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.
Lawless SP, Moorman VJ, Hendrickson DA, Mama KR.To compare efficacy and safety of a continuous rate infusion of detomidine hydrochloride and romifidine hydrochloride for standing elective bilateral laparoscopic ovariectomy in mares. Methods: Blinded, randomized prospective clinical study. Methods: Eighteen healthy mares presenting for elective bilateral ovariectomy METHODS: Mares were randomly assigned to one of two sedation protocols. Prior to surgery, baseline head height, heart rate, respiratory rate, and postural sway were recorded. An IV loading dose of α2-agonist (46 μg/kg romifidine or 13.9 μg/kg detomidine) was administered. S...
Ryan D, McKemie DS, Kass PH, Puschner B, Knych HK.The increasing availability of cannabidiol (CBD) and anecdotal reports of its anti-inflammatory effects has garnered it much interest in the equine industry. The objectives of the current study were to (1) describe the pharmacokinetics of oral CBD in exercising thoroughbreds, (2) characterize select behavioral and physiologic effects, and (3) evaluate effects on biomarkers of inflammation using an ex vivo model. This study was conducted in a randomized balanced 3-way crossover design with a two-week washout period between doses. Horses received a single oral dose (0.5, 1, and 2 mg/kg) of CBD...
Flynn H, Cenani A, Brosnan RJ, DiMaio Knych HK, de Araujo Aguiar AJ.To determine the pharmacokinetics and pharmacodynamics of high-concentration formulation of buprenorphine (1.8 mg mL; Simbadol) following subcutaneous (SC) administration in horses. Methods: Prospective, randomized, crossover trial. Methods: A group of six healthy adult horses weighing 521-602 kg. Methods: On three occasions, Simbadol (0.005 mg kg; treatment S5), (0.0025 mg kg; treatment S2.5) or saline (treatment SAL) were administered SC at least 7 days apart in random order. Electrical nociceptive threshold (ENT) measured on the neck region, physiologic variables, locomotor activity, degree...
Leventhal HR, McKenzie HC, Estell K, Council-Troche M, Davis JL.The objective of this study was to determine the pharmacokinetics and tolerability of tulathromycin (Draxxin ; 2.5 mg/kg once) after intramuscular (IM), subcutaneous (SC), and slow intravenous (IV) administration to six adult horses. A three-phase design and 4-week washout period were used. Drug concentrations in blood and bronchoalveolar lavage (BAL) samples were determined by ultra-performance liquid chromatography tandem mass spectrometry and pharmacokinetic parameters calculated using noncompartmental analysis. Following SC and IM administration, all horses exhibited sweating, discomfort,...
You Y, Proctor RM, Guo K, Li X, Xue E, Guan F, Robinson MA.High-resolution mass spectrometry (HRMS) is a very powerful technology for equine doping control analysis. The more recently developed hybrid type of Orbitrap-based HRMS instrument allows for both targeted and non-targeted screening analyses in a single liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS) run. In the present study, an LC-HRMS/MS method was developed and validated to detect prohibited substances in equine sports. The substances were recovered from equine plasma by liquid-liquid extraction (LLE) using methyl tert-butyl ether and were separated on a C18 rev...
Skrzypczak H, Reed R, Brainard B, Sakai D, Barletta M, Quandt J, Smyth C, Ruch M, Knych H.Matrix fentanyl patches have not been investigated in horses and may represent an effective means of providing analgesia over an extended time period without venous catheterisation. Objective: To describe the pharmacokinetics of a matrix transdermal fentanyl patch in horses. Methods: Randomised experiment, Latin-square design. Methods: Six adult horses were given each of three treatments with a 96-hour washout. For each treatment, two 100 µg/h matrix fentanyl patches were applied to the inguinal region (TXA), metacarpus (TXM) or ventral tail base (TXT) for 72 hours. Blood samples for fentan...
Keen B, Cawley A, Fouracre C, Pyke J, Fu S.The emergence of novel doping agents is a continuous issue for analysts who aim to maintain the integrity of horseracing together with the well-being and safety of the animals and riders involved. Untargeted mass spectrometric analysis presents a potential improvement for antidoping as it enables the detection of compounds being indirectly affected by an administered drug. In this study, liquid chromatography-high-resolution mass spectrometry was used to investigate a 12-horse administration study of the synthetic opioid, butorphanol. A mass spectrometric workflow capable of detecting metaboli...
Knych HK, Magdesian KG.Equine antimicrobial therapy has advanced over time with the availability of increasing pharmacokinetic and pharmacodynamic studies in horses, allowing for greater evidence-based clinical decision-making. However, many challenges to optimal antimicrobial therapy remain and further research is needed to address these areas. There are a limited number of approved antimicrobials for use in horses, which creates a need for compounded preparations for clinicians. Extra-label drug use is commonplace in equine practice, which warrants continual education of veterinarians about policies and updates. P...
Suthar A, Maji C, Gopalkrishnan A, Raval SH, Kumar R, Kumar S.Theileria equi and Babesia caballi are the causative agents of equine piroplasmosis (EP). Currently, imidocarb dipropionate (ID) is the only available drug for treating the clinical form of EP. Serious side effects and incomplete clearance of infection is a major drawback of ID. Heat-shock proteins (Hsp) play a vital role in the life cycle of these haemoprotozoans by preventing alteration in protein conformation. These Hsp are activated during transmission of EP sporozoites from the tick vector (poikilotherm) to the natural host (homeotherm) and facilitate parasite survival. In the present stu...
Abu-Basha EA, Bani Ismail Z, Ababneh MM, Hamzeh E, Gehring R.This study was designed to investigate the safety and pharmacokinetic (PK) profile of tildipirosin in horses after intravenous (i.v.) and subcutaneous (s.c.) injection of a single dose at 4 mg/kg of body weight (b.w.). A total of 12 healthy mixed breed horses were used in the study. Horses were monitored for systemic and local adverse effects, and whole blood samples were collected for hematology and plasma biochemistry analysis at time (0) and at 6, 24, and 72 h after drug administration. For PK analysis, blood samples were collected at pre-determined times before and after tildipirosin adm...
Gretler SR, Finno CJ, Kass PH, Knych HK.In humans, the drug metabolizing enzyme CYP2D6 is highly polymorphic resulting in substantial differences in the metabolism of drugs including anti-arrhythmics, neuroleptics, and opioids. The objective of this study was to phenotype a population of 100 horses from five different breeds and assess differences in the metabolic activity of the equine CYP2D6 homolog using codeine as a probe drug. Administration of a probe drug is a common method used for patient phenotyping in human medicine, whereby the ratio of parent drug to metabolite (metabolic ratio, MR) can be used to compare relative enzym...
Shane SE, Langston VC, Wills RW, Denney WS, Knych H, Fontenot RL, Meyer RE, Natalini CC.An ideal dexmedetomidine protocol has yet to be determined for standing sedation in horses. It was hypothesized that an IV bolus followed by CRI dexmedetomidine would have a quicker increase in plasma concentrations compared with repeated IM injections. In a crossover design, eight adult, female horses were randomly placed into two groups: the CRI group (IV bolus dexmedetomidine at 0.005 mg/kg followed by a CRI at 0.01 mg/kg/h for 15 min then 0.005 mg/kg/h for 60 min) and the IM group (dexmedetomidine at 0.01 mg/kg, followed by 0.005 mg/kg in 30-min intervals for 60 min). Clearance and...
Mikhail E, Siccardi E, Bawazir A, Rajesh A, Prathyush S, Al Wazani DMK, Sabeek M, John T.IOX-2 is a potent inhibitor of enzyme prolyl hydroxylases-2 (PHD) that plays a critical role in regulating hypoxia inducible factor (HIF) abundance and oxygen homeostasis. Federation for Equestrian Sports has listed HIF activators as prohibited substances to prevent their usage in doping. Consequently, it became essential to develop adequate knowledge and testing methods to detect it in equine sports drug testing samples. The validated method utilizes ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry in order to detect extremely low concentration of the ...
Studer N, Bernal SD, Thormann W, Levionnois O, Spadavecchia C.To evaluate the antinociceptive effect of a bolus of intravenous levomethadone administered to horses during romifidine constant rate infusion (CRI). Methods: Prospective, randomized, masked, crossover experimental study. Methods: A group of eight adult Warmblood horses (seven geldings, one mare) aged 6.6 ± 4.4 years, weighing 548 ± 52 kg [mean ± standard deviation (SD)]. Methods: Levomethadone 0.1 mg kg or an equivalent volume of saline (control) was administered intravenously to standing horses 60 minutes after starting a romifidine CRI. Blood samples to quantify romifidine and levomethad...
Broberg MN, Knych H, Bondesson U, Pettersson C, Stanley S, Thevis M, Hedeland M.Selective Androgen Receptor Modulators (SARMs) have anabolic properties but less adverse effects than anabolic androgenic steroids. They are prohibited in both equine and human sports and there have been several cases of SARMs findings reported over the last few years. The aim of this study was to investigate the metabolite profile of the SARM ACP-105 (2-chloro-4-[(3-endo)-3-hydroxy-3-methyl-8-azabicyclo[3.2.1]oct-8-yl]-3-methylbenzonitrile) in order to find analytical targets for doping control. Oral administration of ACP-105 was performed in horses, where blood and urine samples were collect...
Loganathan D, Yi R, Patel B, Zhang J, Kong N.Resolution of cathinone enantiomers in equine anti-doping analysis is becoming more important to distinguish the inadvertent ingestion of plant-based products from those of deliberate administration of designer synthetic analogs. With this in mind, a rapid and sensitive method was developed and validated for the detection, resolution and quantitative determination of cathinone enantiomers in horse blood plasma and urine. The analytes were recovered from the blood plasma and urine matrices by using a liquid-liquid extraction after adjusting the pH to 9. The recovered analytes were derivatized w...
McNeal CD, Ryan CA, Berghaus LJ, Credille BC, Lo CP, Fajt VR.Cephalosporin antimicrobials can be utilized for the treatment of sepsis in neonatal foals, particularly when an aminoglycoside is contraindicated. Some cephalosporins, however, are not utilized because of cost, sporadic availability, or uncertainty about efficacy. The plasma disposition of ceftazidime, a third-generation cephalosporin with a broad spectrum of activity against a wide variety of gram-negative bacteria and minimal renal side effects has not been reported in neonatal foals. In this study, the plasma disposition of single intravenous (IV) and intramuscular (IM) doses of ceftazidim...
Pirie RS, Mueller HW, Engel O, Albrecht B, von Salis-Soglio M.Ciclesonide is a glucocorticoid prodrug, already registered for human use. Due to its mode of action and inhaled route of administration, it was considered an appropriate treatment option for horses with severe equine asthma. Although the efficacy of inhaled ciclesonide has been demonstrated in horses with asthma exacerbations under controlled mouldy hay challenge conditions, it has not yet been reported under field conditions. Objective: To assess the effectiveness and safety of inhaled ciclesonide for the treatment of severe equine asthma. Methods: Prospective, multicentre, placebo-controlle...
Stucki M, Voegel CD, Binz TM, Kraemer T, Lavaud A, Voelter K.Equine sport agencies list steroids as prohibited substances for competing horses. Objective: The objective of this study was to investigate if the controlled substances dexamethasone and prednisolone are detectable in equine serum and urine samples during and after treatment with eye drops and if this can generate a positive doping test. Methods: Prospective cohort study. Methods: The study cohort included 11 horses. One eye of the horses was treated with either dexamethasone (Maxitrol 0.1%, n = 5 eyes) or prednisolone (Pred forte 1%, n = 6 eyes) eye drops 3 times daily for 14 days. Dexa...
Sullivan SN, Cole SL, Stewart MC, Brokken MT, Durgam S.To investigate the effects of triamcinolone acetonide (TA) and methylprednisolone acetate (MPA) on the viability of resident cells within the fibrocartilage on the dorsal surface of the deep digital flexor tendon (FC-DDFT) and fibrocartilage on the flexor surface of the navicular bone (FC-NB) of horses. Methods: 12 to 14 explants of FC-DDFT and of FC-NB from grossly normal forelimbs of 5 cadavers of horses aged 9 to 15 years without evidence of musculoskeletal disease. Methods: Explants were incubated with culture medium (control) or TA-supplemented (0.6 or 6 mg/mL) or MPA-supplemented (0.5 or...
Kilcoyne I, Nieto JE, Galuppo LD, Dechant JE.To determine the median time to maximum concentration (t) of amikacin in the synovial fluid of the tarsocrural joint following IV regional limb perfusion (IVRLP) of the drug in a saphenous vein of horses. Methods: 7 healthy adult horses. Methods: With each horse sedated and restrained in a standing position, a 10-cm-wide Esmarch tourniquet was applied to a randomly selected hind limb 10 cm proximal to the point of the tarsus. Amikacin sulfate (2 g diluted with saline [0.9% NaCl] solution to a volume of 60 mL) was instilled in the saphenous vein over 3 minutes with a peristaltic pump. Tarsocrur...
Kuroda T, Minamijima Y, Niwa H, Tamura N, Mita H, Fukuda K, Kaimachi M, Suzuki Y, Enoki Y, Taguchi K, Matsumoto K, Toutain PL, Bousquet-Melou A....First-generation cephalosporins have good activity against gram-positive bacteria and are extensively used in horses. There are few reports of pharmacokinetics and pharmacodynamics (PK/PD) analysis of cephalosporins in horses. Objective: To optimise the dosages of the two first-generation cephalosporins cephalothin (CET) and cefazolin (CEZ) in horses using PK/PD concepts. Methods: Experimental study with single administration. Methods: Drug plasma concentrations following a single intravenous (i.v.) administration of 22 mg/kg bodyweight (bwt) CET in 12 horses and of 10 mg/kg bwt CEZ in six h...
Riggs CM, Thompson SL, So YM, Wong JKY, Wan TSM, Robinson P, Stewart BD, Ho ENM.Administration of bisphosphonates, including tiludronic acid, to Thoroughbred racehorses below 3 and a half years of age is prohibited in most racing jurisdictions. Objective: To determine if evidence of administration of tiludronic acid could be obtained from analysis of blood and urine samples beyond 40 days after administration. Methods: Retrospective cohort. Methods: Horses maintained in a highly controlled environment and treated with Tildren®a were selected from clinical records. Twenty-four horses were identified, 21 of which were still in race training. Blood and urine samples were c...
Wise JC, Hughes KJ, Edwards S, Jacobson GA, Narkowicz CK, Raidal SL.Omeprazole preparations vary in bioavailability in horses. Objective: To characterize the pharmacokinetics and pharmacodynamics of an existing enteric-coated oral omeprazole paste (REF) and a novel, in-feed, enteric-coated dry granule preparation (NOV). Methods: Twelve Standardbred/Thoroughbred mares free from clinical disease. Methods: A prospective, blinded randomized interventional study was trial, conducted in 3 parts: (a) bioavailability study, (b) dose titration study, and (c) comparative clinical pharmacodynamic study, each using a blocked crossover design. Results: Consistent with the ...
Current drug metabolismDecember 19, 2020
Volume 22, Issue 3 215-223 doi: 10.2174/1389200221666201217141025
Hu SX, Ernst K, Benner CP, Feenstra KL.Pharmacokinetic and pharmacodynamic assessment of ester-containing drugs can be impacted by hydrolysis of the drugs in plasma samples post blood collection. The impact is different in the plasma of different species. Objective: This study evaluated the stability of a prodrug, ketoprofen methylester (KME), in commercially purchased and freshly collected plasma of mouse, rat, dog, cat, pig, sheep, cattle and horse. Methods: KME hydrolysis was determined following its incubation in commercially purchased and freshly collected plasma of those species. Different esterase inhibitors were evaluated f...
Robinson MA, Stefanovski D, You Y, Boston RC, Soma LR.Capsaicinoids deter horses from chewing on bandages and are applied topically to provide analgesia to musculoskeletal injuries. They are banned during competition due to their nerve blocking properties. The pharmacokinetics of oral (PO) and direct gastric administration via nasogastric tube (NG), or topical (TOP) administration of two capsaicinoid-containing products were investigated, and the withdrawal times required prior to competition were estimated. Capsaicin (CAP) and dihydrocapsaicin (DCAP) were quantified in plasma, and both compounds were best described by a delayed absorption two co...
Klingberg J, Cawley A, Shimmon R, Fu S.The constant evolution of the illicit drug market makes the identification of unknown compounds problematic. Obtaining certified reference materials for a broad array of new analogues can be difficult and cost prohibitive. Machine learning provides a promising avenue to putatively identify a compound before confirmation against a standard. In this study, machine learning approaches were used to develop class prediction and retention time prediction models. The developed class prediction model used a naïve Bayes architecture to classify opioids as belonging to either the fentanyl analogues, AH...
Bousquet-Mélou A, Schneider M, El Garch F, Broussou DC, Ferran AA, Lallemand EA, Triboulloy C, Damborg P, Toutain PL.Marbofloxacin (MBX), a fluoroquinolone (FQ), is considered as a critical antibiotic requiring antimicrobial susceptibility testing (AST) for prudent use. No clinical breakpoint (CBP) currently exists to interpret the results of such tests in horses. Objective: To compute PK/PD cut-offs (PK/PDCO ) that is one of the three minimum inhibitory concentrations (MICs) considered establishing a CBP for antimicrobial susceptibility test interpretation. Methods: A meta-analysis conducted by combining five sets of previously published pharmacokinetic data, obtained in clinical and nonclinical settings. M...
Schoster A, Amsler M, Kirchgaessner C, Saleh L, Schwarzwald C, Schmitt S.The optimal dosage regimen of gentamicin in horses is still under investigation. The objectives of this study were to determine gentamicin plasma concentrations in hospitalized horses treated with 10 mg/kg gentamicin (IV, q 24 h) and to determine whether a plasma concentration to minimum inhibitory concentration (MIC) ratio of 10:1 is reached for equine pathogens using this dose. Methods: Prospective clinical observational study; retrospective study on MICs of 131 gram-negative bacteria isolated from horses (2012-2015). Methods: University teaching hospital. Methods: Ninety-eight horses >...
Silva MG, Bastos RG, Stone Doggett J, Riscoe MK, Pou S, Winter R, Dodean RA, Nilsen A, Suarez CE.The most common apicomplexan parasites causing bovine babesiosis are Babesia bovis and B. bigemina, while B. caballi and Theileria equi are responsible for equine piroplasmosis. Treatment and control of these diseases are usually achieved using potentially toxic chemotherapeutics, such as imidocarb diproprionate, but drug-resistant parasites are emerging, and alternative effective and safer drugs are needed. The endochin-like quinolones (ELQ)-300 and ELQ-316 have been proven to be safe and efficacious against related apicomplexans, such as Plasmodium spp., with ELQ-316 also being effective aga...
Lees P, Sedgwick AD, Higgins AJ, Pugh KE, Busch U.The novel non-steroidal anti-inflammatory drug (NSAID) miloxicam was administered intravenously to six New Forest ponies at a dosage rate of 0.6 mg/kg in a two-part cross-over study. In each part, three horses received miloxicam and three were given a placebo preparation. The actions of miloxicam, compared to placebo, were assessed in a carrageenan-sponge model of acute inflammation. The rise in skin temperature over the site of the acute inflammatory reaction was less in treated ponies, but differences were not statistically significant. Concentrations of the enzymes acid phosphatase (AP) and...
Kwan C, Bell R, Koenig T, Bischofberger A, Horadagoda N, Perkins NR, Jeffcott LB, Dart AJ.Evaluate synovial fluid cytology, total protein concentration and viscosity after intra-articular administration of combined pentosan polysulfate and glucosamine in horses. Methods: Ten adult Standardbred horses had each carpal joint (n = 20) randomly assigned to one of two treatments: control (5 mL saline) or treated (pentosan polysulfate and glucosamine). All horses received an intra-articular injection every 7 days for 3 weeks and synovial fluid samples were collected on days 1 (baseline), 2, 3, 7, 8, 9, 14, 15, 16 and 21. Synovial fluid variables measured included total protein concentrati...
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 ...
Wojtasiak-Wypart M, Soma LR, Rudy JA, Uboh CE, Boston RC, Driessen B.Romifidine HCl (romifidine) is an α(2)-agonist commonly used in horses. This study was undertaken to investigate the pharmacokinetics (PK) of romifidine following intravenous (i.v.) administration and describe the relationship between PK parameters and simultaneously recorded pharmacodynamic (PD) parameters. Romifidine (80 μg/kg) was administered by i.v. infusion over 2 min to six adult Thoroughbred horses, and plasma samples were collected and analyzed using liquid chromatography-mass spectrometry. Limit of quantification was <0.1 ng/mL. PD parameters and arterial blood gases were measur...
Lowden S, Gray S, Dawson K.The horse biting louse (Werneckiella equi) is a common global equine ectoparasite. To our knowledge, benzoyl(phenyl)urea insecticides (triflumuron, diflubenzuron) commonly used as sheep lousicides, have not been evaluated for efficacy against W. equi. The aim of this study was to determine louse control efficacy, general wellness and dermal safety following triflumuron application as a backline pour-on to horses. Two efficacy trials using 25 adult naturally infested lousy horses, and a dermal safety trial using 10 adult louse-free horses were conducted over a 14-month period. Lousy animals wer...
Ryan CA, Sanchez LC, Giguère S, Vickroy T.Proton pump inhibitors (PPIs) are a mainstay of treatment for acid-related ulceration in man and horses. Currently, only an oral preparation of omeprazole is approved for use in horses in the USA. Intravenous administration of a PPI would provide a useful therapeutic alternative for those foals in which oral medication is not feasible. Objective: To investigate the pharmacokinetics and pharmacodynamics of pantoprazole following i.v. or intragastric administration in healthy neonatal foals. Methods: Seven healthy foals age 6-12 days at the start of the study were evaluated. Treatments included ...
de Vries A, Pakkanen SA, Raekallio MR, Ekiri A, Scheinin M, Taylor PM, Vainio OM.To investigate the effects of MK-467 on sedation quality, and cardiopulmonary and pharmacokinetic variables in horses sedated intravenously (IV) with romifidine. Methods: Experimental, randomized, crossover design. Methods: Seven healthy mares. Methods: Romifidine (80 μg kg-1 ; R) and MK-467 (200 μg kg-1 ; MK) were administered IV alone and in combination (R + MK). Levels of sedation and borborygmi were scored. Heart rate (HR), direct arterial blood pressure (ABP) and respiratory rate (fR ) were recorded. Arterial and venous blood gas analyses were performed and venous plasma drug conc...
Gozalo-Marcilla M, Steblaj B, Schauvliege S, Duchateau L, Gasthuys F.Twenty adult healthy horses undergoing elective surgery were involved in this prospective, blinded, clinical study. Horses were randomly allocated to receive a constant rate infusion (CRI) of morphine or dexmedetomidine. After induction, anaesthesia was maintained with isoflurane in oxygen/air and mechanical ventilation applied. The end-tidal isoflurane concentration (FÉISO) was initially set at 0.9% and adjusted by the anaesthetist, to maintain a light surgical plane of anaesthesia, according to an objective flow-chart. The cardiopulmonary function was only minimally different between groups...
Knych HK, Magdesian KG.Equine antimicrobial therapy has advanced over time with the availability of increasing pharmacokinetic and pharmacodynamic studies in horses, allowing for greater evidence-based clinical decision-making. However, many challenges to optimal antimicrobial therapy remain and further research is needed to address these areas. There are a limited number of approved antimicrobials for use in horses, which creates a need for compounded preparations for clinicians. Extra-label drug use is commonplace in equine practice, which warrants continual education of veterinarians about policies and updates. P...
Casoni D, Spadavecchia C, Wampfler B, Thormann W, Levionnois OL.Intravenous anaesthetic drugs are the primary means for producing general anaesthesia in equine practice. The ideal drug for intravenous anaesthesia has high reliability and pharmacokinetic properties indicating short elimination and lack of accumulation when administered for prolonged periods. Induction of general anaesthesia with racemic ketamine preceded by profound sedation has already an established place in the equine field anaesthesia. Due to potential advantages over racemic ketamine, S-ketamine has been employed in horses to induce general anaesthesia, but its optimal dose remains und...
Brightman AH, Manning JP, Benson GJ, Musselman EE.Schirmer I tear tests were conducted on 14 horses. The test was performed before and after IV administration of xylazine hydrochloride, during maintenance anesthesia with halothane in oxygen, and 3 hours after discontinuation of anesthesia. Xylazine hydrochloride did not decrease tear production from the mean base-line value of 23.94 +/- 5.23 mm/min after its IV administration. Tear production was decreased to mean values of 15.57 +/- 4.29 mm/min at 30 minutes and 13.84 +/- 4.25 mm/min at 60 minutes during the maintenance of halothane anesthesia. Three hours after anesthesia was discontinued, ...
Oreff GL, Dahan R, Tatz AJ, Raz T, Britzi M, Kelmer G.To determine the influence of 3 perfusate volumes on amikacin concentration in the metacarpophalangeal joint following cephalic regional limb perfusion (RLP) in standing horses. Methods: Seven healthy horses. Methods: Three perfusate volumes (100, 60, and 30 mL), containing 2 grams of amikacin, were tested during intravenous RLP at the cephalic vein, placing the tourniquet at mid antebrachium, in standing sedated horses. Synovial fluid was collected from the metacarpophalangeal joint before perfusion and at 30 and 120 minutes after perfusion. Serum samples were taken from the jugular vein at t...
Davis JL, Salmon JH, Papich MG.To determine the pharmacokinetics of itraconazole after IV or oral administration of a solution or capsules to horses and to examine disposition of itraconazole in the interstitial fluid (ISF), aqueous humor, and polymorphonuclear leukocytes after oral administration of the solution. Methods: 6 healthy horses. Methods: Horses were administered itraconazole solution (5 mg/kg) by nasogastric tube, and samples of plasma, ISF, aqueous humor, and leukocytes were obtained. Horses were then administered itraconazole capsules (5 mg/kg), and plasma was obtained. Three horses were administered itraconaz...
Berlin S, Randow T, Scheuch E, Grube M, Venner M, Siegmund W.The long-acting azalide antibiotic gamithromycin is marketed for intramuscular treatment of bovine and swine infections. Off-label use in foals leads to severe local lesions likely caused by hyperosmolality of the injected solution. We provide evidence from a pharmacokinetic study in 10 warm-blooded healthy foals for intravenous bolus injection of gamithromycin diluted in distilled water to be a safe and well tolerated alternative. By intravenous dosing, markedly higher plasma exposure and better penetration into bronchoalveolar lavage cells but lower distribution into epithelial lining fluid ...
Burrows GE, Morton RJ, Fales WH.Gram-negative bacterial isolates (635) obtained from routine submissions to the Oklahoma Animal Disease Diagnostic Laboratory during 1983-1987 were tested for antimicrobial susceptibility. Minimal inhibitory concentrations (MICs) were determined for the following antimicrobials using commercially prepared microdilution assay materials: ampicillin, cephalothin, chloramphenicol, erythromycin, gentamicin, kanamycin, oxytetracycline, penicillin G, spectinomycin, sulfachlorpyridazine, sulfadimethoxine, and tylosin. Results for isolates from cattle, dogs, horses, and pigs are presented. In only a fe...
Westermann CM, Laan TT, van Nieuwstadt RA, Bull S, Fink-Gremmels J.To determine whether treatment of horses with antitussive agents before bronchoalveolar lavage (BAL) reduces the frequency and intensity of the cough reflex during BAL. Methods: 8 healthy horses. Methods: Standard BAL was performed on each horse weekly for 6 weeks. Detomidine was used as a general sedative, and various antitussive agents were evaluated for their suitability to suppress undesirable coughing. Treatments administered prior to BAL consisted of saline (0.9% NaCl) solution (control treatment), codeine, butorphanol tartrate, glycopyrrolate, lidocaine hydrochloride (final concentratio...
Kramer CM, Tsang AS, Koenig T, Jeffcott LB, Dart CM, Dart AJ.To survey veterinary practitioners in Australia on how they administer pentosan polysulfate (PPS) to horses and their perceptions of the efficacy of PPS for: the prevention and treatment of osteoarthritis (OA), the treatment of OA when PPS is combined with other drugs, and the efficacy of PPS compared with other disease-modifying osteoarthritic drugs. Methods: Practitioners were contacted by email, which contained a link to an online survey. Results: A total of 76 responses (34.5%) to the survey were received. Respondents most commonly used PPS as prophylactic therapy prior to competition (80....
Fultz L, Giguère S, Berghaus LJ, Grover GS, Merritt DA.Administration of ceftiofur sodium via nebulisation has been recommended for the treatment of bronchopneumonia in horses, despite the lack of pharmacokinetic and safety data. Objective: To compare concentrations of desfuroylceftiofur acetamide (DCA) in plasma and pulmonary epithelial lining fluid (PELF) of foals after nebulisation or i.m. administration of ceftiofur sodium and to determine if nebulisation of ceftiofur sodium induces airway inflammation. Methods: Randomised experimental study. Methods: Six weanling foals received ceftiofur sodium (2.2 mg/kg bwt daily for 5 doses) by the i.m. ...
Mitchell A, Watts AE, Ebetino FH, Suva LJ.Bisphosphonates (BPs) are a family of molecules characterized by two key properties: their ability to bind strongly to bone mineral and their inhibitory effects on mature osteoclasts and thus bone resorption. Chemically two groups of BPs are recognized, non-nitrogen-containing and nitrogen-containing BPs. Non-nitrogen-containing BPs incorporate into the energy pathways of the osteoclast, resulting in disrupted cellular energy metabolism leading to cytotoxic effects and osteoclast apoptosis. Nitrogen-containing BPs primarily inhibit cholesterol biosynthesis resulting in the disruption of intrac...
Wise LN, Ueti MW, Kappmeyer LS, Hines MT, White SN, Davis W, Knowles DP.The equid hemoprotozoan parasite Theileria equi is endemic in most regions worldwide. Infection of horses is a cause of significant economic loss due to costs associated with disease and restriction of trade with non-endemic nations. The ability of certain drugs such as imidocarb dipropionate to eliminate persistent T. equi infection and transmission risk is controversial. The anti-protozoal agent ponazuril has been used successfully to treat equine Sarcosystis neurona and Toxoplasma gondii. The hypothesis that ponazuril inhibits replication of T. equi in vitro was tested. T. equi infected equ...
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...
Landoni MF, Lees P.Pharmacokinetic and pharmacodynamic parameters were established for enantiomers of the non-steroidal anti-inflammatory drug (NSAID) ketoprofen (KTP), each administered separately at a dose level of 1.1 mg/kg to a group of six New Forest geldings, in a three-period cross-over study using a tissue cage model of inflammation. For both S(+)-and R(-)-KTP, penetration into tissue cage fluid (transudate) and inflamed tissue cage fluid (exudate) was rapid, and clearances from exudate and transudate were much slower than from plasma. AUC values were, therefore, higher for exudate and, to a lesser degre...
Anielski P.Doping control of anabolic substances is normally carried out with urine samples taken from athletes and horses. Investigation of alternative specimens, e.g. hair samples, is restricted to special cases, but can also be worthwhile, in addition to urine analysis. Moreover, hair material is preferred in cases of limited availability or complicated collection of urine samples, e.g. from horses. In this work, possible ways of interpretation of analytical results in hair samples are discussed and illustrated by practical experiences. The results demonstrate the applicability of hair analysis to det...
Tappenbeck K, Hoppe S, Reichert C, Feige K, Huber K.The purpose of the study was to compare the contractility-enhancing effects of lidocaine in equine jejunal circular (CSM) and longitudinal smooth muscle (LSM) in vitro. In previous studies, more pronounced effects of lidocaine were observed in ischaemia-reperfusion (IR) injured smooth muscle. Therefore in this study, effects were examined in both non-injured control tissues and tissues challenged by a defined, artificial IR injury. Isometric contractile performance of CSM and LSM, assessed by frequency (F), amplitude (A) and mean active force (MAF) of contractions, was defined as contractility...
Deniau V, Depecker M, Bizon-Mercier C, Couroucé-Malblanc A.To compare the changes in splenic length and thickness and in packed cell volume (PCV) following detomidine or xylazine administration and subsequent epinephrine infusion. Objective: Spleen relaxation occurs following xylazine or detomidine administration and interferes with subsequent splenic contractile response to epinephrine. Methods: Randomized non-blinded crossover experimental study. Methods: 6 healthy adult mares. Methods: The mares received an intravenous (IV) epinephrine infusion (1 μg kg(-1 ) minute(-1) over 5 minutes) one hour after IV administration of detomidine (0.01 mg kg(-1) ...
Bryant JE, Brown MP, Gronwall RR, Merritt KA.The objectives of this study were to determine the pharmacokinetics and tissue concentrations of doxycycline after repeated intragastric administration, and to determine the minimum inhibitory concentrations (MIC) for equine pathogenic bacteria. In experiment 1, 2 mares received a single intragastric dose of doxycycline hyclate (3 mg/kg bwt). Mean peak serum concentration was 0.22 microg/ml 1 h postadministration. In experiment 2, 5 doses of doxycycline hyclate (10 mg/kg bwt), dissolved in water, were administered to each of 6 mares via nasogastric tube at 12 h intervals. The mean +/- s.e. pea...
Mainguy-Seers S, Lavoie JP.Despite substantial research efforts to improve the treatment and outcome of horses with asthma, glucocorticoids (GC) remain the cornerstone of drug treatment of this prevalent disease. The high efficacy of GC to relieve airway obstruction explains their extensive use despite potential deleterious effects. However, much is yet to be uncovered concerning GC use in horses with asthma, including the comparative efficacy of the different drugs, the determination of minimal effective doses and the mechanisms underlying their variable modulation of airway inflammation. The objectives of this structu...
Veronesi F, Fioretti DP, Genchi C.A study was carried out to assess the field efficacy of moxidectin (MOX) against Parascaris equorum in foals. A total of 70 foals from 2 Italian thoroughbred (Farms 1 and 2) stud farms and one trotter stud farm (Farm 3), aged 3-5 months and with faecal egg counts (FEC) f>or=300 eggs per gram (EPG) were included in the study. On each farm, foals were divided into 2 groups (of 10, 8 and 10 foals, respectively) and treated with either moxidectin (MOX, 400 mcg/kg b.w.) or ivermectin (IVM, 200 mcg/kg b.w.) on day 0 and examined for faecal count reduction (FECR) on day 14. Five, 4 and 5 foals, re...
Herdan CL, Acke E, Dicken M, Archer RM, Forsyth SF, Gee EK, Pauwels FE.Three Thoroughbred horses, a 6-week-old filly (Case 1), a 15-year-old broodmare (Case 2) and a yearling filly (Case 3), sustained synovial sepsis secondary to trauma. Results: Case 1 presented with a heel bulb laceration communicating with the distal interphalangeal joint. Arthroscopic lavage was performed and treatment commenced using systemic and local broad spectrum antimicrobial drugs. A pure growth of multi-drug-resistant (MDR) Enterococcus gallinarum was cultured from samples of synovium and joint fluid. Antimicrobial treatment was changed according to the susceptibility results. Respons...
Carstensen H, Hesselkilde EZ, Haugaard MM, Flethøj M, Carlson J, Pehrson S, Jespersen T, Platonov PG, Buhl R.The atrial fibrillatory rate is a potential biomarker in the study of antiarrhythmic drug effects on atrial fibrillation (AF). The purpose of this study was to evaluate whether dose-dependent changes in the atrial fibrillatory rate can be monitored on surface electrocardiography (ECG) following treatment with dofetilide, ranolazine, and a combination of the two in an acute model of AF in horses. Eight horses were subjected to pacing-induced AF on 4 separate days. Saline (control), dofetilide, ranolazine, or a combination of dofetilide and ranolazine was administered in four incremental doses. ...
