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.
Smetzer DL, Senta T, Hensel JD.Each of nine horses was treated with amphetamine alone, with atropine alone, and with amphetamine and atropine in combination. Cardiac effects of these drugs were studied by electrocardiography during resting and exercising states and immediately after exercise. Although each treatment increased heart rate significantly during the resting state, only the amphetamine plus atropine treatment increased heart rate significantly during exercise. Decrease in heart rate immediately after exercise differed significantly for each treatment; the most rapid decrease in heart rate was found after the amph...
Pocurull DW, Gaines SA, Mercer HD.Salmonella cultures were obtained from outbreaks of animal disease from 37 states and 1 territory. They were screened for resistance to 11 antimicrobial drugs. Of the 1,251 strains studied, 935 were resistant to one or more of these agents. The three most common resistance patterns were ampicillin, dihydrostreptomycin, sulfamethoxypyridazine, tetracycline; ampicillin, dihydrostreptomycin, sulfamethoxypyridazine; dihydrostreptomycin, sulfamethoxypyridazine, tetracycline. Resistance transfer was demonstrated on 267 multiply resistant cultures, of which 181 were able to transfer all or part of th...
Dybing O, Peoples SA.The determination of amphetamine in body fluids is of interest in veterinary toxicology because of the possible use of amphetamine in the doping of race horses. Many types of methods for its detection and determination have been developed. In the newest methods gas chromatography and mass spectrometry have been applied, making it possible to detect and identify 1 µg amphetamine in blood samples ( 1970).
Pyörälä S, Taponen J, Katila T.Use of antimicrobials for veterinary indications related to reproduction in cattle and horses is reviewed. Antimicrobial compounds are widely used to treat and prevent infections of reproductive organs. Total amounts of antimicrobials for such purposes, estimated by weight, are low compared with major uses in food animals. The most common reproduction-related indication in cattle is mastitis. The number of intramammary products available for treatment of mastitis in the European Union is high. Metritis and endometritis also require antimicrobial treatment of cattle and specific products for in...
Chang Y, Maylin GM, Matsumoto G, Neades SM, Catlin DH.Methods have been developed to screen for and confirm darbepoetin alfa, recombinant human EPO, and methoxy polyethylene glycol-epoetin β (PEG-epoetin β) in horse plasma. All three methods screen samples with an enzyme-linked immunosorbent assay (ELISA) and confirm by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This report focuses on PEG-epoetin β. The ELISA assay was able to detect PEG-epoetin β at 0.02 ng/mL in 50 µL of horse plasma. Many samples had high background levels of immunoreactivity; however, introducing polyethylene glycol 6000 (PEG 6000) into the samples before...
Rendle DI, Hughes KJ, Doran GS, Edwards SH.To determine the pharmacokinetics of pergolide after IV administration to horses. Methods: 8 healthy adult horses. Methods: Pergolide mesylate was administered IV at a dose of 20 μg/kg (equivalent to 15.2 μg of pergolide/kg) to each horse, and blood samples were collected over 48 hours. Pergolide concentrations in plasma were determined by means of high-performance liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were determined on the basis of noncompartmental methods. Results: After IV administration of pergolide, mean ± SD clearance, elimination half-life, a...
Laverty G, McCloskey AP, Gorman SP, Gilmore BF.The threat of antimicrobial resistance has placed increasing emphasis on the development of innovative approaches to eradicate multidrug-resistant pathogens. Biofilm-forming microorganisms, for example, Staphylococcus epidermidis and Staphylococcus aureus, are responsible for increased incidence of biomaterial infection, extended hospital stays and patient morbidity and mortality. This paper highlights the potential of ultrashort tetra-peptide conjugated to hydrophobic cinnamic acid derivatives. These peptidomimetic molecules demonstrate selective and highly potent activity against resistant b...
Sanford J.The usefulness of an antibiotic depends not only upon its antibacterial potency and spectrum but also on the prevalence of resistant organisms and the extent and severity of the adverse reactions to which it may give rise. Variations in formulation of the same compound are reflected in differences in bioavailability. These may be intentional, as in the development of long-acting preparations, but may also be unexpected following differences in drug purity, content and gastro-intestinal absorption. Individual and species differences in treated animals also result in variations in bioavailabilit...
Foreman JH, Ruemmler R.Using an adjustable heart bar shoe model of foot pain, the objective of this study was to test the hypothesis that the combined use of phenylbutazone (PBZ) and flunixin meglumine (FM) would prove more efficacious in alleviating lameness than either drug alone. Methods: One hour after induction of lameness at weekly intervals, 8 healthy adult Thoroughbred horses randomly underwent one of 4 i.v. treatments: saline (SAL) placebo (1 ml/45 kg bwt), PBZ (4.4 mg/kg bwt), FM (1.1 mg/kg bwt) or PBZ+FM (at the same dosages as given individually). Heart rate (HR) and lameness score (LS) responses were as...
Jonckheere JA, Thienpont LM, De Leenheer AP, De Backer P, Debackere M, Belpaire FM.A method has been developed for quantification of bromhexine in plasma using gas chromatography mass spectrometry with selected ion monitoring. A deuterium labelled analogue was synthesized and used as the internal standard. To evaluate the gas chromatographic electron capture detection method described earlier, 23 plasma samples have been analysed by both techniques. Although a good correlation was shown, selected ion monitoring was superior to the electron capture detection method for levels below 3 ng ml-1. The mass spectrometric method has also been used to set up a pharmacokinetic study o...
Fradette ME, Céleste C, Richard H, Beauchamp G, Laverty S.To evaluate the effects of continuous oral administration of phenylbutazone on serum and synovial fluid biomarkers of skeletal matrix metabolism in horses. Methods: 11 adult female horses without clinical or radiographic evidence of joint disease. Methods: Horses were randomly assigned to control or treatment groups. Phenylbutazone was administered orally twice daily at a dose of 4.4 mg/kg for 3 days to the treatment group and subsequently at a dose of 2.2 mg/kg for 7 days. Serum and radiocarpal synovial fluid samples were obtained at baseline and thereafter at regular intervals for 4 weeks. B...
Whittem T, Firth EC, Hodge H, Turner K.This study examined the pharmacokinetics of steady-state phenylbutazone and single bolus intravenous gentamicin when administered together in the horse. The trial design was completed as a cross-over with seven thoroughbred horses. In the first phase each horse received 2.2 mg/kg gentamicin intravenously. After a 2-week washout, each horse received 4.4 mg/kg phenylbutazone intravenously every 24 h for 5 days. On the fourth day each horse received gentamicin as before. Plasma was harvested for gentamicin concentration determination by fluorescence polarization immunoassay and for phenylbutazone...
Raidal SL, Andrews FM, Nielsen SG, Trope G.Limited data are available on the relative pharmacokinetics and pharmacodynamics of different omeprazole formulations. Objective: To compare pharmacokinetic and pharmacodynamic effects of a novel omeprazole formulation against a currently registered product. Methods: Masked 2 period, 2 treatment crossover. Methods: Twelve clinically healthy horses were studied over two 6-day treatment periods. Horses were randomly assigned to receive a novel omeprazole paste (Ulcershield: ULS) or a currently registered reference omeprazole product (OMO). Gastric pH was measured continuously for 10 h on the day...
Komáromy AM, Andrew SE, Sapp HL, Brooks DE, Dawson WW.The goal of our study was the evaluation of a practical method for the recording of flash electroretinograms (ERGs) in sedated, standing horses with the DTL microfiber electrode. Methods: The horses were sedated intravenously with detomidine hydrochloride (0.015 mg/kg). The pupil was dilated and the auriculopalpebral nerve was blocked. The ERGs were recorded with the active electrode on the cornea (DTL), the reference electrode near the lateral canthus, and the ground electrode over the occipital bone. The light intensities of the white strobe light were 0.03 cd x s/m2 (scotopic) and 3 cd x s/...
Moorman VJ, Bass L, King MR.To determine the effects of 3 α2-adrenergic receptor agonists (α2-ARAs), alone or in combination with butorphanol tartrate, on objective measurements of lameness in horses. Methods: 17 adult polo horses with naturally occurring forelimb or hind limb lameness (or both). Methods: In a crossover design, each horse received each protocol (saline [0.09% NaCl] solution [2 mL, IV] or xylazine hydrochloride [0.33 mg/kg, IV], detomidine hydrochloride [0.007 mg/kg, IV], or romifidine hydrochloride [0.033 mg/kg, IV] alone or in combination with butorphanol [0.007 mg/kg, IV]) in random order, with a was...
Knych HK, Mama K, Oakleaf M, Harrison LM, McKemie DS, Kass PH.The goal of this study was to determine plasma, urine, and synovial fluid concentrations and describe the effects on biomarkers of cartilage toxicity following intra-articular dexmedetomidine administration to horses. Methods: 12 research horses. Methods: Horses received a single intra-articular administration of 1 μg/kg or 5 μg/kg dexmedetomidine or saline. Plasma, urine, and synovial fluid were collected prior to and up to 48 hours postadministration, and concentrations were determined. The effects on CS846 and C2C were determined in synovial fluid at 0, 12, and 24 hours postadministration...
Morton AJ, Grosche A, Matyjaszek SA, Polyak MM, Freeman DE.The effects of prostaglandins and nonsteroidal anti-inflammatory drugs (NSAIDs) on repair of equine intestinal mucosa are important since most horses with gastrointestinal diseases are routinely treated with NSAIDs, such as flunixin meglumine (FM), and these drugs can be toxic to equine gastrointestinal mucosa. Objective: Flunixin meglumine would not affect recovery of equine colonic mucosa in vitro, 18 h after a reversible ischaemic injury. Methods: In 14 anaesthetised horses, a segment of pelvic flexure was subjected to 2 h of ischaemia and the horses were allowed to recover for 18 h. Seven ...
Tanaka T, Aramaki S, Momose A.A thin-layer chromatographic screening procedure for some basic, neutral and acidic drugs was developed using 3 ml of horse plasma. Chloroform-2-propanol (95:5, v/v) was used as the extraction solvent. The drugs were identified by a high-performance thin-layer chromatographic plate and spraying successively with some detection reagents. In this study, the extraction recovery rates and the detection limits were determined at the same time.
Handing KB, Shabalin IG, Szlachta K, Majorek KA, Minor W.Serum albumin (SA) is the main transporter of drugs in mammalian blood plasma. Here, we report the first crystal structure of equine serum albumin (ESA) in complex with antihistamine drug cetirizine at a resolution of 2.1Å. Cetirizine is bound in two sites--a novel drug binding site (CBS1) and the fatty acid binding site 6 (CBS2). Both sites differ from those that have been proposed in multiple reports based on equilibrium dialysis and fluorescence studies for mammalian albumins as cetirizine binding sites. We show that the residues forming the binding pockets in ESA are highly conserved in h...
Martin F, Eydal M, Höglund J, Tydén E.The equine roundworm Parascaris univalens has developed resistance to the three anthelmintic substances most commonly used in horses. The mechanisms responsible for resistance are believed to be multi-genic, and transport proteins such as the P-glycoprotein (Pgp) family have been suggested to be involved in resistance in several parasites including P. univlaens. To facilitate further research into the mechanisms behind drug metabolism and resistance development in P. univalens we aimed to develop an in vitro model based on larvae. We developed a fast and easy protocol for hatching P. univalens...
Drudge JH, Lyons ET, Tolliver SC.Critical tests were carried out in 10 horses to evaluate the antiparasitic activity of febantel given alone or with trichlorfon. Paste formulations were administered intraorally at dose levels of 6 mg of febantel (active ingredient)/kg and 35 mg of trichlorfon (active ingredient)/kg. In 5 tests with febantel alone, removal of 100% was recorded for mature or immature Parascaris equorum from 2 infected horses. Strongylus vulgaris from 4 infected horses, S edentatus from 5 infected horses, and mature Oxyuris equi from 1 infected horse; and removal of 96% was recorded for small strogyles from 1 ho...
Delatour P, Benoit E, Bourdin M, Gobron M, Moysan F.After the administration of racemic ketoprofen and carprofen to man, both enantiomers of each compound exhibit similar plasma profiles. This contrasts with the rat where the active S(+) enantiomer is predominant. For carprofen, regardless of the route of administration, the R(-) enantiomer is predominant in the plasma of all investigated animal species. The S(+)/R(-) ratio of the "areas under the curves" during the time course of the kinetics, is: 0.60 in dogs, 0.53 in Yucatan micro-pigs, 0.48 in mini-goats, 0.67 in calves and 0.19 in horses. For ketoprofen, the S(+) enantiomer is predominant ...
Koenig J, Cote N.Colic is a common problem encountered in equine practice. Alteration of gastrointestinal motility is often the underlying cause for abdominal pain. Gastrointestinal motility can be measured as myoelectric activity, mechanical activity, and transit of intraluminal contents. Regulation of motility is based on a complex interaction between central innervation, autonomic innervation, and the enteric nervous system. Various humoral and neurochemical substances are required to interact flawlessly to allow propulsive motility. Ileus is defined as the absence of propulsive aboral movement of gastroint...
Lescun TB, Ward MP, Adams SB.To compare gentamicin concentrations achieved in synovial fluid and joint tissues during IV administration and continuous intra-articular (IA) infusion of the tarsocrural joint in horses. Methods: 18 horses with clinically normal tarsocrural joints. Methods: Horses were assigned to 3 groups (6 horses/group) and administered gentamicin (6.6 mg/kg, IV, q 24 h for 4 days; group 1), a continuous IA infusion of gentamicin into the tarsocrural joint (50 mg/h for 73 hours; group 2), or both treatments (group 3). Serum, synovial fluid, and joint tissue samples were collected for measurement of gentami...
Stammwitz V, Honnens Ä, Hochhuth D, Schuberth HJ.Between 2015 and 2017, a marked increase of anaphylactic-like reactions after intravenous administration of gentamicin was observed first in horses and, later, also in humans. This worldwide issue led to safety measures including product recalls and safety warnings. Here, a German Marketing Authorization Holder (MAH) of an early and intensely affected veterinary product containing gentamicin describes the clinical approach of the company to analyze the root cause and identify the causative agent in the active pharmaceutical ingredient (API). The pharmacovigilance data of the MAH are presented,...
Dyke TM, Sams RA.The objective of this study was to determine the urinary excretion of methylxanthines in horses following ingestion of chocolate over eight days. The study was performed in response to gas chromatography-mass spectrometry (GC-MS) confirmation of the presence of caffeine in a positive urine test in a racehorse. The trainer of the horse alleged that he often administered chocolate-coated peanuts as treats to his horses, and he believed that the ingestion of chocolate was responsible for the positive urine test. The urinary excretion of theobromine and caffeine after the ingestion of chocolate-co...
Choi TLS, Wong JKY, Kwok WH, Curl P, Mechie S, Wan TSM.Methylstenbolone (2,17α-dimethyl-5α-androst-1-en-17β-ol-3-one) is a synthetic anabolic and androgenic steroid (AAS) sold as an oral 'nutritional supplement' under the brand names 'Ultradrol', 'M-Sten' and 'Methyl-Sten'. Like other AASs, methylstenbolone is a prohibited substance in both human and equine sports. This paper describes the studies of the in vitro and in vivo metabolism of methylstenbolone in horses using LC/HRMS, GC/MS and GC/MS/MS. Phase I in vitro metabolic study of methylstenbolone was performed using homogenised horse liver. Hydroxylation was the only biotransformation obse...
Viljanto M, Kaabia Z, Taylor P, Hincks P, Muir T, Habershon-Butcher J, Bailly-Chouriberry L, Scarth J.Boldenone is an anabolic-androgenic steroid (AAS) that is prohibited in equine sports. However, in certain situations, it is endogenous, potentially formed by the microbes in urine. An approach to the differentiation based on the detection of the biomarkers Δ1-progesterone, 20(S)-hydroxy-Δ1-progesterone and 20(S)-hydroxyprogesterone was assessed, and their concentrations were monitored in the urine of untreated female horses (n = 291) alongside boldenone, boldienone, testosterone and androstenedione. Using an ultra-sensitive analytical method, boldenone (256 ± 236 pg/mL, n = 2...
Benoit M, Lingen K, Taddei LM, Heffron BT, Hurt L, Lokanc JA, Lingner K, Cardenas E, Flores S, Mayer D, Pilipiak D, Folker-Calderon D, Negrusz A.Pyrilamine (mepyramine) is an H1-receptor antagonist used in human and veterinary medicine. It has the potential to produce central nervous system effects in horses and therefore may have some impact on an outcome of a horse race. A single oral dose of pyrilamine (300 mg/horse) was given to three animals. Serum samples were collected before drug administration and at 0.25, 0.5, 1, 2, 4, 6, 24, 48, 72, 96, 120, and 144 h, and 7, 8, 9, 10, 11, 12, and 13 days post-administration. Urine samples were collected at 0-1, 1-2, 2-4, 4-6, 24, 48, 72, 96, 120, and 144 h, and 7, 8, 9, 10, 11, 12, 13 days ...
Authie EC, Garcia P, Popot MA, Toutain PL, Doucet M.Equine antidoping rules were established to prevent a horse's performance being altered after the administration of prohibited substances, including approved drugs used for legitimate treatment. Veterinarians have to advise owners or trainers on appropriate withholding times to guarantee that their horses may safely compete after drug administration. In order to propose tailored withdrawal times, several horse organisations released detection time (DT) values, for the main veterinary drugs used in horses. One of the possible limits to the information provided by published DTs in horses is the ...
Stack A, Schott HC.Adverse drug reactions to trimethoprim-sulphonamide combinations are common in many species, manifesting as gastrointestinal tract disorders, dermatopathies and blood dyscrasias. In this case series, neurological abnormalities in 4 horses being treated with trimethoprim-sulphonamide combinations at normal dosages and in one foal that received an overdose are described. The horses developed hypermetric gait, agitation and erratic behaviour. All signs resolved once medication was withdrawn, and no horse had residual deficits. No other cause for observed neurological deficits could be determined....
Edmonds RE, Garvican ER, Smith RK, Dudhia J.To provide evidence to support recommendations regarding the co-administration of drugs with mesenchymal stem cell (MSC) therapy. Objective: To determine the influence of sedatives, local anaesthetic and corticosteroids on MSC viability and proliferation, in comparison to somatic cells derived from tendon (TDCs). Methods: In vitro cell culture. Methods: MSCs (n = 3) and TDCs (n = 2) were cultured in media containing a clinically relevant dose range of xylazine, romifidine, detomidine and butorphanol, mepivacaine, methylprednisolone, or triamcinolone acetonide. Cell viability in suspension cult...
