In vivo studies involving horses refer to research conducted within living organisms to understand various biological processes, disease mechanisms, and therapeutic interventions in equine species. These studies provide insights into the physiological and pathological responses of horses under natural conditions. In vivo research encompasses a range of investigations, including pharmacokinetics, disease modeling, and the evaluation of treatment efficacy. It often involves the use of controlled environments to simulate real-life scenarios while observing the effects of specific variables on equine health. This page gathers peer-reviewed research articles and scholarly studies that explore the methodologies, findings, and implications of in vivo research in horses, contributing to the advancement of equine science and veterinary medicine.
Phaneuf LP, Grivel ML, Ruckebusch Y.The electrical potentials were recorded from the antrum, the duodenum, the ileum and the first part of the colon of ponies under (a) normal resting conditions, (b) during nonpainful colic and (c) after intravenous morphine administration. The normal pony, at rest, had five contractions of the antrum per minute. On the small intestine, the basal electrical activity decreased from the duodenum (14-15/min) to the ileum (10-11/min). The small bowel also had three types of motility: peristaltic waves, rhythmic segmentations and random contractions. On the colon, bursts of potentials indicating inte...
Anderson RS, Day NK, Good RA.Natural hemagglutinin activity against vertebrate erythrocytes is present in the hemolymph of the cockroach Blabarus craniifer. The hemagglutinin titer against rabbit erythrocytes is high, whereas sheep and horse red cells agglutinate weakly. Hemagglutinin activity was depressed by the complement inhibitor, cobra venom factor. Cockroach hemagglutinin is heat-labile; all activity is destroyed by heating at 56 C for 1 hr. A humoral factor similar to the complement component 3 proactivator is also present in cockroach hemolymph. The formation of the cobra venom factor-hemolymph "complex" is depen...
Cabasso VJ, Nieman R, Schroeder DD, Hok KA, Louie RE, Mozen MM.A horse has been immunized with Australia antigen (Au/SH) purified 20-fold by a procedure employing gel filtration of Cohn fraction IV derived from an Au/SH-positive human plasma pool. Hyperimmunization was initiated by the intramuscular injection of 20 ml of a mixture of equal parts of purified Au/SH and complete Freund's adjuvant. The 20-ml volume was divided into four 5-ml doses, two of which were administered on each side of the horse's neck. Booster doses of antigen alone were given as follows: 10 ml intravenously 30 days later and 5 ml intramuscularly on each of days 77 and 205. Au/SH an...
Gruber J.Purified and concentrated Venezuelan equine encephalitis (VEE) virus derived from tissue cultures, rendered noninfectious by ionizing radiation with retention of in vitro serological activity, also retained a high level of immunogenicity. In mice, fluid vaccines afforded excellent protection against lethal challenge with homologous Trinidad strain VEE virus. A direct relationship was observed between concentration of vaccine or number of injections and survival. One intraperitoneal inoculation of undiluted vaccine protected essentially all mice challenged 21 days later with 100,000 mouse intra...
Greenaway EC, Sepulveda MF, Cunningham FM, Goode NT.Eosinophils have been implicated in the pathogenesis of the seasonal equine allergic skin disease, sweet itch. Protein kinase C (PKC) is involved in regulating eosinophil function and antigen challenge has been reported to alter PKC isotype expression in blood eosinophils from allergic human subjects. Here we have compared the pattern of PKC isotype expression in eosinophils from sweet itch ponies with that in cells from normal ponies both during the active and inactive phases of the disease. A role for PKC in histamine-induced eosinophil activation was also investigated. Conventional PKCs alp...
Adrian AM, Koene M, Roberts S, Doughty P, Bolas N, Kinns J, Brehm W, Gerlach K.The extent of fat suppression using short tau inversion recovery (STIR) imaging is variable between horses. Our aim was to determine if patient's age and/or hoof temperature have an influence on the T(1) relaxation time of bone marrow in the equine distal limb, thereby affecting the suppression of fat signal. Magnetic resonance imaging was conducted on standing horses and cadaver samples using a low-field magnet (0.27 T). The hoof temperature was measured at the lateral side of the coronary band. A modified inversion recovery fast spin-echo (IR-FSE) sequence was used to measure the signal inte...
Daoualibi Y, Pereira AHB, Lima LR, Pool RR, Ubiali DG.Proliferative tenosynovitis (PT) is an inflammatory and proliferative disorder of the synovial membrane of the tendon sheath that is rare in animals. The histological alterations are characterized by multinodular neovascularization, with infiltration of histiocytic and multinucleated giant cells and haemosiderin deposition. We reviewed necropsy and biopsy records of horses submitted to the Setor de Anatomia Patológica of the Universidade Federal Rural do Rio de Janeiro from January 2017 to December 2020 to select cases of PT. We identified PT in three adult Brazilian Mangalarga Marchador hors...
Blair MJ, Gionfriddo JR, Polazzi LM, Sojka JE, Pfaff AM, Bingaman DP.To evaluate the feasibility of using a subconjunctivally implanted micro-osmotic pump for continuous delivery of medication to the eyes of horses- during a 7-day period. Methods: 4 healthy adult horses. Methods: With horses restrained in a standing position, micro-osmotic pumps were implanted subconjunctivally in each eye for 7 days. The treatment eye received an atropine-loaded micro-osmotic pump (100 microl of 1.5% atropine), and the contralateral eye received a sterile saline-loaded pump (100 microl of 0.9% NaCl) as a control treatment. Pupil size was measured at 12-hour intervals until val...
Kalpokas I, Martínez MN, Cavestany D, Perdigón F, Mattos RC, Meikle A.We investigated the early effects of the equine embryo on maternal serum concentrations of insulin-like growth factor 1 (IGF1), leptin and adiponectin, uterine immune cells and genes and proteins related to embryo development and the maintenance of pregnancy. Ipsilateral endometrial expression was assessed on Days 7 and 13 after ovulation for the following transcripts: oestrogen receptor ERα (ESR1), progesterone receptor (PGR), progestin and adipoQ receptor family member 5 (PAQR5), oxytocin receptor (OXTR), prostaglandin-endoperoxide synthase 2 (PTGS2), raf-1 proto-oncogene serine/threonine k...
Page AE, Adam E, Stewart JC, Gonzales C, Barker V, Horohov DW.While the use of lipopolysaccharide (LPS) to induce inflammation has been well described in the horse, the object of this study was to evaluate the effect of repeated intra-articular LPS injections and determine whether this method may be of use to assess changes in gene expression related to inflammation. Six mixed breed horses were utilized for this study, with three horses aged 10-17 years (older group) and three horses aged 3 years (younger group). One milliliter of phosphate-buffered saline containing 3 μg of LPS from Escherichia coli O111:B4 was aseptically injected into either the radi...
Seide RK, Kehoe JM.Studies of the molecular biology of lymphoid cells have markedly increased our understanding of how millions of different antibodies can be synthesized by a single animal. To date, the most detailed understanding has been achieved for the mouse, primarily because of the relatively greater experimental availability of this species. These studies, as well as those involving other species, have shown that the complete genes for antibody polypeptide chains are assembled from disparate genetic elements which are originally widely separated in the genome. The assembly process itself, together with t...
Gandini M.To compare 3 dorsal techniques for arthrocentesis of the distal interphalangeal joint in horses with regard to ease of performing the technique and to determine the role of operator experience in ease of performing these techniques. Methods: Observational study. Sample Population-Forelimbs from 17 equine cadavers and 12 horses (16 joints) undergoing arthrocentesis for therapeutic or diagnostic purposes. Methods: In both forelimbs from 7 of the equine cadavers, 3 arthrocentesis techniques (dorsal perpendicular, dorsolateral, and dorsal inclined) were performed in random order by a single experi...
Garcia P, Paris AC, Leufroy A, Popot MA, Bonnaire Y.A quantitative method, using LC/ESI-MS(n) with a quadrupole linear ion trap mass analyzer, has been developed for the analysis of ipratropium cation in horse plasma and urine. The method applies solid-phase extraction with WCX cartridges for plasma and MM2 cartridges for urine, prior to analysis by LC/ESI-MS(n). The efficiency of extraction combined with the sensitivity and the selectivity of MS(n) allows for the quantification of ipratropium cation at picogram per milliliter levels. The analytical capabilities of the method have been successfully checked by the quantitative analysis of ipratr...
Amann JF, Smith RM, Ganjam VK, Paull WK, McClure RC, Green EM, Garner HE.The distribution of cells that stain positive for beta-endorphin and ACTH immunoreactivity was studied in the pars intermedia (PI) of the hypophysis in 3 healthy horses and 2 healthy ponies. Serial sections treated with commercial antibodies generated against beta-endorphin or ACTH were processed for immunocytochemical studies, using the avidin biotin immunoperoxidase-complex method. Distribution patterns of cells reacting with antibodies were similar in cells from all equids. Cells immunostained for ACTH were numerous and widely distributed in the PI. Cells immunopositive for ACTH probably co...
Aguilera-Tejéro E, Pascoe JR, Woliner MJ.Effects of phenylbutazone (PBZ) and furosemide (FUR) on the respiratory tract of horses were evaluated, focusing on bronchial responsiveness. Four healthy Thoroughbreds were used and data were analyzed by use of a Latin square design. Histamine provocation tests (0.5, 1, 2, and 4 micrograms/min, i.v.) were done: (1) without prior treatment with PBZ or FUR, (2) 30 minutes after administration of PBZ (8 mg/kg, i.v.), (3) 1 hour after administration of FUR (1 mg/kg, i.v.), and (4) after administration of PBZ plus FUR. Pulmonary function tests (dynamic compliance, resistance, respiratory frequency...
DiPietro JA, Paul A, Todd KS.Forty horses from a herd known to have benzimidazole-resistant small strongyles were treated with mebendazole (8.8 mg/kg) or combinations of mebendazole and piperazine monohydrochloride (25, 40, or 55 mg of piperazine base/kg). Pretreatment and 7-day posttreatment fecal examinations were done. Fecal cultures and strongyle egg per gram (epg) counts, and in vitro testing for benzimidazole resistance were performed. Results of fecal examinations prior to treatment were similar in all horses, and results of testing were positive for benzimidazole resistance. Horses treated with mebendazole and pip...
Labruna MB, Amaku M.The present study evaluated the engorgement and drop-off rhythms of Anocentor nitens females feeding on horses. Drop-off rhythm was evaluated at 6h-intervals (06:00, 12:00, 18:00, and 00:00 h) on horses held in stalls or in a pasture. A new method of marking feeding female ticks (the bowknot technique) was developed to evaluate ticks on horses in pasture that attached to different parts of the horse's body. This technique was highly successful, indicating no significant interference on tick engorgement rate or final tick weight, length and reproductive capability. Horses held in the pasture du...
Kingsbury PA, Reid JF.Oxfendazole was administered in paste or drench formulations to groups of five horses carrying naturally acquired worm burdens. At a dose rate of 10 mg/kg the efficacy of either formulation appeared similar. One hundred per cent of the adult populations of the following genera was removed: Parascaris, Oxyuris, Strongylus (S edentatus, S vulgaris), Triodontophorus and Trichostrongylus axei. Efficacy against adult small strongyles, adult Habronema microstoma and immature Oxyuris equi was in the region of 96 to 99 per cent. The level of efficacy against immature small strongyles was at least 74 t...
Cunningham FM, Andrews M, Landoni MF, Lees P.Calcium ionophore A23187 induced time and concentration dependent production of immunoreactive leukotriene (LT) B4 by equine heparinized whole blood in vitro. Time dependent production of immunoreactive LTB4 by equine neutrophils and immunoreactive LTC4 by equine eosinophils in vitro was also demonstrated. The 5-lipoxygenase activating protein (FLAP) inhibitors, BAY X 1005 and BAY Y 1015, produced concentration dependent inhibition of ionophore-induced LTB4 synthesis by equine whole blood (mean +/- SEM IC50s n = 5; 6.14 +/- 0.28 microM vs. 12.30 +/- 0.75 microM for BAY Y 1015 and BAY X 1005, r...
Werners A, Karasek I, Butler C, Yeatts J, Enomoto H, Baynes R.Several different tick species are known to infest horses. Aside from causing serious health and welfare issues, including anaemia, ill thrift, and immunosuppression, ticks can transmit a variety of important, sometimes zoonotic, pathogens. The successful prevention and treatment of tick infestations have been described, but the information is scarce and, in many instances, anecdotal. Here we describe a practical and affordable prevention of tick infestation by using abamectin-impregnated cattle ear tags affixed to a safety collar. We have assessed the radial distribution of abamectin by analy...
Charlton C, Tulleners E.Two male racehorses (1 Standardbred, 1 Thoroughbred) were examined because of intraluminal cervical tracheal lesions, located 60 to 70 cm from the nares. A contact neodymium:yttrium aluminum garnet laser with a chisel probe attached to the fiber end was used to transendoscopically debride a nonhealing tracheal ulcer and to excise a pyogranulomatous mass. In both horses, the surgical sites healed quickly and the lesions did not redevelop.
Tomizawa N, Nishimura R, Sasaki N, Kadosawa T, Senba H, Hara S, Takeuchi A.Cervical myelography and survey radiography was performed on 12 light breed wobbling foals and a new radiographic measurement method was applied for more accurate diagnosis of cervical vertebral instability. Ratios of stenosis of the spinal canal on survey radiography and myelography using relative values in an individual foal were defined on radiograms of lateral flexed position of mid-cervical region, and coincidence between the ratios and histopathological lesions in the cervical spinal cord was investigated. Five of 6 foals had ratios of stenosis on myelography more than 40% at the interve...
Easter JL, Hague BA, Brumbaugh GW, Nguyen J, Chaffin MK, Honnas CM, Kemper DL.To evaluate the effect of peritoneal lavage on pharmacokinetics of gentamicin sulfate in healthy horses after experimental celiotomy. Methods: 13 clinically normal horses. Methods: Horses were randomly assigned to control or experimental groups. All horses received gentamicin (6.6 mg/kg of body weight, IV, q 24 h) before surgery, underwent experimental abdominal surgery, and had abdominal drains placed percutaneously. Horses of the experimental group received postoperative peritoneal lavage; horses of the control group did not receive peritoneal lavage. The day after surgery, 24 hours after th...
Ludewig T.The purpose of the study was to give a histological picture of the different skin regions of the mammary gland in mares. Special emphasis on the dark coating in the sulcus intermammarius was given. As a result, the dark pigmented udder skin can be subdivided into the skin of the Corpus mammae, the sulcus intermammarius and the teat skin. In the sulcus intermammarius the whole epidermis was considerably thicker than usual, especially the stratum corneum (up to 70 layers of cornified layers) and the stratum spinosum. In general, the squamous keratinocytes were unusually large. The histological p...
Duckworth DH, Madison JB, Calderwood-Mays M, Souba WW.Glutamine has been shown to be an important metabolic substrate of enterocytes in many animals, including cats, dogs, hamsters, human beings, monkeys, rabbits, rats, and sheep. To determine whether glutamine is important in the metabolism of cells of the equine gastrointestinal tract, we examined transintestinal differences in glutamine concentrations in the arterial and venous circulation, and measured activity of the major glutamine catabolizing enzyme, glutaminase. Arteriovenous differences provide an index of the amount of a given substrate removed by the tissue across which the measuremen...
Martínez-Boví R, Cuervo-Arango J.The objectives were to determine: (i) whether intrafollicular administration of PGE2 and PGF2α to mares would hasten follicle collapse and (ii) the differences in reproductive hormone characteristics in mares with spontaneous and prostaglandin-induced follicle collapses. Six mares were followed for two oestrous cycles each: when the mares reached a follicle diameter of 30-35 mm and showed mild-to-moderate endometrial oedema, mares were administered a single 0.5 ml dose containing 500 μg PGE2 and 125 μg PGF2α (treatment cycle) or a placebo (0.5 ml of water for injection; control cycle) into...
Dai CB, Xiao Y, Lu H, Shen RX, Shao YM.Membrane protein GP90 of China equine infectious anemia virus (EIAV) vaccine strain (DLV) and its parental wild type LN strain were expressed with Bac-to-Bac baculovirus expression system and BALB/c mice were inoculated with purified protein, thereby to explore the availability of protein for differential diagnosis and potential for preparing genetically engineered vaccine. Methods: The authors infected donkey PBMC culture with China EIAV vaccine strain (DLV) and its parental wild type LN strain, extracted its proviral DNA as template, amplified the GP90 of DLV and LN, respectively, and expres...
Sisodia CS, Kramer LL, Gupta VS, Lerner DJ, Taksas L.Pharmacological disposition of chloramphenicol was studied in horses. Minimum levels of the antibiotic (greater than or equal to 5 mu g/ml) in blood or plasma recommended to combat infections could not be achieved by 4.4 and 8.8 mg/kg I.V. or 30 and 50 mg/kg I.M. or 30 mg/kg oral (as palmitate salt) doses of chloramphenicol. Increasing the dose to 19.8 and 26.4 mg/kg I.V. provided such levels for about two and three hours respectively. A combination of 20 mg/kg I.V. and 30 mg/kg I.M. administered simultaneously did not provide more prolonged levels than 26.4 mg/kg I.V. alone. Chloramphenicol s...
Ducharme NG, Dill SG, Shin SJ, Schwark WS, Ducharme GR, Beilman WW.This preliminary study evaluated phenoxymethyl penicillin (Penicillin V) as an alternative to parenteral administration of penicillin in horses. Penicillin V was administered orally to five horses at two different doses and plasma levels of the drug were determined at timed intervals. The results were evaluated by regression analysis. Following the administration of penicillin V at a dose of 66,000 IU/kg or 110,000 IU/kg, the mean peak plasma levels obtained were 1.55 micrograms/mL and 2.34 micrograms/mL respectively. A plasma level two to four times above the minimal inhibitory concentration ...
Bristol DG, Cullen J.Six animals were used to compare simple interrupted, simple continuous, and stapled techniques for end-to-end rotated small colon anastomoses. Three ponies were evaluated three days after surgery for adhesion formation and luminal diameter at each anastomosis site. Two ponies and one horse were evaluated 14 days after surgery for adhesion formation. All anastomosis sites were examined histologically for alignment of tissue planes, and evidence of inflammation. No single technique was superior in all areas examined. While only three of the nine anastomoses had mild fibrinous adhesions at three ...
Murray RC, Gaughan EM, Debowes RM, Hoskinson JJ.To assess feasibility of insertion of 4.5-mm Herbert cannulated bone screws (HS) using fluoroscopic guidance and compare the mechanical shear strength of these HS and 4.5-mm AO cortical bone screws (AO) for fixation of dorsal plane slab osteotomies in equine cadaver third carpal bones (C3). Methods: Eight equine cadavers. Methods: Bone mineral composition and density of contralateral C3 were confirmed to be equivalent using dual-energy x-ray absorptiometry. A standard 10-mm C3 slab osteotomy was reduced using HS or AO instrumentation under fluoroscopic guidance. Specimens were loaded in shear ...
Thein P, Darai G, Janssen W, Bergle RD, Strube W, Floss G.From spring 1990 to summer 1991 we investigated 21 horses with clinical symptoms of EHV-infection by means of serological and virological methods including DNA-hybridization to identify the causative agents. The results indicated that, as already reported by us, EHV4 may also cause the paralytic form of the infection. The possibility of double infection with EHV4 and EHV1 cannot be excluded. In 3 out of 21 affected horses we could investigate brain tissue and/or spinal fluid by Dotblot hybridization with EHV1 and EHV4-DNA. The investigated samples of all three horses showed hybridization with ...
Bardell DA, Archer DC, Milner PI.Colic remains a life-threatening condition in the horse. Ischaemia and reperfusion following correction of small intestinal strangulation may produce oxidative stress. The ability to withstand oxidative stress depends on antioxidant levels and may be linked to horse survival. Objective: To measure peripheral antioxidant levels in horses undergoing exploratory laparotomy with small intestinal strangulation. Methods: Case-control study. Methods: Blood and plasma were collected from horses undergoing exploratory laparotomy for small intestinal strangulation and stored at -80°C. Controls involved...
Troedsson MH, Lee CS, Franklin RD, Crabo BG.The effect of seminal plasma on polymorphonuclear neutrophil (PMN) chemotaxis, PMN phagocytosis and complement-induced cytolysis was determined using blood plasma pooled from four horses and seminal plasma pooled from two stallions. To investigate chemotaxis, complement in blood plasma was activated with E. coli lipopolysaccharide in the presence of 0-50% seminal plasma diluted with a standardized volume of McCoy's medium and placed in a chemotactic chamber. Chemotaxis of blood derived equine PMNs toward the chemoattractants was determined after incubation at 37 degrees C for 45 min. To invest...
