throughout the recording periods. Values for percentage of pulse oximeter oxygen saturation, pulsatile blood flow, and percentage of signal strength were recorded from jejunum, ileum, cecum, left ventral colon, left dorsal colon, and descending colon. Probe placeme...
Field evaluation of a commercial M-protein vaccine against Streptococcus equi infection in foals. A double-blind randomized clinical trial was undertaken to determine the value of parenterally administered Streptococcus equi M-protein vaccine in foals during an epizootic of strangles. Weaned mixed-breed foals (n = 664) housed on 2 adjacent feed-lots (A and B) arrived over a 5-day period, 2 weeks before primary vaccination. Foals in lot B (n = 114) were randomly administered vaccine (n = 59) or saline solution (placebo; n = 55) on 3 occasions at biweekly intervals. Foals in lot A (n = 450) were given 1 dose of vaccine (n = 225) or placebo. The following clinical observations were scored bli...
Upper airway obstruction in performance horses. Differential diagnoses and treatment. Abnormalities of the nasal cavity, pharynx, larynx, and trachea result in respiratory noise and exercise intolerance. Clinical features of common upper respiratory conditions of performance horses are reviewed with emphasis on diagnosis, treatment, and risk factors that affect the outcome of surgical treatment.
[Differentiation and transplantation antigens on the surface of mononuclear cells of cattle, horses and dogs]. The determination of differentiation and transplantation antigens will be of growing importance in immune diagnosis for individual animals as well as for breeding purposes in populations. Differentiation antigens characterize subsets of cell populations and indicate their functional capacity while transplantation antigens represent markers of individuals of a species. Occurrence and significance of these antigenic systems are briefly reviewed.
Spinal cord ischemic necrosis due to fibrocartilaginous embolism in a horse. No abstract available
Cloning the cDNA for horse growth hormone and expression in Escherichia coli. A 514 bp cDNA transcript coding for 78% of horse (Equus caballus.) GH has been cloned and sequenced. The deduced amino acid sequence corresponded precisely to that previously obtained by protein sequencing and, in addition, provided new sequence information for the signal peptide. The missing 3' fragment of the cDNA was reconstructed using synthetic oligonucleotides and site-specific directed mutagenesis. The complete cDNA sequence was then inserted into an expression vector (PIN-III-lppp-5) which utilizes a bacterial signal peptide to secrete the expressed product into the periplasmic space o...
Detection and identification of loline and its analogues in horse urine. Several kinds of loline-type alkaloids, norloline, loline, N-acetylnorloline, N-acetylloline, N-formylnorloline, N-formylloline and N-methylloline were detected in the urine of race-horses. Furthermore, a new compound of the alkaloids, N-senecioylnorloline, was also found and identified. These compounds were mainly identified by means of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-fourier transform-infrared spectrometry (GC-FT-IR). A certain plant of Gramineae containing four kinds of loline-type alkaloids was found in a bale of hay used for the horse forage. The taxono...
[Chlamydia as the cause of abortions in horses]. Between 1982 and 1989 59 equine fetuses were investigated for chlamydiae using animal experiments and embryonated eggs. Chlamydiae were isolated from 16 fetuses (27.1%) originating from 8 studs. The macroscopical lesions of the fetal organs were characterized by extensive haemorrhages. The histological picture shows severe lesions of the blood vessels of different organs. In 6 studs in which chlamydiae had been isolated, blood sera of clinically healthy and pregnant mares were investigated for antibodies during 1989 and 1990. Antibody titres between 1:10++ and 1:40 were detected by using compl...
Upper airway conditions in older horses, broodmares, and stallions. Upper respiratory tract conditions of the older horse that are not necessarily associated with athletic exercise intolerance are discussed. Some of the diseases described include ethmoid hematoma, sinus disease, guttural pouch empyema and mycosis, retropharyngeal abscess, nasopharyngeal cicatrix, arytenoid chondropathy, and neoplasia.
Pathways of lymph flow from the intestine of the horse. The intestine of horses differs from that of most other domestic animals in having a huge ascending colon and cecum, which together act as a large fermentation vat. The lymph drainage from this intestine occurs through a complex network of lymph vessels and lymph nodes, of which there are several thousand. The pathways taken by lymph through these vessels and nodes were studied by tracing injections of dye, by examining Microfil casts, and with light and transmission electron microscopy. Lymph vessels transporting lymph from the intestinal wall generally terminate on a single node within a gro...
Effect of dietary alpha-linolenic acid on endotoxin-induced production of tumor necrosis factor by peritoneal macrophages in horses. A study was conducted to determine whether dietary supplements with alpha-linolenic acid altered the ability of equine peritoneal macrophages to produce tumor necrosis factor (TNF) in response to endotoxin. Peritoneal macrophages were harvested from 6 healthy adult horses before and after the horses were fed a nutritionally balanced ration that contained 8% linseed oil as a source of alpha-linolenic acid. The macrophages were cultured in media containing no additives (control), endotoxin (0.5 to 50 ng/ml), or the calcium ionophore, A23187. Macrophage supernatants were collected after 6 and 24 ...
Additional diagnostic procedures. This article reviews recent diagnostic procedures that have arisen over the last 10 years. Videoendoscopy of horses on a high-speed treadmill allows observation of some of the changes that take place in a horse's airway during exercise. Measurements of upper airway airflows and transupper airway pressure, the use of an esophageal balloon and a Ventigraph to measure changes in pleural pressure, and pulmonary function testing are new techniques that aid the researcher in understanding the mechanics and pathologic characteristics of airway diseases and help the practitioner in assessing the sever...
Clinical examination of the respiratory system. Aspects of a detailed examination of the respiratory system of the horse with suspected respiratory system disease are described. This review includes discussions of the terminology of signs associated with respiratory system disease; radiographic examination of the upper and lower airways and thorax; nuclear scintigraphy; percutaneous and endoscopic tracheal aspiration; bronchoalveolar lavage; electromyography; blood gas analysis; and pleuroscopy and pleural fluid examination.
Determinants of attenuated LH-release associated with the first ovulation of the equine breeding season. An attenuated ovulatory rise in circulating concentrations of LH is characteristically associated with the first seasonal reproductive cycle of horse mares. Unlike ovulations (OV) of subsequent estrous cycles, the first OV of the breeding season (OV1) is not preceded by elevated concentrations of progesterone (PROG). Hence, the ability of pretreatment with PROG to abolish attenuation of LH-secretion associated with OV1 was investigated. Ten nonpregnant anestrous mares were randomly divided into 2 groups; control (C) and treated (T). Per individual, when diameter of the largest follicle was con...
Sarcocystis neurona n. sp. (Protozoa: Apicomplexa), the etiologic agent of equine protozoal myeloencephalitis. Sarcocystis neuronan n. sp. is proposed for the apicomplexan taxon associated with myeloencephalitis in horses. Only asexual stages of this parasite presently are known, and they are found within neuronal cells and leukocytes of the brain and spinal cord. The parasite is located in the host cell cytoplasm, does not have a parasitophorous vacuole, and divides by endopolygeny. Schizonts are 5-35 microns x 5-20 microns and contain 4-40 merozoites arranged in a rosette around a prominent residual body. Merozoites are approximately 4 x 1 micron, have a central nucleus, and lack rhoptries. Schizonts...
Diagnosis and prevalence of leptospira infection in aborted and stillborn horses. A study was conducted to evaluate a recently available fluorescent antibody test (FAT) conjugate for the detection of leptospires in tissues of aborted and stillborn horses, to determine the leptospira antibody titers and compare serologic test results with FAT results, and to determine the prevalence of leptospira-induced abortions and stillbirths in the equine population of central Kentucky. From July 1, 1988 through June 30, 1989, 15 (2.5%) of 594 submissions (fetuses, stillborn foals, and/or placentas) were diagnosed as leptospirosis by the FAT (14 of 15 tested) and/or microscopic agglutin...
Tumor necrosis factor activity in the circulation of horses given endotoxin. Serum and plasma from horses injected with endotoxin was examined for cytotoxic activity. Each of the cell lines, L929 and WEHI 164 clone 13, was sensitive to the cytotoxic effects of equine serum; however, a precipitation artifact caused by the use of isopropanol in the WEHI assay limited the use of this assay to samples containing less than 2 mg of protein/ml. In foals treated with a sublethal IV bolus of 5 micrograms of lipopolysaccharide (LPS)/kg and in adult horses given a low-dose continuous infusion of LPS (30 ng/kg/h for 4 hours), cytotoxic activity was detected in all serum or plasma ...
Prognostic features and clinical presentation of acute idiopathic enterocolitis in horses. Clinical and hematological changes observed on presentation of 47 horses referred to the Ontario Veterinary College with acute idiopathic colitis were analyzed for their prognostic features. Cases of acute enterocolitis were characterized by fever, dehydration, abnormalities of serum electrolyte concentrations, azotemia, hypoalbuminemia, and increased serum concentrations of muscle enzymes. Severely dehydrated horses were seven times more likely to die or be euthanized than those that were not dehydrated. Other factors associated with failure to survive included the following: increased hemato...
Reverse-phase ion-pairing high-performance liquid chromatography of phosphocreatine, creatine and creatinine in equine muscle. A simple, robust and reproducible analytical method for the determination of phosphocreatine (PCr), creatine (Cr) and creatinine (Cn) in equine skeletal muscle is presented. The technique used isocratic reverse-phase ion-pairing high-performance liquid chromatography. Neutralized perchloric acid extracts of equine muscle biopsies were analysed and the values obtained were compared with determinations from an established enzymic procedure. Good resolution of all three metabolites was achieved within a retention time of less than 11 min. Linearity for each metabolite within the concentration ran...
Bacterial pneumonia. Bacterial pneumonia in the horse often occurs secondary to viral respiratory infection; however, primary infections can occur. A diagnosis of bacterial pneumonia is made on the basis of history, physical examination, and laboratory and radiographic findings. Treatment consists of appropriate antimicrobial therapy for at least 7 to 10 days; further therapy may be needed in more severe cases. Prevention of bacterial pneumonia includes attempting to prevent viral respiratory infections and appropriate management to prevent stress to the respiratory tract.
Upper respiratory obstruction in foals, weanlings, and yearlings. Upper airway obstruction may result from nasal, pharyngeal, or tracheal diseases. In the young horse, a relatively severe obstruction usually is present before clinical signs are evident. This article reviews the clinical manifestations, diagnostic features, treatment, and outcome of commonly encountered conditions of the nasal passages, pharynx, larynx, and trachea in young horses.
