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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.
Developmental regulation of class I major histocompatibility complex antigen expression by equine trophoblastic cells. Between days 36-38 of pregnancy equine trophoblastic cells of the chorionic girdle migrate and form endometrial cups. Just prior to invasion, the chorionic girdle cells express high levels of polymorphic, paternally inherited, major histocompatibility complex (MHC) class I antigens. Their descendents, the mature, invasive trophoblast cells of the endometrial cups, however, express low or undetectable levels of MHC class I antigens by day 44 of pregnancy. Experiments with MHC compatible pregnancies, the study of residual chorionic girdle cells that had failed to invade the endometrium and remai...
Specialized veins in the submucosa of the equine ileocecal junction. Spirally arranged bundles of sub-endothelial smooth muscle enfold the small to medium-sized submucosal veins in the equine ileocecal junction. The muscle bundles, accompanied by the endothelial lining, bulge into the lumen of the vessels, partly occluding the latter. Transmission electron microscopy of the muscle cells reveals features consistent with vascular smooth muscle ultrastructure. It is proposed that the throttling effect of the muscle bundles causes engorgement of the submucosal venous plexus, which then assists in the closing of the ileocecal orifice.
Normal equine ocular anatomy and eye examination. When compared with small domestic animals, the horse has unique ocular characteristics (complete bony orbit, well-developed eyelid muscles, a nasal and temporal gray limbal line, granulae iridica, paurangiotic fundus). Knowledge of normal equine ocular anatomy is essential for ocular lesion interpretation. It is important to obtain a full history and general examination before sedation, nerve blocks, or other diagnostic ophthalmic tests are performed. All ocular examinations should include a systematic evaluation of both the anterior and posterior segments. Selection of other diagnostic tests ...
Equine ulcerative keratitis. Ulcerative keratitis is one of the most common vision-threatening diseases of the horse. Successful therapy, however, can be achieved in the majority of cases provided the diagnosis is made early and the treatment is specific for the disease. This article reviews the pathophysiology, clinical signs, and contemporary medical and surgical approaches to bacterial and fungal ulcerative keratitis in the horse.
Use of a semi-quantitative sweat test in thoroughbred horses. A practical test for evaluating the sweating response to various concentrations of the specific beta 2 agonist, salbutamol sulphate, is described. The results of performing this test on horses (n = 54) considered to be "free sweaters", horses (n = 6) that showed signs of heat stress following exercise, and horses with complete anhidrosis (n = 2) are presented. The results indicate that intradermal injections of 0.1 ml of salbutamol sulphate at dilutions of 10(-7) or less are suitable stimuli to elicit a visually detectable local sweating in horses with a normal sweating response. Horses that o...
Quantitative analysis of computer-averaged electromyographic profiles of intrinsic limb muscles in ponies at the walk. The function of several intrinsic muscles of the fore-and hind limbs of 5 ponies walking normally was evaluated via surface electromyography. Electromyographic signals were band-pass filtered, rectified, linear enveloped, and standardized to the stride duration. Mean data from the muscles of the left and right limbs that were obtained from at least 30 strides in 2 recording sessions were recorded as electromyographic signals-time curves. The timing of muscle activity was determined from these graphs. On the basis of the major peaks in the electromyographic signal, muscle functions were identif...
[Parasitic helminths of the cecum and colon of equidae in Italy]. Intestinal helminths from coecum and colon were studied in 93 equidae including 40 horses, 36 donkeys and 17 mules. A total of 38 species, 36 nematodes and 2 cestodes, were identified as follows: 1) Triodontophorus serratus, 2) Triodontophorus brevicauda, 3) Strongylus equinus, 4) Strongylus edentatus, 5) Strongylus vulgaris, 6) Cyathostomum tetracanthum, 7) Cyathostomum coronatum, 8) Cyathostomum labiatum, 9) Cyathostomum labratum, 10) Cyathostomum alveatum, 11) Cyathostomum pateratum, 12) Cyathostomum catinatum, 13) Cyathostomum sagittatum, 14) Cylicodontophorus bicoronatus, 15) Cylicocyclus...
Histological features of the dorsal cortex of the third metacarpal bone mid-diaphysis during postnatal growth in thoroughbred horses. The dorsal cortex of the equine third metacarpal mid-diaphyseal bone was characterised during growth by the histological and microradiographic examination of specimens from 30 horses ranging in age from 2 months to 8 y. Bone from horses aged less than 6 months was characterised by rapid periosteal apposition of circumferential trabeculae of woven bone that were next connected by radial trabeculae to the parent cortex. Deposition of lamellar bone on the inner trabecular surfaces resulted in rows of primary osteons. Replacement of primary bone occurred only after 4 months of age and preferential...
Basis for regulation of selenium supplements in animal diets. Selenium was discovered 174 yr ago but, until 1957, was given little notice by biologists or was vilified as an agent that caused toxicity in grazing ruminants and horses in the northern Great Plains. After its status as an essential nutrient was established, Se received intense scrutiny, and hundreds of papers have been published dealing with its metabolic functions and the consequences of a Se deficiency. Because regions of Se deficiency are so extensive in the United States, great efforts have been made to gain Food and Drug Administration (FDA) approval for Se supplementation of animal die...
Distribution studies of theophylline: microdialysis in rat and horse and whole body autoradiography in rat. After intravenous administration of theophylline, microdialysis has been used for studying the non protein bound theophylline concentration in blood and in lung tissue in the rat as well as in two horses. The distribution pattern of 14C-theophylline in the rat was also investigated. When the distribution of theophylline was completed the time course of free drug in the interstitial fluid in lung tissue was in good agreement with the total concentration-time profile in plasma in both species. In the rat the free concentration of theophylline in the lung was slightly lower than the free concentr...
Diagnosis and treatment of lens diseases. The lens represents a unique tissue in light of its embryologic development, retention of old cells and nuclear make-up, transparent nature, immune privileged status, and metabolic restrictions. Disorders of malformation and malposition occur, but cataract development is the most common and significant problem for owners and animals. Technologic and pharmacologic advances have allowed surgical removal of equine cataracts to become an acceptable alternative, capable of returning a visually impaired horse to a functional status. Uveal inflammation represents the greatest threat to successful sur...
Equine tumor necrosis factor alpha: cloning and expression in Escherichia coli, generation of monoclonal antibodies, and development of a sensitive enzyme-linked immunosorbent assay. We describe the production and purification of recombinant equine tumor necrosis factor alpha (rETNF alpha), generation and characterization of murine monoclonal antibodies (Mabs) and rabbit polyclonal antibodies (Pabs) against ETNF alpha, and development of a sensitive enzyme-linked immunosorbent assay (ELISA). Genomic-derived DNA sequences encoding mature ETNF alpha were reconstructed by the polymerase chain reaction (PCR) and oligonucleotide-directed mutagenesis and were cloned into the vector pFLAG-1 for expression in Escherichia coli. rETNF alpha was purified by anti-FLAG immunoaffinity c...
Presence of pulmonary intravascular macrophages in the equine lung: some structuro-functional properties. The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin-sensitive globular coat from PIMs of calf, goat, and sheep. Monast...
[Prenatal development of the horse ovary]. To answer the many open questions concerning the development of the horse's ovary, first the prenatal development was investigated. It resulted that follicles derive from the germinal epithelium and its cords, whereas the Leydig cells and the rete blastema originate from the mesonephros. In the second third of pregnancy the Leydig cells undergo an enormous proliferation, in the last third they degenerate. However this degeneration is not connected with the postnatal development of the ovulation groove.
Visual acuity in the horse. We assessed the ease with which horses could learn visual discriminations and measured their resolution acuity. We trained three horses to press their noses against one of two large wooden panels to receive a small food reward. Following training on a series of two-choice discrimination tasks, resolution acuity was measured. Although there was some variability between animals, the best acuity obtained was 23.3 c deg-1. Within the margin of error imposed by limited anatomical data, the obtained values are consistent with predictions based on retinal ganglion cell density estimates and posterior...
Pharmacokinetics, penetration into cerebrospinal fluid, and hematologic effects after multiple oral administrations of pyrimethamine to horses. Pharmacokinetics, CSF penetration, and hematologic effects of oral administration of pyrimethamine were studied after multiple dosing. Pyrimethamine (1 mg/kg of body weight) was administered orally once a day for 10 days to 5 adult horses, and blood samples were collected frequently after the first, fifth, and tenth doses. The CSF samples were obtained by cisternal puncture 4 to 6 hours after administration of the first, third, seventh, and tenth doses. Pyrimethamine concentration in plasma and CSF was quantified by gas chromatography, and plasma concentration-time data were analyzed, using a ...
Effect of treatment with oxytetracycline during the acute stages of experimentally induced equine ehrlichial colitis in ponies. Eighteen ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocyte cells. Twenty-four hours after onset of fever (rectal temperature > 38.8 C), 9 ponies were treated with oxytetracycline (6.6 mg/kg of body weight, IV, q 24 h) for 5 days. The remaining 9 ponies served as infected nontreated controls. Mean scores of the following variables were not significantly different between groups on the day treatment was begun: rectal temperature, diarrhea, borborygmal sounds, feed intake, mental attitude, and evidence of a hyperresonant area in the abdomen. All ponies were observed...
Influence of exogenous progesterone on early embryonic development in the mare. The influence of exogenous progesterone on the development of equine oviductal embryos was determined based upon the recovery of Day-7 uterine blastocysts from treated mares (n=13) that were given 450 mg progesterone daily between Days 0 and 6 and from untreated control mares (n=13). Daily administration of 450 mg progesterone in oil significantly (P<0.02) increased serum progesterone concentrations in the treated mares. There was no significant difference in the recovery rate of Day-7 embryos between treated and control mares (8/13 versus 6/13, respectively). Embryonic development, assesse...
Relationship between colloid osmotic pressure and plasma protein concentration in cattle, horses, dogs, and cats. The relationship between colloid osmotic pressure (COP) and protein concentration was investigated for purified proteins and plasma samples obtained from cattle, horses, dogs, and cats. At equivalent concentrations, bovine albumin exerted a COP that exceeded that of gamma-globulins by a mean factor of 4.4. Similar relationships between COP and protein were observed in the other species. Consequently, for a given total protein concentration, COP was dependent on the albumin/gamma-globulins ratio. A commonly used nomogram for estimating COP from protein concentration, the Landis-Pappenheimer equ...
Ocular trauma. Horses with ocular trauma frequently present as emergency cases. This article provides a succinct review of various adnexal and globe injury issues. Accurate case assessment, management, prognosis, and follow-up considerations are presented.
The inhibitory effect of furosemide on the contractile response of equine trachealis to cholinergic nerve stimulation. The effects of furosemide on the responses of equine trachealis muscle with and without epithelium to electrical field stimulation (EFS) and exogenous acetylcholine (ACh) were investigated in organ baths. Tissues were pretreated with guanethidine and the parameters used for EFS were those previously demonstrated to activate postganglionic cholinergic neurons. In tissues with intact epithelium, furosemide (100 microM) shifted the frequency-response curve to the right. In the preparations without epithelium, furosemide did not affect the response to EFS. Neither in epithelium-on nor in epitheliu...
Equine uveitis. Uveitis (inflammation of the iris, ciliary body, or choroid) is a potentially blinding condition with a significant economic impact on the horse industry. Variable symptoms are described, as well as a considerable range of structural and functional sequelae. Known causes of initial episodes include bacterial, viral, traumatic, and parasitic insults, with recurrence by immunologic mechanisms. Treatment strategies and management recommendations that may reduce the incidence or severity of episodes are discussed.
Isolation, propagation, and cryopreservation of equine articular chondrocytes. Equine articular chondrocytes were isolated from explant cartilage cultures by digestion in a 0.075% collagenase solution for 15 to 19 hours. Cartilage from late-term fetal and neonatal foals resulted in mean chondrocyte yield of 51.99 x 10(6) cells/g of cartilage (wet weight), compared with a yield of 17.83 x 10(6) cells/g for foals 3 to 12 months old. Propagation of chondrocytes in monolayer and 3-dimensional culture was accomplished, using Ham's F-12 as the basal medium, with supplements of fetal bovine serum (10%), ascorbic acid, alpha-ketoglutarate, and L-glutamine. The medium was buffere...
Molecular evidence for the origin of the widespread Venezuelan equine encephalitis epizootic of 1969 to 1972. Venezuelan equine encephalitis (VEE) virus is a mosquito-borne pathogen that has caused encephalitis in equine species and humans during sporadic outbreaks in the western hemisphere. The last, and most widespread, VEE outbreak occurred in South America, Central America, Mexico and the U.S.A. (Texas) during 1969 to 1972. We have cloned and sequenced the genome of a virulent VEE subtype I-AB virus, strain 71-180, isolated in Texas in 1971. Thirty-four nucleotide differences were detected between the genome of 71-180 virus and that of the subtype I-AB Trinidad donkey (TRD) virus isolated during t...
Variability of alpha-tocopherol values associated with procurement, storage, and freezing of equine serum and plasma samples. Recent evidence concerning the pathogenesis of equine degenerative myeloencephalopathy indicated that low blood alpha-tocopherol values are a factor in the disease process. Variables that could be introduced by a veterinarian procuring, transporting, or storing samples were evaluated for effects on alpha-tocopherol concentration in equine blood. These variables included temperature; light; exposure to the rubber stopper of the evacuated blood collection tube; hemolysis; duration of freezing time, with and without nitrogen blanketing; and repeated freeze/thaw cycles. It was found that hemolysis...
Ocular cosmetic and prosthetic devices. Specific details on surgical procedures, although not covered here, are available in other references. Factors enhancing the overall cosmetic appearance obtained with procedures are emphasized, providing information that should allow veterinarians to offer clients a good cosmetic appearance and effective treatment for disfiguring ocular problems in their horses. Questions regarding procedures should be addressed to your referral ophthalmologist or, in the case of a corneoscleral prosthesis, the ocularist assisting.
Effect of xylazine on the arrhythmogenic dose of epinephrine in thiamylal/halothane-anesthetized horses. The effect of xylazine on the arrhythmogenic dose of epinephrine (ADE) was studied in 9 horses. Anesthesia was induced by administration of guaifenesin (50 mg/kg of body weight, IV) followed by thiamylal (4 to 6 mg/kg, IV) and was maintained at 1 minimal alveolar concentration (MAC) of halothane (0.89%). Base apex ECG and facial artery pressure were recorded. Epinephrine was infused in a sequence of arithmetically spaced increasing rates (initial rate 0.25 micrograms/kg/min) for a maximum of 10 minutes. The ADE was defined as the lowest epinephrine infusion rate to the nearest 0.25 micrograms/...
Cardiopathological observation on a case of persistent ventricular tachycardia in a pony mare. A 20-year-old pony mare with persistent ventricular tachycardia (VT) was examined cardiopathologically. At necropsy, the heart was enlarged and rounded with both ventricular dilatation. In a longitudinal section of the ventricular septum, a large grayish white patchy lesion (5 x 25 mm) was detected in the relatively higher portion. Microscopically, the lesion was extensive myocardial fibrosis located in the vicinity of the proximal part of the left bundle branch. Partially the fibrotic lesion was in contact with the branch. Such a lesion might play an important role in creating a suitable back...
Exogenous but not endogenous PGE2 modulates pony tracheal smooth muscle contractions. The modulatory role of prostaglandin E2 (PGE2) was examined in pony tracheal smooth muscle strips. Although exogenous PGE2 inhibited the contractile response to both electrical field stimulation (EFS) and acetylcholine (ACh) in a dose-dependent manner, the concentration required to inhibit the response to EFS (10 nM) was less than that required to inhibit the response to ACh (0.1 microM). Cyclooxygenase inhibition with aspirin or meclofenamate had no effect on either the response to EFS or to ACh even though PGE2 production was inhibited. Our results demonstrate that in ponies as in other spec...
