The topic of drugs and horses encompasses the study of various pharmacological agents used in equine medicine for therapeutic purposes. This includes the administration of medications for pain management, disease treatment, and performance enhancement. The pharmacokinetics and pharmacodynamics of drugs in horses are key areas of research, as they determine the absorption, distribution, metabolism, and excretion of these substances. Additionally, the topic covers the detection and regulation of substances in competitive equestrian sports to ensure fair play and animal welfare. This page compiles peer-reviewed research studies and scholarly articles that explore the effects, safety, and regulatory aspects of drug use in equine health and performance.
Luo QH, Chen ML, Chen ZL, Huang C, Cheng AC, Fang J, Tang L, Geng Y.The aminolycoside Gentamicin is a widely used antibiotic, applied in equine medicine. Despite its clinical use, concerns remain regarding the potential toxic side-effects, such as nephrotoxicity. Early detection of renal damage is critical in preclinical drug development. This study was aimed to determine whether kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) may be early indicators in the assessment of Gentamycin-induced nephrotoxicity. Methods: In our study, a model of Gentamicin-induced nephrotoxicity in male Sprague Dawley rats treated for up to 7 da...
Younkin TJ, Davis EG, Kukanich B.The primary study objective was to compare the pharmacokinetics of p.o. terbinafine alone to p.o. terbinafine administered with p.o. cimetidine in healthy adult horses. The second objective was to assess the pharmacokinetics of terbinafine when administered per rectum in two different suspensions at 30Â mg/kg to adult horses. Six healthy adult horses were included in this crossover study. Plasma terbinafine concentrations were quantified with liquid chromatography and mass spectrometry. The half-life (geometric mean) was 8.38 and 10.76Â h, for p.o. alone and p.o. with cimetidine, respectively....
Di Salvo A, Busechian S, Zappulla F, Marchesi MC, Pieramati C, Orvieto S, Boveri M, Predieri PG, Rueca F, Della Rocca G.A new formulation of omeprazole in gastro-resistant granules was tested with regard to its pharmacokinetics and tolerability. Twenty-four horses were randomly divided into three groups (8 horses/group) and treated, according a parallel study design, as follows: Group A untreated (control group), Group B received 4Â mg/kg of omeprazole, and Group C received 12Â mg/kg of omeprazole, both of which were treated orally once a day for 90Â days. Blood samples, taken from Group B subjects during the 1st and the 29th day of treatment at pre-established time points, were used to determine the concentrat...
Wong KS, Chan GHM, Ho ENM, Wan TSM.Growth hormone (GH), or somatotropin, is a protein that may enhance physical performance and facilitate growth and wound healing. For this reason, growth hormones and their recombinant analogues are prohibited in human sports by the World Anti-Doping Agency (WADA) and in horseracing under Article 6 of the International Agreement on Breeding, Racing and Wagering published by the International Federation of Horse Racing Authorities (IFHA). Identifying the illicit use of GHs in both human athletes and racehorses is challenging, especially when differentiating between endogenous and exogenous GHs,...
Waller CC, McLeod MD.In recent years, the potential for anabolic steroid abuse in equine sports has increased due to the growing availability of designer steroids. These compounds are readily accessible online in 'dietary' or 'nutritional' supplements and contain steroidal compounds which have never been tested or approved as veterinary agents. They typically have unusual structures or substitution and as a result may pass undetected through current anti-doping screening protocols, making them a significant concern for the integrity of the industry. Despite considerable focus in human sports, until recently there ...
Steffey EP, Pascoe PJ.To quantitate the dose- and time-related magnitude of the anesthetic sparing effect of, and selected physiological responses to detomidine during isoflurane anesthesia in horses. Methods: Randomized cross-over study. Methods: Three, healthy, young adult horses weighing 485 ± 14 kg. Methods: Horses were anesthetized on two occasions to determine the minimum alveolar concentration (MAC) of isoflurane in O and then to measure the anesthetic sparing effect (time-related MAC reduction) following IV detomidine (0.03 and 0.06 mg kg). Selected common measures of cardiopulmonary function, blood glucos...
Ramsay EC, Geiser D, Carter W, Tobin T.To compare the effect of orally delivered detomidine on head posture when administered alone or in combination with two different food items, and to determine the serum concentrations of detomidine after oral delivery. Methods: Prospective randomized experimental study. Methods: Fifteen adult grade mares weighing 328-537 kg. Methods: The horses were randomly assigned to one of the three treatment groups (five horses each). The groups were given detomidine (0.06 mg kg): alone; mixed with 3 mL of an apple sauce and gum mixture; or mixed with 3 mL molasses. Head droop, measured before treatment a...
Wagner AE, Mama KR, Steffey EP, Brevard LF, Hellyer PW.To compare behavioral characteristics of induction and recovery in horses anesthetized with eight anesthetic drug protocols. Methods: Randomized prospective experimental study. Methods: Eight horses, 5.5 ± 2.4 years (mean ± SD) of age, and weighing 505 ± 31 kg. Methods: After xylazine pre-medication, each of eight horses was anesthetized on four occasions using one of eight different anesthetic induction protocols which incorporated various combinations of ketamine (KET), propofol (PRO), and thiopental (THIO): THIO 8 mg kg; THIO 6 mg kg + PRO 0.5 mg kg; THIO 4 mg kg + PRO 1 mg kg; THIO 2 mg...
Salomonsson ML, Bondesson U, Hedeland M.This paper describes quantitative methods for the determination of dimethylsulfoxide (DMSO) in equine plasma and urine based on simple precipitation and dilution followed by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry (HILIC-MS/MS). DMSO is a polar solvent with analgesic and anti-inflammatory properties. Its pharmacological features make it prohibited in horse racing. However, since DMSO is naturally present in the horses' environment, international threshold values have been implemented for plasma and urine (1 and 15 µg/mL, respectively). Previously pr...
Burkett BN, Thomason JM, Hurdle HM, Wills RW, Fontenot RL.Determine the effects of nonsteroidal anti-inflammatory drugs (NSAID) on platelet function and thromboxane synthesis immediately after drug administration and following 5 days of NSAID administration in healthy horses. Methods: Randomized cross-over study. Methods: Healthy adult horses (n=9; 6 geldings and 3 mares). Methods: Horses received either flunixin meglumine (1.1 mg/kg IV every 12 hours), phenylbutazone (2.2 mg/kg IV every 12 hours), or firocoxib (loading dose of 0.27 mg/kg IV on day 1, then 0.09 mg/kg IV every 24 hours for 4 days) for a total of 5 days. Blood samples were collected pr...
Ojo KK, Dangoudoubiyam S, Verma SK, Scheele S, DeRocher AE, Yeargan M, Choi R, Smith TR, Rivas KL, Hulverson MA, Barrett LK, Fan E, Maly DJ....Sarcocystis neurona is the most frequent cause of equine protozoal myeloencephalitis, a debilitating neurological disease of horses that can be difficult to treat. We identified SnCDPK1, the S. neurona homologue of calcium-dependent protein kinase 1 (CDPK1), a validated drug target in Toxoplasma gondii. SnCDPK1 shares the glycine "gatekeeper" residue of the well-characterized T. gondii enzyme, which allows the latter to be targeted by bumped kinase inhibitors. This study presents detailed molecular and phenotypic evidence that SnCDPK1 can be targeted for rational drug development. Recombinant ...
Wong ASY, Leung GNW, Leung DKK, Wan TSM.Anabolic steroids are banned substances in equine sports. Gas chromatography-mass spectrometry (GC-MS) has been the traditional technique for doping control analysis of anabolic steroids in biological samples. Although liquid chromatography-mass spectrometry (LC/MS) has become an important technique in doping control, the detection of saturated hydroxysteroids by LC-MS remains a problem due to their low ionization efficiency under electrospray. The recent development in fast-scanning gas-chromatography-triple-quadrupole mass spectrometry (GC-MS/MS) has provided a better alternative with a sign...
Welsh CE, Parkin TDH, Marshall JF.As antimicrobial resistant bacterial strains continue to emerge and spread in human and animal populations, understanding prescription practices is key in benchmarking current performance and setting goals. Antimicrobial prescription (AP) in companion veterinary species is widespread, but is neither monitored nor restricted in the USA and Canada. The veterinary use of certain antimicrobial classes is discouraged in some countries, in the hope of preserving efficacy for serious human infections. Objective: The aim of this study was to ascertain the rate of prescription of a number of 'reserved'...
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...
Sykes BW, Underwood C, Greer R, McGowan CM, Mills PC.Conflicting data are presented in the current literature regarding the efficacy of omeprazole for suppressing gastric acidity in the horse. Objective: The objective of this study was to investigate the duration of intraday acid suppression achieved with two doses of omeprazole under two different dietary conditions. Methods: A four-way crossover design. Methods: Six adult Thoroughbred horses instrumented with percutaneous gastrotomy tubes were used. Intragastric pH was measured for continuous 23 h periods (08.00-07.00 h) for six consecutive days (Days 0-5). Baseline data was recorded on Day 0 ...
Corado CR, McKemie DS, Knych HK.Dextromethorphan is an N-methyl-D-aspartate (NMDA) non-competitive antagonist commonly used in human medicine as an antitussive. Dextromethorphan is metabolized in humans by cytochrome P450 2D6 into dextrorphan, which is reported to be more potent than the parent compound. The goal of this study is to describe the metabolism of and determine the pharmacokinetics of dextromethorphan and its major metabolites following oral administration to horses. A total of 23 horses received a single oral dose of 2 mg/kg. Blood samples were collected at time 0 and at various times up to 96 h post drug ad...
Shibany KA, Tötemeyer S, Pratt SL, Paine SW.Despite reports of the successful isolation of primary equine hepatocytes, there are no published data regarding the successful cryopreservation of these isolated cells. In this study, a detailed description of the procedures for isolation, cryopreservation, and recovery of equine hepatocytes are presented. Furthermore, the intrinsic clearance (Cl) and production of metabolites for three drugs were compared between freshly isolated and recovered cryopreserved hepatocytes. Primary equine hepatocytes were isolated using a two-step collagenase perfusion method, with an average cell yield of 2.47Â...
Giguère S, Burton AJ, Berghaus LJ, Haspel AD.The objective of this study was to compare the pharmacokinetics of minocycline in foals vs. adult horses. Minocycline was administered to six healthy 6- to 9-week-old foals and six adult horses at a dose of 4 mg/kg intragastrically (IG) and 2 mg/kg intravenously (i.v.) in a cross-over design. Five additional oral doses were administered at 12-h intervals in foals. A microbiologic assay was used to measure minocycline concentration in plasma, urine, synovial fluid, and cerebrospinal fluid (CSF). Liquid chromatography-tandem mass spectrometry was used to measure minocycline concentrations in ...
Epstein KL, Bergren A, Nie B, Arnold RD, Brainard BM.A lower molecular weight and molar substitution formulation (130/0.4) of hydroxyethyl starch solution has been shown to have a more sustained effect on COP and similar hemodynamic effects as a higher molecular weight and molar substitution formulation (600/0.75) in healthy horses. In humans, these pharmacodynamic characteristics are coupled with more rapid clearance and decreased adverse coagulation effects and accumulation. The objective of this study was to determine and compare the pharmacokinetics of these two formulations in horses. Eight healthy horses were given a 10Â mL/kg bolus of eac...
Uney K, Altan F, Altan S, Erol H, Arican M, Elmas M.The plasma and synovial fluid pharmacokinetics and safety of cefquinome, a 2-amino-5-thiazolyl cephalosporin, were determined after multiple intravenous administrations in sixteen healthy horses. Cefquinome was administered to each horse through a slow i.v. injection over 20 min at 1, 2, 4, and 6 mg/kg (n = 4 horses per dose) every 12 h for 7 days (a total of 13 injections). Serial blood and synovial fluid samples were collected during the 12 h after the administration of the first and last doses and were analyzed by a high-performance liquid chromatography assay. The data were evaluate...
Knych HK, Stanley SD, McKemie DS, Arthur RM, Kass PH.There is limited data describing xylazine serum concentrations in the horse and no reports of concentrations beyond 24 hours. The primary goal of the study reported here was to update the pharmacokinetics of xylazine following intravenous (IV) administration in order to assess the applicability of current regulatory recommendations. Pharmacodynamic parameters were determined using PK-PD modeling. Sixteen exercised adult Thoroughbred horses received a single IV dose of 200 mg of xylazine. Blood and urine samples were collected at time 0 and at various times for up to 96 hours and analyzed...
Corado CR, McKemie DS, Knych HK.OBJECTIVE To characterize polymorphisms of the gene for cytochrome P450 isozyme 2D50 (CYP2D50) and the disposition of 2 CYP2D50 probe drugs, dextromethorphan and debrisoquine, in horses. ANIMALS 23 healthy horses (22 Thoroughbreds and 1 Standardbred). PROCEDURES Single-nucleotide polymorphisms (SNPs) in CYP2D50 were identified. Disposition of dextromethorphan (2 mg/kg) and debrisoquine (0.2 mg/kg) were determined after oral (dextromethorphan) or nasogastric (debrisoquine) administration to the horses. Metabolic ratios of plasma dextromethorphan and total dextrorphan (dextrorphan plus dextrorph...
Bachmann V, von Salis B, Fürst A.The goal of this study was to describe the development of equine drug testing in horses in Switzerland. This was achieved through evaluation of a film made by the Institute of Forensic Medicine at the University of Basel entitled 'Doping von Rennpferden' [Doping of Race Horses], toxicological detection, 1962', the analysis of doping test results of the Swiss Equestrian Federation and by interviewing individuals of various professions who were involved in equine drug testing at the time. The study compares early and modern methods of drug testing and highlights the changes in the attitude of eq...
Winther L.The distribution of antimicrobial drugs in the equine lung is important in designing optimal dosage regimens for the treatment of lower airway infections. Several studies in horses and other species have shown that the pharmacokinetics of a drug in the lung cannot necessarily be predicted by its behaviour in plasma, and influencing factors include the class of drug, the animal species and the chosen sampling technique. This review provides a description of the target site for bacterial lower airway infections and describes the penetration of antibiotics into lung matrices. It also offers an ov...
Maxwell LK, Thomasy SM, Slovis N, Kollias-Baker C.Although fentanyl has been reported to cause CNS excitation in horses, a transdermal therapeutic system (TTS) containing this mu agonist has recently been used empirically in equine medicine to treat moderate to severe pain. A better understanding of the disposition of fentanyl following transdermal administration would facilitate the clinical use of TTS fentanyl to obtain analgesia in horses. Objective: To determine the pharmacokinetics of fentanyl following i.v. and TTS patch administration in healthy, mature horses and to evaluate the tolerance of horses to TTS fentanyl administration. Meth...
Gozalo-Marcilla M, Luna SPL, Moreira da Silva R, Crosignani N, Lopes NP, Taylor PM, Pelligand L.Pharmacokinetic (PK)/pharmacodynamic (PD) modelling offers new insights to design protocols for sedation and analgesia in standing horses. Objective: To evaluate the parameters and interactions between detomidine and methadone when given alone or combined in standing horses. Methods: Randomised, placebo-controlled, blinded, crossover. Methods: Eight adult healthy horses were given six treatments intravenously: saline (SAL); detomidine (5 μg/kg bwt; DET); methadone (0.2 mg/kg bwt; MET) alone or combined with detomidine (2.5 [MLD], 5 [MMD] or 10 [MHD] μg/kg bwt). Venous blood samples were ob...
Mealey KL, Matthews NS, Peck KE, Ray AC, Taylor TS.To compare plasma disposition of phenylbutazone and its metabolite oxyphenbutazone after i.v. administration of phenylbutazone in horses and donkeys. Methods: 4 clinically normal horses and 6 clinically normal donkeys. Methods: Blood samples were collected from each animal at time 0 (before) and 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300, 360, and 480 minutes after i.v. administration of a bolus dose of phenylbutazone. Serum was analyzed in triplicate by use of high-performance liquid chromatography for determination of phenylbutazone and oxyphenbutazone concentrations. The serum concentrat...
Arroyo MG, Couëtil LL, Nogradi N, Kamarudin MM, Ivester KM.The (R)-enantiomer of racemic albuterol (levalbuterol) has bronchodilatory properties whereas the (S)-enantiomer causes adverse effects in human airways, animal models, and isolated equine bronchi. Levalbuterol is commercially available and improves pulmonary function of asthmatic patients with a longer duration of effect than albuterol. Objective: To determine the dose at which inhaled levalbuterol produces maximal bronchodilatory effect (EDmax) and determine its duration of action in recurrent airway obstruction (RAO)-affected horses in comparison to racemic albuterol. Methods: Nine horses w...
Lillich JD, Bertone AL, Schmall LM, Ruggles AJ, Sams RA.OBJECTIVE--To document plasma, urine, and synovial fluid disposition of 2 common intra-articularly administered steroid preparations, methylprednisolone acetate (MPA) and isoflupredone acetate (IPA). DESIGN--Descriptive investigation. SAMPLE POPULATION--100 mg of MPA or 4 mg of IPA was administered to 2 groups of 4 healthy sound radiographically normal female horses. PROCEDURE--Blood samples were collected at time 0 (before) and 2, 4, 6, 8, 10, 12, 24, 36, 48, 72, and 96 hours after administration of the designated steroid. Complete urine collection for measurement of designated steroid was ac...
Moens Y, Lanz F, Doherr MG, Schatzmann U.To study the analgesic potency of the alpha2-agonist romifidine in the horse using both an electrical current and a mechanical pressure model for nociceptive threshold testing. In addition, a comparison was made with doses of detomidine and xylazine that produce equivalent degrees of sedation. Methods: Randomized, placebo-controlled, blinded cross-over study. Methods: Six adult Swiss warmblood horses, one mare and five geldings, weighing from 530 to 650 kg and aged 6-15 years. Methods: Nociceptive thresholds were measured using an electrical stimulus applied to the coronary band and using a pn...
Soraci A, Benoit E, Jaussaud P, Lees P, Delatour P.Carprofen (CPF) enantiomers and their glucuronide conjugates (GLUC) were measured in plasma and bile of horses after IV administration of the racemic compound (0.7 mg/kg of body weight). The CPF was detectable in plasma for up to 72 hours after dosing, whereas GLUC appeared early (time for maximal plasma concentration, 1 hour) and was measurable transiently at low concentration (maximal plasma concentration, 0.5 microgram/ml). The enantiospecific plasma profiles indicated a clear predominance of R-CPF, whereas the stereoselectivity of the glucuronides favored S-GLUC. At 1, 2, and 12 hours afte...
DiMaio Knych HK, Arthur RM, Taylor A, Moeller BC, Stanley SD.Dantrolene is a skeletal muscle relaxant used commonly in performance horses to prevent exertional rhabdomyolysis. The goal of the study reported here was to begin to characterize cytochrome P450-mediated metabolism of dantrolene in the horse and describe the pharmacokinetics of the compound, formulated as a capsule or a compounded paste formulation, following oral administration. Dantrolene is rapidly metabolized to 5-hydroxydantrolene both in vivo and in vitro. Preliminary work with equine liver microsomes suggest that two enzymes are responsible for the metabolism of dantrolene, as evidence...
Santschi EM, Papich MG.The disposition of drugs may differ between pregnant and nonpregnant animals, necessitating a change in dosage. We hypothesized that volume of distribution or clearance may be different for aminoglycoside antibiotics in pregnant mares vs. nonpregnant lactating mares. To examine this hypothesis, we administered gentamicin sulfate to seven Thoroughbred and Quarterhorse mares on two occasions, followed by plasma drug gentamicin assay and pharmacokinetic analysis. The first dose was administered 1-4 weeks before parturition (mean weight 578 kg) and the second dose was administered in the period 1-...
Guan F, Robinson MA.The ability to analyze biological samples for multitudinous exogenous peptides with a single analytical method is desired for doping control in horse racing. The key to achieving this goal is the capability of extracting all target peptides from the sample matrix. In the present study, theory of mixed-mode solid-phase extraction (SPE) of peptides from plasma is described, and a generic mixed-mode SPE procedure has been developed for recovering multitudinous exogenous peptides with remarkable sequence diversity, from equine plasma and urine in a single procedure. Both the theory and the develop...
Calzetta L, Rogliani P, Mattei M, Alfonsi P, Cito G, Pistocchini E, Cazzola M, Matera MG.Equine airways represent a suitable ex vivo model to study the functional impact of pharmacological treatments on human chronic obstructive pulmonary disorders, such as asthma and chronic obstructive pulmonary disease (COPD). We aimed to characterize the pharmacological interaction between the long-acting muscarinic antagonist (LAMA) tiotropium and the long-acting β-agonist (LABA) olodaterol in equine airways. The effect of tiotropium and olodaterol, administered alone and in combination at the ratio of concentrations reproducing ex vivo the concentration-ratio delivered by the currently avai...
Robertson JT, Muir WW.A xylazine and butorphanol drug combination produced minimal and transient hemodynamic effects and no significant respiratory depression when administered to 6 healthy horses. Combining xylazine and butorphanol produced a synergistic analgesic effect and provided good chemical restraint for a standing surgical procedure.
Muir WW, Reed SM, McGuirk SM.Intravenous administration of quinidine gluconate converted atrial fibrillation (AF) to sinus rhythm in 9 of 12 horses. Twelve horses that were diagnosed by ECG to have AF were administered up to 11 mg of quinidine gluconate/kg of body weight in 1.0- to 1.5-mg/kg bolus injections every 10 to 15 minutes. The total dose of quinidine administered IV ranged from 1.8 to 5.8 g. Increased ventricular rate, apprehension, and mild depression were observed during treatment. Other signs of toxicosis were not observed. One horse was successfully treated with IV administered quinidine gluconate on 3 occasi...
Kaabia Z, Dervilly-Pinel G, Popot MA, Bailly-Chouriberry L, Plou P, Bonnaire Y, Le Bizec B.Nandrolone (17β-hydroxy-4-estren-3-one) is amongst the most misused endogenous steroid hormones in entire male horses. The detection of such a substance is challenging with regard to its endogenous presence. The current international threshold level for nandrolone misuse is based on the urinary concentration ratio of 5α-estrane-3β,17α-diol (EAD) to 5(10)-estrene-3β,17α-diol (EED). This ratio, however, can be influenced by a number of factors due to existing intra- and inter-variability standing, respectively, for the variation occurring in endogenous steroids concentration levels in a si...
Wescott RB.Equine anthelmintics and the resistance of nematode parasites to anthelmintics are reviewed. Recommendations are made for effective treatment of these parasites and for procedures that can be performed to minimize the problem in the future.
Skelding AM, Valverde A.Sympathomimetic drugs mimic the physiological action of the sympathetic nervous system through interaction with adrenergic receptors. These drugs are commonly used to provide cardiovascular support in many veterinary species. Despite their common use, the literature evaluating their effectiveness can be somewhat limited depending on the species. This review details the mechanism of action of various sympathomimetic drugs and summarizes the literature that is available describing the efficacy of these drugs and their use in anesthetized veterinary species.
Maylin G, Fenger C, Machin J, Kudrimoti S, Eisenberg R, Green J, Tobin T.Aminorex, (RS)-5- Phenyl-4,5-dihydro-1,3-oxazol-2-amine, is an amphetamine-like anorectic and in the United States a Drug Enforcement Administration [DEA] Schedule 1 controlled substance. Aminorex in horse urine is usually present as a metabolite of Levamisole, an equine anthelmintic and immune stimulant. Recently, Aminorex identifications have been reported in horse urine with no history or evidence of Levamisole administration. Analysis of the urine samples suggested a botanical source, directing attention to the Brassicaceae plant family, with their contained GlucoBarbarin and Barbarin as p...
Rütten S, Schrödl W, Abraham G.Glucocorticoids are important drugs in the treatment of many inflammatory, autoimmune and allergic diseases in humans and animals. We investigated the effects of hydrocortisone and dexamethasone on TNF-α, IL-1Ra and INF-γ release in stimulated whole blood cell culture from healthy horses. Whole blood cell cultures proved to be useful for the characterization of the anti-inflammatory properties of new drugs. Diluted equine whole blood was exposed to lipopolysaccharide (LPS) and PCPwL (a cocktail consisting of phythemagglutinin E, concanavalin A, pokeweed mitogen and lipopolysaccharide) in the...
Ilomuanya M, Uboh C, Ciallella J, Li X, Liu Y, Ifudu N, Azubuike C, Igwilo C.Treatment of racehorses with bicarbonate solutions to manage acidosis and muscle cramps prior to competition is banned in Pennsylvania (PA). Use of excess bicarbonate in horses causes diarrhea, requiring treatment with an antibiotic such as metronidazole (MTNZ). At present no method exists for detecting MTNZ in equine plasma. Thus, a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the detection, quantification and confirmation of MTNZ was developed. Methods: The analyte was recovered from plasma by liquid-liquid extraction using methyl tert-butyl ether and separated on an ...
Kälin I, Henze IS, Ringer SK, Torgerson PR, Bettschart-Wolfensberger R.Medetomidine partial intravenous anaesthesia (PIVA) has not been compared to xylazine PIVA regarding quality of recovery. This clinical retrospective study compared recoveries following isoflurane anaesthesia balanced with medetomidine or xylazine. The following standard protocol was used: sedation with 7 µg·kg medetomidine or 1.1 mg·kg xylazine, anaesthesia induction with ketamine/diazepam, maintenance with isoflurane and 3.5 µg·kg·h medetomidine or 0.7 mg·kg·h xylazine, and sedation after anaesthesia with 2 µg·kg medetomidine or 0.3 mg·kg xylazine. Recovery was timed and, using vi...
Wehrman RF, Gemensky-Metzler AJ, Zibura AE, Nyhart AB, Chandler HL.OBJECTIVE To determine the safety of topical administration of 1% atropine ophthalmic solution in healthy horses by objectively measuring gastrointestinal transit time. DESIGN Randomized, masked, controlled crossover study. ANIMALS 6 adult geldings. PROCEDURES Horses were randomly assigned (3/group) to first receive topical treatment of the left eye with 1% atropine or artificial tears solution; the right eye was left untreated. After 24 hours of treatment every 6 hours, 200 nontoxic beads were administered to each horse via nasogastric intubation and treatment frequency was decreased to every...
Thomasy SM, Mama KR, Whitley K, Steffey EP, Stanley SD.In order to evaluate its potential as an adjunct to inhalant anaesthesia in horses, the pharmacokinetics of fentanyl must first be determined. Objective: To describe the pharmacokinetics of fentanyl and its metabolite, N-[1-(2-phenethyl-4-piperidinyl)maloanilinic acid (PMA), after i.v. administration of a single dose to horses that were awake in Treatment 1 and anaesthetised with isoflurane in Treatment 2. Methods: A balanced crossover design was used (n = 4/group). During Treatment 1, horses received a single dose of fentanyl (4 microg/kg bwt, i.v.) and during Treatment 2, they were anaesthet...
Jinks MR, Fontenot RL, Wills RW, Betbeze CM.To compare the efficacy and duration of effect of three local anesthetics on corneal sensitivity when administered subconjunctivally in horses. Methods: Eight healthy adult horses. Methods: A randomized, masked, crossover study design was used, with a two-week washout period between trials. The subconjunctival space of the randomly selected eye was injected with 0.2 mLs of bupivacaine (0.5%), lidocaine (2%), mepivacaine (2%), or saline. All horses received each medication once. The contralateral eye served as a control. The corneal touch threshold (CTT) was measured in both eyes with a Cochet-...
Spiess BM, Nyikos S, Stummer E, Sahin A, Naegeli H.To determine concentrations of dexamethasone in serum and urine of horses treated repeatedly with a topically administered ophthalmic dexamethasone preparation. Methods: 4 clinically normal horses (2 mares, 2 geldings). Methods: 0.1% dexamethasone ophthalmic ointment was administered to the left eye of each horse every 5 to 9 hours for 8 consecutive days, yielding an estimated cumulative dexamethasone dose of 6.4 microg/kg of body weight. Serum and urine samples were obtained before the first dexamethasone treatment, on days 4 and 8 of treatment, and 24, 48, and 96 hours after cessation of tre...
Tudor RA, Papich MG, Redding WR.To evaluate pharmacokinetics of once daily i.v. administration of gentamicin sulfate to adult horses that had abdominal surgery. Methods: Prospective study. Methods: 28 adult horses that underwent abdominal surgery for colic. Methods: 14 horses were treated with each dosage of gentamicin (i.e., 6.6 or 4 mg/kg, i.v., q 24 h) and blood samples were collected for pharmacokinetic analysis. Plasma gentamicin concentrations were measured by use of a fluorescence polarization immunoassay. Pharmacokinetic analysis measured the elimination half-life, volume of distribution, and gentamicin total systemi...
Davis JL, Kirk LM, Davidson GS, Papich MG.To determine the effects of temperature and light over a 35-day period on stability of pergolide mesylate after compounding in an aqueous vehicle. Methods: Evaluation study. Methods: Pergolide was compounded into a formulation with a final target concentration of 1 mg/mL. Aliquots of the formulation were then stored at -20 degrees, 8 degrees, 25 degrees, or 37 degrees C without exposure to light or at 25 degrees C with exposure to light for 35 days. Samples were assayed in triplicate by means of high-pressure liquid chromatography immediately after compounding and after 1, 7, 14, 21, and 35 da...
Clark C, Dowling PM, Ross S, Woodbury M, Boison JO.The macrolide antibiotic tilmicosin has potential for treating bacterial respiratory tract infections in horses. A pharmacokinetic study evaluated the disposition of tilmicosin in the horse after oral (4 mg/kg) or subcutaneous (s.c.) (10 mg/kg) administration. Tilmicosin was not detected in equine plasma or tissues after oral administration at this dose. With s.c. injection, tilmicosin concentrations reached a maximum concentration of approximately 200 ng/mL in the plasma of the horses. Tilmicosin concentrations in plasma persisted with a mean residence time (MRT) of 19 h. Maximum tissue resid...
Freeman SL, Bowen IM, Bettschart-Wolfensberger R, Alibhai HI, England GC.The cardiovascular effects of romifidine, an alpha-2 adrenoreceptor agonist, were investigated in six horses using two doses (80 and 120 microg kg(-1)) in a cross-over study design. Cardiac index and mixed venous oxygenation were significantly decreased at 15 and 30 minutes after both doses of romifidine. Systemic vascular resistance was significantly increased with romifidine (120 microg kg(-1)). Arterial blood pressure increased initially and then gradually decreased; the doses of decrease was significant at 90 and 120 minutes with romifidine 80 and 120 microg kg(-1). There were minimal diff...
