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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.
Rhodococcus equi-infected macrophages are recognized and killed by CD8+ T lymphocytes in a major histocompatibility complex class I-unrestricted fashion. The goal of this research was to examine the role of cytotoxic T lymphocytes (CTL) in the control of Rhodococcus equi and specifically to determine if R. equi-specific CD8+ CTL occurred in the blood of immune horses. Equine peripheral blood mononuclear cells stimulated with antigen-presenting cells either infected with R. equi or exposed to soluble R. equi antigen lysed R. equi-infected target cells. Lysis was decreased to background by depletion of either CD2+ or CD3+ cells, indicating that the effector cell had a T-lymphocyte, but not NK cell, phenotype. Stimulation induced an increased perc...
Hysteroscopic or rectally guided, deep-uterine insemination of mares with spermatozoa stored 18 h at either 5 degrees C or 15 degrees C prior to flow-cytometric sorting. Practical application of sex-selected spermatozoa in the horse industry would be greatly improved by the ability to develop simplified methods for shipping, storing, and inseminating sex-selected spermatozoa. Acceptable pregnancy rates have been achieved using fresh sex-sorted stallion sperm, however many stallion owners are reluctant to send their stallions to the sorter location for collection during the breeding season. Furthermore, the technology would be more applicable if the hysteroscopic insemination technique was not necessary for adequate pregnancy rates. Hysteroscopic insemination r...
Direct detection of boldenone sulfate and glucuronide conjugates in horse urine by ion trap liquid chromatography-mass spectrometry. A study of the equine phase II metabolism of the anabolic agent boldenone is reported. Boldenone sulfate, boldenone glucuronide and their C17-epimers were synthesised as reference standards in our lab and a method was developed for their detection in a horse urine matrix. Solid phase extraction was used to purify the analytes, which were then detected by ion trap LC/MS. Negative and positive ionisation mode MS(2) were used for the detection of sulfate and glucuronide conjugates, respectively. Boldenone sulfate and 17-epiboldenone glucuronide were detected as the major and minor phase II metabo...
An oral choristoma in a foal resembling hairy polyp in humans. A neonatal foal was presented with a 6.5-cm pedunculated mass arising from the upper deciduous incisors. The distal end was soft and covered by haired skin, whereas the proximal end was firm, covered with mucosal epithelium, and at the point of transection contained a fully developed tooth. Microscopically, the mass was covered by epidermis and mucosal epithelium and the remaining portion of the mass consisted of mature collagen, nonneoplastic fat and smooth muscle, and a single tooth within a bony socket. The mass is consistent with an oral choristoma and has features similar to those describ...
Surgical management of compound odontoma in two horses. Two horses were admitted for evaluation of mandibular swelling (horse 1) or maxillary distortion (horse 2). Both horses had radiographic evidence of tumors of dental origin that had the appearance of a compound odontoma. Extensive surgical resection was performed for treatment. Horse 1 was treated with 1-stage surgical resection, but an iatrogenic fracture occurred during surgery, which was managed successfully with a type I external fixator and extraoral alimentation. Horse 2 was treated in multiple stages to remove all portions of the tumor. To manage an extensive orosinal fistula, a custom-...
Congenital cystic polypoid rectal hamartoma in a newborn foal. A neonatal foal with signs of rectal bleeding was diagnosed with an intraluminal rectal mass and intussusception on surgical exploration of the abdomen. Histologically, the mass consisted of cystic spaces lined by simple columnar epithelium with numerous goblet cells and was surrounded by thin bands of smooth muscle in a myxomatous stroma. Although the mass shared similarities with retrorectal cystic hamartoma (tailgut cyst) and juvenile polyps, described in human medicine, location and histologic findings were not entirely consistent with either condition.
Heterogeneity of the neuropeptide Y (NPY) contractile and relaxing receptors in horse penile small arteries. The distribution of neuropeptide Y (NPY)-immunorective nerves and the receptors involved in the effects of NPY upon electrical field stimulation (EFS)- and noradrenaline (NA)-elicited contractions were investigated in horse penile small arteries. NPY-immunoreactive nerves were widely distributed in the erectile tissues with a particularly high density around penile intracavernous small arteries. In small arteries isolated from the proximal part of the corpora cavernosa, NPY (30 nM) produced a variable modest enhancement of the contractions elicited by both EFS and NA. At the same concentration...
Study of caffeine in urine and saliva of horses subjected to urinary acidification. The study of caffeine in racing horses has been of growing concern in veterinary sports medicine since the Association of Racing Commissioners International (ARCI) stated that it has no valid therapeutic use in racehorses. We examined the kinetic alterations in the urinary excretion and salivary secretion of caffeine in seven horses subjected to urinary acidification using ascorbic acid because this procedure can simulate the acidosis that follows anaerobic exercise. They participated in two treatment groups: the control group (SG) received 500 ml of saline and then 2.0 mg kg(-1) caffeine i.v....
Use of a non-traditional university ambulatory practice to teach large animal medicine. While many other veterinary schools have moved away from a traditional university-based ambulatory practice, the Ohio State University's Large Animal Practice has continued to provide a cost-effective and valuable method of preparing students for today's careers in veterinary medicine. The practice provides a full array of services to production, equine, and camelid clients, including herd health, individual animal medicine and surgery, and emergency services. Acquiring established practices from alumni has formed the client base. Four full-time veterinarians operate the clinic. While these sa...
Sensitivity of commercial prothrombin time reagents to detect coagulation factor deficiencies in equine plasma. The sensitivity of commercial prothrombin time (PT) tests was assessed based on a dilution series of equine pooled plasma (EPP) (experiment 1) and on 40 equine plasma samples with reduced activity of coagulation factors II, V, VII and X (experiment 2). Two different PT reagents (reagent 1, human placental thromboplastin; reagent 2, recombinant human tissue factor) were used according to the manufacturers' instructions (standard test, PT([ST])) and compared to a modified test procedure (modified test, PT([MT])) using sample dilution and fibrinogen addition. In all samples, sensitivity was lower...
Comparative histopathology of grey-horse-melanoma and human malignant melanoma. Equine melanoma shows striking features particularly with regard to clinical development in grey horses: in contrast to malignant melanoma in humans and in solid coloured horses that are characterized by early onset of metastasis, pigment cell tumours display almost benign clinical features in ageing grey horses. Through evolution, grey horses appear to be in a favourable position in regard to the biological behaviour of melanomas. Yet unknown factors inhibiting or retarding early melanoma metastasis may be responsible for this phenomenon. In this study, immunostaining profiles and histopathol...
CYP3A in horse intestines. The intestinal enterocytes provide the initial site for cytochrome P450 (CYP)-mediated metabolism of orally absorbed xenobiotics. In man and some animal species, the CYP3A subfamily is highly expressed in the intestines and considered to be important in the first-pass metabolism of drugs and other xenobiotics. The aim of the present study was to investigate the mRNA expression, immunohistochemical localization and catalytic activity of CYP3A in the intestines of horse. Real-time RT-PCR analyses showed that the highest CYP3A mRNA expression was present in the duodenum with a decreasing level to...
Evaluation of clinical and laboratory variables as prognostic indicators in hospitalised gastrointestinal colic horses. The present prospective study included 106 horses referred to the Department of Large Animal Sciences, The Norwegian School of Veterinary Science, as non-responders to the initial colic treatment in general practise. In 14 of these cases a required surgical treatment was not performed due to economical or other reasons and were excluded from the study. Clinical and laboratory data were obtained at the arrival in the hospital. The outcome for all analyses was survival/ non-survival. A multivariable logistic regression was performed. The analyses were used in medically (46 horses) and surgically...
Serological method using recombinant S2 protein to differentiate equine infectious anemia virus (EIAV)-infected and EIAV-vaccinated horses. We recently reported a highly protective attenuated live virus vaccine for equine infectious anemia virus (EIAV) based on a proviral construct (EIAVUKDeltaS2) with a genetically engineered mutation in the viral S2 gene that eliminates expression of this accessory protein. While the EIAVUKDeltaS2 vaccine provides protection from detectable infection by experimental challenge with highly virulent virus, the potential for commercial application of this vaccine is complicated by the fact that horses inoculated with the EIAVUKDeltaS2 vaccine strain become seropositive in various reference diagnosti...
Effect of chronic clenbuterol administration and exercise training on immune function in horses. Effects of longitudinal exercise training and acute intensive exercise (simulated race test) on immune function have not been reported in horses. Clenbuterol, a beta2-adrenergic agonist, is used to manage inflammatory airway disease in horses. This study investigated the interaction of 8 wk of exercise training with or without 12 wk of clenbuterol administration in horses. Twenty-three untrained standardbred mares (10 +/- 3 yr, Mean +/- SE) were used and divided into four experimental groups. Horses given clenbuterol plus exercise (CLENEX; n = 6) and clenbuterol alone (CLEN; n = 6) received 2....
Effect of diet composition and feeding pattern on the prececal digestibility of starches from diverse botanical origins measured with the mobile nylon bag technique in horses. This trial was conducted to determine the extent of prececal starch digestibility depending on the botanical origin of starch and on diet characteristics (i.e., composition and feeding pattern). The prececal disappearance of six substrates (oats, barley, corn, horse bean, potato, and wheat) was measured in four cannulated horses fed (as-fed basis) 11.8 g/kg BW of a high-fiber (HF) or high-starch (HS) pelleted feed and 10.0 g/kg BW of meadow hay using the mobile bag technique (MBT). The daily feeding pattern was either three meals (two meals of pellets and one meal of hay) or five meals (three ...
Septic tenosynovitis of the tarsal sheath of an Arab gelding and suspected sepsis of the lateral digital flexor tendon subsequent to bacterial peritonitis. A 21-year-old Arab gelding with clinical signs of acute peritonitis had a perforating ulcer on the mesenteric border of the jejunum which resulted in localised contamination of the abdomen with ingesta. The affected segment of jejunum was resected and the abdomen was lavaged extensively. Postoperatively, the gelding was treated with broad-spectrum antibiotics, non-steroidal anti-inflammatory drugs and intravenous fluids, but after four days it became acutely non-weight bearing on its right hindlimb, and a tendonitis of the lateral digital flexor tendon within the tarsal sheath was identified u...
Compensatory load redistribution of horses with induced weight-bearing forelimb lameness trotting on a treadmill. The study was performed to obtain a detailed insight into the load and time shifting mechanisms of horses with unilateral weight-bearing forelimb lameness. Reversible lameness was induced in 11 clinically sound horses by applying a solar pressure model. Three degrees of lameness (subtle, mild and moderate) were induced and compared with sound control measurements. Vertical ground reaction force-time histories of all four limbs were recorded simultaneously on an instrumented treadmill. Four compensatory mechanisms could be identified that served to reduce structural stress, i.e. peak vertical f...
Pre-operative and anaesthesia-related risk factors for mortality in equine colic cases. Mortality rates for horses that have undergone emergency abdominal surgery are higher than for other procedures. Here, multivariable modelling of data from 774 surgical colic cases is used to identify pre-operative and anaesthesia-related variables associated with intra- and post-operative mortality. Intra-operative mortality was significantly (P<0.05), and positively associated with heart rate and packed cell volume (PCV) at admission, and negatively associated with the severity of pain. Post-operative mortality increased with increasing age and PCV at admission. Draught horses, Thoroughbr...
Factors associated with the prevalence of osseous fragments in the limb joints of Hanoverian Warmblood horses. Factors associated with the prevalence of osseous fragments (OF) in fetlock and hock joints were investigated in a population of young Hanoverian Warmblood horses selected for sale at auction from 1991 to 1998. The study was based on results of a standardized radiological examination of 3127 horses. The prevalences of OF in the two joints were significantly dependent on the date, type and quality of the auction, the region of origin and on the anticipated suitability of the horses for dressage and/or show-jumping. The probability of finding OF increased with wither-height. Furthermore, there w...
An analgesic evaluation of isoxsuprine in horses. Isoxsuprine is used clinically to treat navicular disease and laminitis in horses. Although it is thought to increase digital and laminar blood flow, isoxsuprine's mechanism of action remains controversial, and analgesia has been suggested recently as such possible mechanism. This research investigated the analgesic potential of isoxsuprine in healthy horses submitted to a mechanical nociceptive test. Isoxsuprine (1.2 mg/kg), xylazine (1.1 mg/kg), distilled water : ethanol 95% (2 : 1, v/v, 20 ml) and saline (0.9%, 20 ml) were injected intravenously, and nociceptive thresholds were measured ove...
Fibrocartilaginous embolic myelopathy in a horse. Fibrocartilaginous embolic myelopathy was diagnosed in a 11-year-old, male, Tennessee Walking Horse by histopathological examination of the spinal cord after the horse was killed because of severe neurological dysfunction. Both ventral funiculi of C6 and C7 cervical spinal cord had extensive necrosis with blood vessels containing fibrocartilaginous emboli. A similar fibrocartilaginous embolus was observed in a single large spinal artery adjoining the vertebral leptomeninges.
Foal IgG and opsonizing anti-Rhodococcus equi antibodies after immunization of pregnant mares with a protective VapA candidate vaccine. The aim of this study was to evaluate serum IgG antibody levels and opsonizing activity in foals from pregnant mares immunized with either proteins from an R. equi strain containing virulence-associated protein A (VapA), an immunodominant surface-expressed lipoprotein encoded by a virulence plasmid crucial for virulence in foals, or a whole killed virulent R. equi preparation. Forty-eight pregnant mares were distributed into three groups, i.e. 24 immunized with R. equi VapA protein antigen associated with a water-based nanoparticle adjuvant (Montanide IMS 3012), 8 immunized with whole killed R...
Biomechanical and energetic determinants of the walk-trot transition in horses. We studied nine adult horses spanning an eightfold range in body mass (M(b)) (90-720 kg) and a twofold range in leg length (L) (0.7-1.4 m). We measured the horses' walk-trot transition speeds using step-wise speed increments as they locomoted on a motorized treadmill. We then measured their rates of oxygen consumption over a wide range of walking and trotting speeds. We interpreted the transition speed results using a simple inverted-pendulum model of walking in which gravity provides the centripetal force necessary to keep the leg in contact with the ground. By studying a large size range of ...
[Life threatening intestinal bleeding in a Bearded Collie associated with a food supplement for horses]. In a Bearded Collie with acute weakness, hematemesis, melena, painful abdomen and pale mucous membranes a hematocrit of 13% and panhypoproteinemia were found. This combination of findings was the manifestation of severe gastrointestinal bleeding. Despite intensive laboratory and imaging investigations no systemic or local cause could be identified. After repeated client interrogation it was found that the dog had been receiving a food supplement for equines. It was further detected that this supplement besides a shell extract also contained willow (Salicaceae) and meadowsweet (Filipendula, Spi...
Effects of alpha2-adrenergic receptor agonists on urine production in horses deprived of food and water. To quantitate the dose- and time-related effects of IV administration of xylazine and detomidine on urine characteristics in horses deprived of feed and water. Methods: 6 horses. Methods: Feed and water were withheld for 24 hours followed by i.v. administration of saline (0.9% NaCI) solution, xylazine (0.5 or 1.0 mg/kg), or detomidine (0.03 mg/kg). Horses were treated 4 times, each time with a different protocol. Following treatment, urine and blood samples were obtained at 15, 30, 60, 120, and 180 minutes. Blood samples were analyzed for PCV and serum concentrations of total plasma solids, so...
Effects of ischemia and the cyclooxygenase inhibitor flunixin on in vitro passage of lipopolysaccharide across equine jejunum. To determine whether ischemia and flunixin affect in vitro lipopolysaccharide (LPS) absorption in samples of the jejunum of horses. Methods: 12 horses. Methods: Horses were anesthetized, a midline celiotomy was performed, and the jejunum was located. Two 30-cm sections of jejunum (60 cm apart) were selected. One segment was designated as control tissue; ischemia was induced in the other segment for 120 minutes. Horses were then euthanatized. Mucosa from each jejunal segment was mounted on Ussing chambers and treated with or without flunixin. Tissues from 6 horses were used to assess permeabili...
Use of computed tomography angiography to evaluate the vascular anatomy of the distal portion of the forelimb of horses. To provide a detailed description of the vascular anatomy of the distal portion of the forelimbs of horses by use of computed tomography angiography (CTA). Methods: 6 forelimbs of 5 horses and 1 forelimb from an equine cadaver; none of the horses had orthopedic or vascular disease. Methods: Horses were anesthetized and CTA was conducted on the dependent forelimb. A catheter was inserted in the median artery, and contrast medium was infused at a rate of 3 mL/s. A computed tomography (CT) scanner was used to obtain contiguous slices from the region of the proximal sesamoid bones to the toe. All ...
