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.
Meschter CL, Craig D, Hackett R.This investigation examines the histological and ultrastructural lesions of the colonic mucosa during terminal experimental infarction and subsequent reperfusion. Four ponies were anaesthetised and subjected to surgical torsion of the colon. Biopsies were collected at hourly intervals for 3 h, at which point the torsions were corrected. Circulation was re-established for 2 h and the bowel was re-biopsied at hourly intervals. The ponies were killed while under anaesthesia. During the 3 h experimental infarction, the bowel became macroscopically thickened and dark purple. Histologically, the muc...
Stanley S, Jeganathan A, Wood T, Henry P, Turner S, Woods WE, Green M, Tai HH, Watt D, Blake J.We have raised antibodies to morphine and etorphine and developed one-step enzyme-linked immunosorbent assays (ELISA) for these drugs as part of a panel of post race tests for drugs in racing horses. These tests are simple, can be completed in 2 h, and can be read by visual inspection. The morphine ELISA has an I50 for morphine of about 1.5 ng/mL, while the etorphine ELISA has an I50 for etorphine of 250 pg/mL. Cross-reactivity studies show that the antimorphine antibody cross-reacts well with levorphanol, hydromorphone, and oxycodone, while the anti-etorphine antibody showed no cross-reactivi...
Bristol DG, Riviere JE, Monteiro-Riviere NA, Bowman KF, Rogers RA.A model for the study of equine cutaneous physiology, pharmacology, and toxicology was developed. Four 4 x 12 cm and twenty-one 6 x 12 cm single-pedicle axial pattern skin flaps based on the caudal superficial epigastric artery, and eight 6 x 12 cm flaps based on the saphenous artery and medial saphenous vein, were raised and sutured in a tubed configuration. On day 2, each flap was removed, the artery was cannulated, and the flap was perfused with a modified Krebs-Ringer's albumin-based medium for at least 6 hours. Flap viability was assessed by glucose use, lactate production, and histologic...
Roelvink ME, Goossens L, Kalsbeek HC, Wensing T.The analgesic and spasmolytic effects of dipyrone (Novalgin) (2500 mg/100 kg bodyweight) hyoscine-N-butylbromide (Buscopan) (20 mg/100 kg bodyweight) and a combination of both drugs were evaluated in a balloon-induced model of colic, using five ponies with caecal fistulae. The drugs were given intravenously and 0.9 per cent sodium chloride solution (5 ml/100 kg bodyweight) was used as a control. The physiological saline solution and dipyrone had no effect on caecal contractions. After the injection of hyoscine-N-butylbromide and the drug combination caecal contractions ceased within 30 seconds...
Soave O, Brand CD.Coprophagy is performed by rodents and lagomorphs and to a lesser degree by piglets, foals, dogs and nonhuman primates. Due to the construction of the digestive system of rodents and rabbits, coprophagy is necessary to supply many essential nutrients. Bacterial synthesis of nutrients occurs in the lower gastrointestinal tract in these animals where little absorption is realized. The eating of their feces provides a method for obtaining these nutrients.
Heath TJ, Nikles SA.Secondary lymphoid nodules in lymph nodes of the horse are surrounded by a network of lymph sinuses, including the subcapsular sinus and its extensions around tabeculae, tubular and tubule-like sinuses deeper in the cortex, and sinuses between cord-like projections of cortical tissue. The precise role of this close association between sinuses and nodules in the transport of immune complexes, cells and cytokines is not known.
Willoughby RA, Ecker GL, McKee SL, Riddolls LJ.Mucociliary clearance rates from the trachea were determined in normal, sedated, diseased and exercised horses from scintigraphs obtained after an injection of technetium-99m sulphide colloid into the tracheal lumen. The group mean tracheal clearance rate of eight clinically normal horses during 42 trials was 2.06 +/- 0.38 cm/min. Significant between horse differences were found (p less than 0.05). When six and seven of these horses were given xylazine and detomidine hydrochloride, respectively, mean group tracheal clearance rates dropped significantly (p less than 0.05). The decreases from ea...
Prichard M, Ducharme NG, Wilkins PA, Erb HN, Butt M.We hypothesized that xanthine oxidase plays a role in the postischemic reperfusion injury in the equine small intestine. Under anesthesia, four horses and two ponies underwent ischemic strangulating obstructions of segments of the proximal jejunum, mid-jejunum and ileum. Prior to vascular occlusion, and at 1 h and 2 h of ischemia, full-thickness intestinal biopsies were collected for histopathological evaluation and for determination of combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone. The level of XO activity was expressed in percentage accordin...
Gasthuys F, De Moor A, Parmentier D.The influence of digoxin (0.01 mg/kg) given as an intravenous bolus followed by dopamine at different infusion rates (1.25, 2.5 and 5.0 micrograms/kg/min) on the cardiovascular depression during a standard halothane anaesthesia was studied in dorsally recumbent ventilated ponies. Preanaesthetic digitalization induced no clear positive cardiovascular effects over 30 minutes, except for non-significant increases in mean pulmonary artery pressure and total pulmonary resistance. These changes were probably time-related. No specific side-effects related to the fast intravenous digitalization were n...
Martinuk SD, Manning AW, Black WD, Murphy BD.The sialylation of eCG was examined to determine its influence on the in vivo metabolism and biological activity of the molecule. Sialic acid was decrementally removed from eCG by incubation with agarose-linked neuraminidase for varying time periods. Pharmacokinetic parameters for the disappearance of 4,000 IU (267 micrograms) of three desialylated eCG preparations (20%, 53%, and 80% sialic acid removed) and control eCG were determined in sheep. The clearance rate of eCG increased (p less than 0.05) with each decrement of sialic acid. The removal of 53% sialic acid enhanced the distribution of...
Weber JA, Freeman DA, Vanderwall DK, Woods GL.The hypothesis that treatment of pregnant mares with prostaglandin E2 (PGE2) hastens the oviductal transport of equine embryos was tested by treating bred mares with PGE2 on Day 3 after ovulation and subsequently measuring the rate of hastened oviductal transport (estimated by the uterine embryo recovery rate on Day 4 after ovulation). In a preliminary, noncontrolled experiment, oviductal transport was apparently not hastened after intramuscular, intrauterine, or intraperitoneal PGE2 administration to bred mares (0/6, 0/3, and 0/3 mares, respectively). Oviductal transport appeared to be hasten...
McDonnell SM, Pozor MA, Beech J, Sweeney RW.A 9-year-old atactic breeding stallion was trained to ejaculate, with only manual stimulation, while standing on the ground. Ejaculates obtained yielded fertile semen with morphologic and motility characteristics within the range for normal stallions. This method extended the breeding life of a stallion unable to mount a live or dummy mare or to ejaculate into an artificial vagina while standing on the ground.
Whitehair KJ, Parker JE, Smith GN, Adams SB, Bottoms GB.Serum levels of type III procollagen peptide (P-III-P) were measured by radioimmunoassay in clinically normal adult ponies (n = 15) and horses (n = 10). The mean serum levels of P-III-P from the ponies, 10.4 +/- 2.9 (SD) ng/mL, and the horses, 12.2 +/- 2.6 (SD) ng/mL, were not significantly different. Segments of jejunum were made ischemic to induce fibrous peritoneal adhesions in two ponies, and serum P-III-P levels were measured on days 4, 5, 7, 14, and 21. An exploratory celiotomy on day 21 revealed that the ischemic injury had induced fibrosis of the mesentery and bowel, but no adhesions h...
Stokes A, Corteyn AH, Murray PK.A group of three horses was experimentally infected with equine herpesvirus type 1 (EHV-1) and showed clinical signs characterised by a biphasic febrile response, leucopenia and cell associated viraemia accompanied by virus shedding from the nasopharynx. A second exposure to the virus 18 days later resulted in the isolation of virus from the nasopharynx of one horse. This and a further group of three EHV-1 seropositive horses were subsequently infected with equine herpesvirus type 4 (EHV-4) 147 days after the initial EHV-1 infection and virus was shed from the nasopharynx in the absence of cli...
Anderson GS, Belton P, Kleider N.Six horses severely affected by a seasonal dermatitis similar in both histopathology and epidemiology to Culicoides hypersensitivity (CH) and six unaffected or normal horses were inoculated intradermally with an extract of Culicoides obsoletus (Meigen), the most common Culicoides in southwestern British Columbia. Affected horses developed large welts within 20 min after injection, representing an immediate (type I) reaction; welts were largest 24 h or more after challenge, indicating in addition a delayed (type IV) reaction. This reaction was discernible for greater than 3 wk in some of the af...
Heap RB, Hamon MH, Allen WR.Aromatase distribution in membranes of preimplantation horse and donkey conceptuses was compared by measuring the incorporation of [3H]androstenedione into oestrone and oestradiol-17 beta. In the donkey conceptus, aromatase activity was similar in all the tissues examined (yolk sac, chorionic girdle and allantochorion), whereas in the horse it was generally lower and showed the relationship chorionic girdle greater than yolk sac greater than allantochorion. A higher proportion of labelled precursor was incorporated into oestradiol-17 beta by extra-embryonic tissues of the donkey compared with ...
Timofeev BA, Bolotin IM, Stepanova LP, Bogdanov AA, Georgiu Kh, Malyshev SN, Petrovskiĭ , Klibanov AL, Torchilin VP.The cultures of Nuttalia eque mainly develop in the reticuloendothelial organs and so in treatment of nuttaliosis in horses and the Nuttalia carriers diamidine, an analog of imidocarb or imidozoline, was used encapsulated in liposomes. The liposomes were prepared with a modification of the phase inversion method (the lipids were dissolved in a mixture of freon-11 and chloroform). The content of the organic solvents in the preparation, as evidenced by gas liquid chromatography, was less than 0.2 per cent. The main fraction consisted of particles 1.5 to 2.5 microns in diameter. The tests on anim...
Jean-François MJ, Poskitt DC, Turnbull SJ, Macdonald LM, Yasmeen D.We have developed an in vivo passive transfer assay using mice to identify monoclonal antibodies (mAbs) which offer protection against Streptococcus equi infection. The assay was developed using serum antibodies collected from horses convalescing from strangles. In this study, we show that a preparation of M-like protein, acid-extracted from S. equi, affords 80% protection to mice immunized with it. A number of mouse mAbs directed against a preparation of M-like protein were then assessed for their ability to passively protect mice against challenge with a lethal dose of the bacteria. Two mAbs...
Desideri A, Stefanini S, Polizio F, Petruzzelli R, Chiancone E.Apoferritin has been selectively labeled with a maleimide nitroxide derivative at Cys-126, located in the hydrophilic 3-fold channels. Titration of this derivative with Fe(II), which gives rise to the initial Fe(III)-apoferritin complex, produces, at low metal-to-protein ratios, a decrease of the intensity of the label EPR signal due to the occurrence of a magnetic dipolar interaction. A label-metal distance ranging between 8-12 A can be estimated from titrations performed with VO(IV), which is known to bind in the 3-fold channels, and likewise produces a decrease in the label EPR signal. The ...
Büchi S, Waelchli RO, Corboz L, Gygax AP, Wälti RJ.In the mare, natural breeding is associated with bacterial contamination of the reproductive tract. The purpose of this study was to examine postcoital bacterial contamination and the resulting inflammatory response of the uterus. Uterine swabs for bacteriological and cytological examination were obtained from 80 mares. Each mare was sampled once between 4 and 69 hours postbreeding. In mares which did not conceive, sampling was repeated at the following estrus. The findings were compared with those obtained prior to breeding and correlated with the breeding outcome. Bacteria were cultured from...
Chapman MR, Klei TR, French DD.A critical trial was performed with five ponies 6-9 months of age and raised on a horse farm with demonstrated benzimidazole-resistant cyathostomes. Eleven species of cyathostomes were recovered, seven of which had resistance to thiabendazole. Degrees of resistance varied among ponies and from species to species. Resistant species were Cyathostomum coronatum, Cyathostomum catinatum, Cylicostephanus minutus, Cylicostephanus calicatus, Cylicostephanus longibursatus, Cylicostephanus goldi and Cylicocylus nassatus. This is the first study identifying resistant cyathostome species in the Gulf Coast...
Gasthuys F, de Moor A, Parmentier D.The influence of different rates of dopamine and dobutamine on the cardiovascular depression during a standard halothane anesthesia was studied in dorsally recumbent ventilated ponies. Haemodynamic and respiratory responses were investigated by means of cardiac output (CO) determination (thermodilution technique), mean systemic (MAP) and pulmonary artery pressure (MPAP) (direct intravascular method) and arterial blood analysis (blood gases and packed cell volume). An important cardiopulmonary depression characterized by decreases (55% of the standing values) in CO, cardiac index (CI), MAP, MPA...
Alexandersen S, Carpenter S.The polymerase chain reaction was used to amplify and clone parts of the envelope gene and overlapping S3 open reading frame, thought to encode rev, of the virulent in vivo-derived Th-1 isolate of equine infectious anemia virus (EIAV). The results indicated that EIAV consists of a heterogeneous mixture of genotypes present at the first febrile cycle after initial infection. We showed that the Th-1 isolate apparently contains nondefective genotypes as well as types which have transmembrane protein truncations or are rev deficient. Furthermore, we could confirm the presence of a hypervariable re...
Sivula NJ.Between 1984 and 1989, 33 horses were diagnosed with renosplenic entrapment of the large colon. Duration of colic, signalment, physical findings, and laboratory values were determined, and treatment methods were evaluated. Nonsurgical correction was attempted in 22 of the horses with suspected renosplenic entrapment of the large colon and was successful in 11 cases. Survival and complication rates also were determined. Nonsurgical correction is a viable alternative to immediate surgery for renosplenic entrapment of the large colon, if cases are selected properly.
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.
Halldórsdóttir S, Lazary S, Gunnarsson E, Larsen HJ.Three hundred and three horses, exported from Iceland to Norway, Sweden, Denmark, Switzerland or Germany were tested for their distribution of leucocyte antigens. One hundred and thirty-six horses were affected with summer eczema. The panel of sera recognised the internationally accepted ELA-specificities A 1 to A10, and the nine work shop specificities W 11 to W 15 and W 18 to W 21. Also, some local specificities, characterised in Switzerland (Be I, Be III, Be 8, Be 25, Be 26, Be 27), and two non major histocompatibility complex (MHC)-linked antigens (Ely 1:1, Ely 2) were included. Only one a...
Carney NJ, Squires EL, Cook VM, Seidel GE, Jasko DJ.Donor mares of mixed, light-horse breeds, maintained at Colorado State University, provided 104 embryos for immediate transfer (fresh embryos). One hundred and thirty-six additional embryos were collected on various breeding farms in the United States and were shipped to Colorado State University via commercial airlines (cooled embryos). Embryos were harvested 7 d after ovulation, graded, and either transferred into a mare immediately (<1 h) or placed in Ham's F-10 medium plus 10% fetal calf serum in an atmosphere of 5% CO2, 5% O2, 90% N2 and packaged in a passive cooling unit (Equitai...
Madison JB, Hamir AN, Ehrlich HP, Haberman J, Topkis V, Villasin JV.Full-thickness skin wounds were created on the dorsum of both metacarpi in 8 horses. Three topical treatment regimens were studied. All wounds were bandaged with a nonadherent dressing, which was held in place with a snug elastic wrap. Group-A wounds were treated with a proprietary topical wound medication that consisted of a spray and an ointment. Group-B wounds were treated with the same regimen, except the putative active ingredients in the ointment were omitted. Group-C wounds were treated with a dry nonadherent bandage only. Wound dressings were changed every day and the limbs were photog...
Ganiev I, Alexandrova N, Aimaletdinov A, Rutland C, Malanyeva A, Rizvanov A, Zakirova E.One of the major problems observed in veterinary practice is articular cartilage injuries in animals. In terms of agriculture, it leads to their culling from the herd, even if they are highly productive animals. With companion animals, owners usually have to decide between euthanasia or long-term sometimes lifelong treatment of the injury by a veterinarian. The use of mesenchymal stem cells (MSCs) for the treatment of cartilage injury in veterinary medicine is based on the good results observed in preclinical studies, where large animals have been used as experimental models to study the regen...
Lescun TB, Hoffseth K, Yang HT, Hansma PK, Kopeikin HS, Chandrasekar S.To compare results obtained with a handheld reference point indentation instrument for bone material strength index (BMSi) measurements in the equine third metacarpal bone for various testing conditions. Methods: 24 third metacarpal bones. Methods: Third metacarpal bones from both forelimbs of 12 horses were obtained. The dorsal surface of each bone was divided into 6 testing regions. In vivo and ex vivo measurements of BMSi were obtained through the skin and on exposed bone, respectively, to determine effects of each testing condition. Difference plots were used to assess agreement between BM...
Pozor MA, Zambrano G, Roser J, Hess R, Runyon S, Runcan E, Thomas BF, Dymock D, Macpherson ML, Troedsson MH, Kelleman A.The objective of this study was to evaluate acute endocrine effects as well as histological changes in testicular parenchyma induced by the contraceptive compound RTI-4587-073(l). Six miniature stallions were used in this experiment. The treatment group (n = 3) received one oral dose of 12.5 mg/kg of RTI-4587-073(l), and the control group (n = 3) received placebo only. The stallions' baseline parameters (semen, testicular dimensions, endocrine values) were collected and recorded for 5 weeks before treatment and for 6 weeks after treatment. Multiple blood samples were collected for endoc...
Ho EN, Leung DK, Leung GN, Wan TS, Wong HN, Xu X, Yeung JH.Mesterolone (1alpha-methyl-5alpha-androstan-17beta-ol-3-one) is a synthetic anabolic androgenic steroid (AAS) with reported abuses in human sports. As for other AAS, mesterolone is also a potential doping agent in equine sports. Metabolic studies on mesterolone have been reported for humans, whereas little is known about its metabolic fate in horses. This paper describes the studies of both the in vitro and in vivo metabolism of mesterolone in racehorses with an objective to identify the most appropriate target metabolites for detecting mesterolone administration. In vitro biotransformation st...
Dobler D, Gerber M, Schmidts TM, Runkel F, Schlupp P.Human nail diseases, mostly caused by fungal infections, are common and difficult to treat. The development and testing of new drugs and drug delivery systems for the treatment of nail diseases is often limited by the lack of human nail material for permeation studies. Animal material is frequently used, but there are only few comparative data on the human nail plate, and there is neither a standardized test design nor a nail bed analogue to study drug uptake into the nail. In this study, a new permeation device was developed for permeation studies, and the permeation behavior of three model s...
Fowden AL, Silver M.Epostane, a competitive inhibitor of 3 beta-HSD was administered intravenously to a pregnant mare between 292 and 330 days of gestation at doses of 1-3 mg/kg/min. Plasma progesterone concentrations fell rapidly during epostane infusion in both the artery and uterine vein and remained significantly depressed for 4-5 h after the start of infusion. The venous arterial (V-A) plasma concentration difference in progesterone across the uterus also decreased significantly in response to epostane infusion. There were no significant changes in plasma progesterone or in the V-A concentration difference i...
Roberts MC, Seawright AA.Colic was induced in horses and ponies following topical or intravenous (iv) administration of amitraz, a formamidine acaricide. The condition was characterised by rapid cessation of intestinal sounds, stasis, extensive impaction and tympany throughout the large colon. Three animals that were necropsied had a faecalith obstructing the proximal small colon aboral to marked colonic impaction. A reproducible and reversible impaction colic syndrome could be induced by an iv injection of 1 mg amitraz/kg body weight in solvent. There were immediate central nervous system and intestinal signs. Large ...
Slocombe RF, Todhunter RJ, Stick JA.A qualitative and quantitative study was made of 2 adult horses to determine the effect of specimen preparation and the influence of anatomically separate regions on the microscopic structure of the esophagus. The effects of 3 fixative solutions (formalin, Bouin's fixative and Karnovsky's fixative) and 4 histologic staining procedures (hematoxylin and eosin, Gomori's trichrome, Laidlow's reticulum, and orcein-elastin) were compared. Density-dependent image analysis was used to compare the relative contributions of elastic and reticular fibers in esophageal connective tissue for each region. Cr...
Guan F, Robinson MA, Soma LR.Etanercept is a protein-based medication for the treatment of human patients with rheumatoid arthritis and other autoimmune-based diseases; its pharmacological action is to inhibit and antagonize tumour necrosis factor alpha. Etanercept was rumoured to be used in horse racing in North America. To detect such use, the aim of this study was to develop a liquid chromatography-mass spectrometry (LC-MS) method for confirmation of etanercept in equine plasma. Etanercept was extracted from plasma by anti-human IgG antibody linked to magnetic beads. The analyte was reduced and alkylated, and then dige...
Boeckh S, Buchanan C, Boeckh A, Wilkie S, Davis C, Buchanan T, Boothe D.Following approval of a concentrated injectable formulation of enrofloxacin for cattle (Baytril 100 Injectable, Bayer Corp. Agricultural Division, Shawnee Mission, KS), equine practitioners have started administering this preparation both parenterally and orally to horses, despite the lack of pharmacokinetic data in this species. Six healthy horses received enrofloxacin at 7.5 mg/kg both orally and intravenously, with the sequence being randomly assigned and at least 1 week of washout allowed between administrations. Blood samples were collected from each horse at various intervals after drug ...
Van Der Vekens N, van Dievoet MA, De Puydt H, Decloedt A, Ven S, De Clercq D, Deprez P, van Loon G.Although cardiac troponin T (cTnT) assays have been used to detect myocardial damage in horses, a cTnT assay has not been analytically validated, to our knowledge. The aims of this study were to estimate the precision of a high-sensitivity cTnT assay in horses and determine the effect of hemolysis on the measured cTnT concentration. Serum samples from horses were mixed in 3 different pools. Pool 1 consisted of samples from 3 healthy horses, pool 2 from 6 horses with heart failure or atypical myopathy, and pool 3 from 10 horses with atypical myopathy. The within- and between-run coefficients of...
Tendillo FJ, Mascías A, Santos M, López-Sanromán J, De Rossi R, San Román F, Gómez de Segura IA.To determine the minimum alveolar concentration (MAC) of desflurane (DES) in the horse. Methods: Prospective study. Methods: Six healthy adult horses (three males and three females) weighing 370 +/- 16 kg and aged 9 +/- 2 years old. Methods: Anesthesia was induced with DES vaporized in oxygen via a face mask connected to a large-animal, semiclosed anesthetic circle system. The horses were endotracheally intubated and positioned in right lateral recumbency. Inspired and end-tidal DES were monitored using a calibrated Ohmeda RGM 5250 multigas analyzer (Ohmeda-BOC, Spain). The MAC of desflurane t...
Bentley E, Murphy CJ.A thermal cautery technique was used to treat spontaneous chronic corneal epithelial defects (SCCEDs) in 9 eyes of 8 dogs and 2 eyes of 2 horses. Animals were sedated, and a topical anesthetic was applied. A handheld thermal cautery unit was then used to make multiple, small (< or = 1 mm in diameter), superficial burns throughout the affected area. The cautery unit was applied just until the slightest degree of contraction of the collagen fibrils was observed. After the stromal bed of the defect was treated, a rim of epithelium that extended approximately 1 mm around the denuded stroma was ...
Miller SM, Stover SM, Taylor KT, Zarucco LA.A technique was developed for arthrocentesis of the palmaroproximal pouch of the pastern joint. The landmark for percutaneous puncture is a 'V' shaped depression formed by the palmar aspect of the proximal phalanx (P1) dorsally, an eminence associated with the attachment of the collateral ligaments to P1 and the middle phalanx distally and the insertion of the lateral branch of the superficial digital flexor tendon palmarodistally. Comparison of arthrocentesis between the palmaroproximal approach and the traditional dorsal approach in 8 cadavers and 8 horses demonstrated that the palmaroproxim...
Bastos HB, Kretzmann NA, Santos GO, Esmeraldino AT, Rechsteiner SF, Mattos RC, Neves AP.The period from the emergence of a dominant follicle until its formation requires tissue remodeling. Enzymes promoting collagen lysis, such as matrix metalloproteinases (MMPs), are fundamental for the process of extracellular matrix remodeling, which allows changes in ovarian tissue architecture during follicular growth. It has been suggested that the production of these enzymes may be affected by the rise in circulating concentrations of LH, which acts on the ovarian surface epithelium (OSE). The aim of this study was to determine the expression of MMP-1, MMP-2, and LH receptor (LHR) in the o...
Klohnen A, Wilson DG, Hendrickson DA, Cooley AJ, MacWilliams PS.To evaluate the bactericidal properties of chlorhexidine diacetate (CHD) after potentiation with EDTA and Tris buffer (EDTA-Tris), and to find a potentiated CHD concentration that would achieve 90 to 100% killing for all bacteria tested. Methods: 6 adult ponies. Methods: Serial dilutions of CHD, CHD in EDTA-Tris and EDTA-Tris alone were evaluated for bactericidal activity against Staphylococcus aureus, Escherichia coli, and Streptococcus zooepidemicus. The tarsocrural joints of 6 ponies were lavaged with either 1 L phosphate-buffered saline solution (control) or 1 L of 0.0005% CHD in EDTA-Tris...
Temple-Wong MM, Raleigh AR, Frisbie DD, Sah RL, McIlwraith CW.To assess whether the combination of hyaluronan, sodium chondroitin sulfate, and -acetyl-d-glucosamine (HCSG) lubricates articular cartilage in vitro and modulates joint lubrication in vivo. Methods: 16 healthy adult horses. Methods: The effects of HCSG injections on SF lubricant properties and joint health, immediately after injury and 2 weeks later, were analyzed by use an equine osteochondral fracture model of post-traumatic osteoarthritis (OA). Middle carpal joints of adult horses were randomly assigned to 1 of 4 surgical treatment groups as follows: normal nonsurgical group (n = 8), norma...
Wilson DV, Patterson JS, Stick JA, Provost PJ.The role of platelet-activating factor (PAF) in mediating the colonic damage that develops after large-colon torsion was studied in 14 ponies. Morphologic changes in areas of the ascending colon and selected abdominal and thoracic viscera after 1 hour of large-colon torsion and 3 to 5 hours of reperfusion were determined, as well as the protective effects of systemic administration of a specific PAF antagonist (WEB 2086). Ponies were selected then allocated at random and in equal numbers to 2 groups that received 1 of 2 treatments prior to induction of large-colon torsion: group 1--control (sa...
Simmons EJ, Bertone AL, Hardy J, Weisbrode SE.To quantitate nitric oxide synthase (NOS) activity in healthy and interleukin 1beta (IL-1beta)-exposed equine synovial membrane. Methods: 6 healthy horses, 2 to 8 years old. Methods: Recombinant human IL-1beta (0.35 ng/kg of body weight) was injected intra-articularly into 1 metacarpophalangeal joint of each horse. The contralateral joint served as an unexposed control. All horses were euthanatized 6 hours after injection of IL-1beta, and synovial membrane specimens were assayed for NOS activity by measuring conversion of arginine to citrulline. Severity of inflammation was semiquantitated by ...
Orsini JA, Park MI, Spencer PA.Concentrations of amikacin in endometrial tissue and plasma were studied in mares in estrus after intrauterine infusion of 1.0 or 2.0 g once a day for 3 consecutive d, and after 9.7 or 14.5 mg/kg body weight (BW) had been injected intramuscularly once a day for 3 consecutive d to determine concentrations of amikacin sulfate in plasma and endometrial tissues, and whether parenteral administration provides any advantages over intramuscular infusion. No amikacin was detected in serum at the 1.0 g dose. At the infusion dose of 2.0 g once a day, very low levels of serum amikacin were detected at 1 ...
Hagen J, Brouwer J, Lux S, Weiske F, Jung FT.The aim of the current in vivo, observational study was to investigate the effects of different hoof manipulations on landing duration (LandD), location (IC) and angle of initial contact (IC) in the front feet of horses. A novel, hoof-mounted, inertial measurement unit sensor system (IMU) was used. Ten sound, crossbred horses were fitted with an IMU sensor at the dorsal hoof wall and examined barefoot and after trimming. Additionally, the application of 120 g lateral weights and 5° medial side wedges as well as steel, aluminium, egg bar, and lateral extension shoes were tested. Horses were gu...
Stang FL, Bjerregaard R, Müller CE, Ergon Å, Halling M, Thorringer NW, Kidane A, Jensen RB.Carbohydrates in forages constitute an important part of the feed ration for all horses. The aim of the present study was to investigate the effect of harvest time on carbohydrate composition and digestion of various grass species. The experiment was divided into three parts 1) characterization of the chemical composition of experimental feeds (6 grass species: meadow fescue [MF], cocksfoot [CF], perennial ryegrass [PR], smooth bromegrass [SB], tall fescue [TF], and timothy [TI], and 3 harvest times: early, medium, and late first cut), 2) measurements of the in vitro digestion of selected expe...
Kong N, Yi R, Zhao S, Sandhu J, Lam G, Loganathan D, Morrissey B.A sensitive hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry method was developed and validated for the simultaneous detection and quantification of etilefrine and oxilofrine in equine blood plasma and urine. The method is highly sensitive and specific with good precision and accuracy. In plasma the limit of detection and limit of quantification are 0.03 and 0.1 ng/mL, respectively, for both analytes. In urine the limit of detection and limit of quantification are 0.3 and 1 ng/mL, respectively, for both analytes. The suitability of the method for doping con...
Dirikolu L, Lehner AF, Harkins JD, Woods WE, Karpiesiuk W, Gates RS, Fisher M, Tobin T.Pyrilamine is an antihistamine used in human and veterinary medicine. As antihistamines produce central nervous system effects in horses, pyrilamine has the potential to affect the performance of racehorses. In the present study, O-desmethylpyrilamine (O-DMP) was observed to be the predominant equine urinary metabolite of pyrilamine. After intravenous (i.v.) administration of pyrilamine (300 mg/horse), serum pyrilamine concentrations declined from about 280 ng/mL at 5 min postdose to about 2.5 ng/mL at 8 h postdose. After oral administration of pyrilamine (300 mg/horse), serum concentrations p...
Labeda DP, Price NP, Kroppenstedt RM, Donahue JM, Williams NM, Sells SF.Two actinomycete strains, NRRL B-24165(T) and NRRL B-24166(T), isolated from lesions on equine placentas in Kentucky, USA, were analysed using a polyphasic taxonomic approach. On the basis of phylogenetic analysis of 16S rRNA gene sequences, morphological observations and the presence of ll-diaminopimelic acid as the diagnostic diamino acid in whole-cell hydrolysates, the new isolates clearly belonged to the genus Streptomyces. Analyses of the phylogenetic positions of strains NRRL B-24165(T) and NRRL B-24166(T) based on 16S rRNA gene sequences of all recognized species of the genus Streptomyc...
Ramsay JD, Evanoff R, Mealey RH.Hepacivirus A (also known as nonprimate hepacivirus and equine hepacivirus) is a hepatotropic virus that can cause both transient and persistent infections in horses. The evolution of intrahost viral populations (quasispecies) has not been studied in detail for hepacivirus A, and its roles in immune evasion and persistence are unknown. To address these knowledge gaps, we first evaluated the envelope gene (E1 and E2) diversity of two different hepacivirus A strains (WSU and CU) in longitudinal blood samples from experimentally infected adult horses, juvenile horses (foals), and foals with sever...
Endo Y, Hobo S, Korosue K, Ootsuka K, Kitauchi A, Kikkawa R, Hidaka Y, Hagio M, Tsuzuki N.The present study evaluated the effects of single-dose filgrastim on hematology in 16 healthy horses after long-distance transportation. Horses were assigned to receive filgrastim (0.23 µg/kg, SC, once; G-CSF group; n=8) or saline (0.9% NaCl) solution (0.3 ml, SC, once; control group; n=8) ≤ 1 hr before transportation. Horses were transported 2,530 km using commercial vans over the course of approximately 44 hr. Clinical examinations and hematologic analyses were performed on all horses before and after transportation. Because the post-transportation white blood cell counts and bacillary ne...
Guzeloglu A, Atli MO, Kurar E, Kayis SA, Handler J, Semacan A, Aslan S.The aims of the present study were to elucidate the expression profiles of leukotriene (LT) pathway mRNA transcription and to determine the possible interaction of LT and prostaglandin (PTG) pathways genes in equine endometrium during the estrous cycle and early pregnancy. Endometrial biopsies were obtained from mares on the day of ovulation (d0), at late diestrous (LD, n = 4), and after luteolysis in the estrus phase (AL, n = 4) of the cycle. Biopsies were also taken on Days 14 (P14; n = 4), 18 (P18, n = 4), and 22 (P22, n = 4) during early pregnancy that were comparable days to cyclic sampli...
Anderson K, Morrice-West AV, Walmsley EA, Fisher AD, Whitton RC, Hitchens PL.Musculoskeletal injuries are observed in Thoroughbred racehorses and may become catastrophic. Currently, there are limited methods for early detection of such injuries. Most injuries develop gradually due to accumulated damage, providing the opportunity for early detection. Horses experiencing pain or lameness may exhibit changes in behaviour so the development of an objective, real-time system monitoring horse behaviour may enable detection of bone injuries before catastrophic failure. Objective: To determine whether intensive observational methods of assessing horse behaviour can be replaced...
Benamou AE, Marlin DJ, Lekeux P.Based on previous in vitro studies, we hypothesised that endothelin (ET) would induce vasoconstriction in the pulmonary circululation of the horse and that this action would be mediated via ET(A) receptors. Pulmonary and systemic haemodynamic responses to endothelin-1 (ET-1), a potent vasoactive endogenous peptide, were investigated in 6 conscious, nonsedated horses at rest. Bolus i.v. injections of exogenous ET-1 (0.1, 0.2 and 0.4 microg/kg bwt) caused significant increases in pulmonary (PAP) and carotid (CAP) artery pressures, with peak increases of 79% and 51% for mean PAP and CAP, respecti...
