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.
Voelter-Ratson K, Monod M, Unger L, Spiess BM, Pot SA.To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland. Methods: Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabouraud's agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detect...
Gilger BC, Stoppini R, Wilkie DA, Clode AB, Pinto NH, Hempstead J, Gerding J, Salmon JH.To describe the use of episcleral silicone matrix cyclosporine (ESMC) drug delivery devices in horses with immune-mediated keratitis (IMMK) with evaluation of tolerability and efficacy in long-term control of inflammation. Methods: Retrospective study. ESMC implants (1.2 cm length, 30% wt/wt cyclosporine (CsA) in silicone; with approximately 2 μg/day steady-state release for at least 400 days) were used. Results: Nineteen horses (20 eyes) received two or more ESMC implants for superficial stromal (n = 9), midstromal (n = 3), or endothelial (n = 5) IMMK. Three additional horses received two or...
Stefanski A, Mevissen M, Möller AM, Kuehni-Boghenbor K, Schmitz A.In this study, we established cell culture conditions for primary equine hepatocytes allowing cytochrome P450 enzyme (CYP) induction experiments. Hepatocytes were isolated after a modified method of Bakala et al. (2003) and cultivated on collagen I coated plates. Three different media were compared for their influence on morphology, viability and CYP activity of the hepatocytes. CYP activity was evaluated with the fluorescent substrate 7-benzyloxy-4-trifluoromethylcoumarin. Induction experiments were carried out with rifampicin, dexamethasone or phenobarbital. Concentration-response curves for...
Nieto JE, Maher O, Stanley SD, Larson R, Snyder JR.To determine the effects of domperidone on in vivo and in vitro measures of gastrointestinal tract motility and contractility in healthy horses. Methods: 18 adult horses and tissue samples from an additional 26 adult horses. Methods: Domperidone or placebo paste was administered to healthy horses in a 2-period crossover study. Gastric emptying was evaluated after oral administration of domperidone paste (1.1 or 5.0 mg/kg) or placebo paste by means of the acetaminophen absorption test in 12 horses. Frequency of defecation, weight of feces produced, fecal moisture, and stomach-to-anus transit ti...
Knych HK, Harrison LM, Casbeer HC, McKemie DS.Methylprednisolone acetate (MPA) is commonly administered to performance horses, and therefore, establishing appropriate withdrawal times prior to performance is critical. The objectives of this study were to describe the plasma pharmacokinetics of MPA and time-related urine and synovial fluid concentrations following intra-articular administration to sixteen racing fit adult Thoroughbred horses. Horses received a single intra-articular administration of MPA (100 mg). Blood, urine, and synovial fluid samples were collected prior to and at various times up to 77 days postdrug administration a...
Rumpler MJ, Colahan P, Sams RA.A simple LC/MSMS method has been developed and fully validated to determine concentrations and characterize the concentration vs. time course of methocarbamol (MCBL) and guaifenesin (GGE) in plasma after a single intravenous dose and multiple oral dose administrations of MCBL to conditioned Thoroughbred horses. The plasma concentration-time profiles for MCBL after a single intravenous dose of 15 mg/kg of MCBL were best described by a three-compartment model. Mean extrapolated peak (C0 ) plasma concentrations were 23.2 (± 5.93) μg/mL. Terminal half-life, volume of distribution at steady-state...
Berghaus LJ, Giguère S, Guldbech K.The objectives of this study were to determine the mutant prevention concentration (MPC), time above the MPC and mutant selection window for 10 antimicrobial agents against Rhodococcus equi and to determine if the combination of a macrolide with rifampin would decrease emergence of resistant mutants. Antimicrobial agents investigated (erythromycin, clarithromycin, azithromycin, rifampin, amikacin, gentamicin, enrofloxacin, vancomycin, imipenem, and doxycycline) were selected based on in vitro activity and frequency of use in foals or people infected with R. equi. Each antimicrobial agent or co...
Barton MH, Paske E, Norton N, King D, Giguère S, Budsberg S.Two firocoxib preparations for oral use are approved for use in animals in many countries: a chewable canine tablet and an equine paste. In order to reduce costs, many veterinarians use the canine product in horses even though this is an off-label use of the preparation. Objective: To determine the relative efficacy of 2 commercially available firocoxib products to inhibit prostaglandin E₂ (PGE2) synthesis after oral dosing in horses. Methods: A crossover design using 8 adult horses (n = 4 for each preparation during each treatment period). Body weight range 532-614 kg. Methods: Horses recei...
Poller C, Hopster K, Rohn K, Kästner SB.Aim of the study was to compare the effect of neuroleptic sedation with acepromazine and neuroleptanalgesia with acepromazine and buprenorphine on thermal thresholds (TT) obtained at the nostrils and at the withers. The study was carried out as a randomized, blinded, controlled trial with cross-over design. Thermal thresholds were determined by incremental contact heat applied to the skin above the nostril (N) or the withers (W). Eleven horses were treated with saline (S), acepromazine (0.05 mg/kg) (ACE) or acepromazine and buprenorphine (0.0075 mg/kg) (AB) intravenously (IV). Single stimula...
Schlusselhuber M, Torelli R, Martini C, Leippe M, Cattoir V, Leclercq R, Laugier C, Grötzinger J, Sanguinetti M, Cauchard J.Rhodococcus equi, the causal agent of rhodococcosis, is a major pathogen of foals and is also responsible for severe infections in immunocompromised humans. Of great concern, strains resistant to currently used antibiotics have emerged. As the number of drugs that are efficient in vivo is limited because of the intracellular localization of the bacterium inside macrophages, new active but cell-permeant drugs will be needed in the near future. In the present study, we evaluated, by in vitro and ex vivo experiments, the ability of the alpha-helical equine antimicrobial peptide eCATH1 to kill int...
Devine EP, KuKanich B, Beard WL.To determine the pharmacokinetics of morphine after IM administration in a clinical population of horses. Methods: Prospective clinical study. Methods: 77 horses. Methods: Morphine sulfate (0.1 mg/kg [0.045 mg/lb], IM) was administered to horses, and blood samples were obtained at predetermined time points. Plasma morphine concentrations were measured via liquid chromatography and mass spectrometry. In preliminary investigations, samples were obtained from 2 healthy horses at 12 time points (up to 12 hours after drug administration) and analyzed via 2-stage pharmacokinetic analysis. In the cli...
Lam G, Zhao S, Sandhu J, Yi R, Loganathan D, Morrissey B.Myo-Inositol tris pyrophosphate (ITPP) is a powerful allosteric modulator of haemoglobin that increases oxygen-releasing capacity of red blood cells. It is capable of crossing the red blood cell membrane unlike its open polyphosphate analog myo-inositol hexakisphosphate (IHP). Systemic administration of ITPP enhanced the exercise capacity in mice. There have been rumours of its abuse in the horse racing industry to enhance the performance of racing horses. In this paper, the detection of ITPP in equine plasma and urine after an administration of ITPP is reported. A Standardbred mare was admini...
López-Sanromán FJ, Holmbak-Petersen R, Varela M, del Alamo AM, Santiago I.To evaluate the duration of effects on movement patterns of horses after sedation with equipotent doses of xylazine hydrochloride, detomidine hydrochloride, or romifidine hydrochloride and determine whether accelerometry can be used to quantify differences among drug treatments. Methods: 6 healthy horses. Methods: Each horse was injected IV with saline (0.9% NaCl) solution (10 mL), xylazine diluted in saline solution (0.5 mg/kg), detomidine diluted in saline solution (0.01 mg/kg), or romifidine diluted in saline solution (0.04 mg/kg) in random order. A triaxial accelerometric device was used f...
Wang CC, Hartmann-Fischbach P, Krueger TR, Wells TL, Feineman AR, Compton JC.Dermorphin and HYP(6) -dermorphin are hepta-peptides and natural opioids originally isolated from the skin of South American frogs. They are more potent than morphine but less likely to produce drug tolerance and addiction. These properties make them ideal candidates for the doping of racehorses to enhance performance during competition. Dermorphin was recently classified as a Class I drug by Racing Commissioners International (RCI), indicating that it is a banned substance in equine athletes. To enforce this ban, a fast and sensitive method was developed for dermorphin and HYP(6)-dermorphin a...
Lee CD, Maxwell LK.In most species, large variations in body size necessitate dose adjustments based on an allometric function of body weight. Despite the substantial disparity in body size between miniature horses and light-breed horses, there are no studies investigating appropriate dosing of any veterinary drug in miniature horses. The purpose of this study was to determine whether miniature horses should receive a different dosage of flunixin meglumine than that used typically in light-breed horses. A standard dose of flunixin meglumine was administered intravenously to eight horses of each breed, and three-...
Cordeiro Rde A, Bittencourt PV, Brilhante RS, Teixeira CE, Castelo-Branco Dde S, Silva ST, De Alencar LP, Souza ER, Bandeira Tde J, Monteiro AJ....Respiratory infections are a common problem among equines and occur with variable rates of morbidity and mortality. Although some fungal species are considered primary agents of respiratory tract infections in several mammals, their relevance in respiratory diseases of equines is frequently neglected. In the present study, we performed an active search for Candida spp. in the nasal cavity of horses. The presence of Candida spp. was investigated through the use of nasal swabs that were streaked on culture media. These yeasts were identified through physiological testing and their in vitro antif...
Hayami A, Darwish WS, Ikenaka Y, Nakayama SM, Ishizuka M.There is little information about drug metabolism and pharmacokinetics in horses. Therefore, it is necessary to characterize the profiles of drug metabolites for the safe use of drugs. In this study, we focused on cytochrome P450 enzymes (CYPs), which represent an important enzyme group to determine pharmacological effects of drugs. We chose diazepam as the drug of choice for this study. The aim of this study was to elucidate the metabolic pathway of diazepam in horses in comparison with rats, and to clarify CYP subfamilies responsible for diazepam metabolism in horses. Our results showed tema...
Bailly-Chouriberry L, Cormant F, Garcia P, Kind A, Popot MA, Bonnaire Y.Cobra venom (Naja kaouthia) contains a toxin called α-cobratoxin (α-Cbtx). This toxin is a natural protein containing 71 amino acids (MW 7821 Da) with a reported analgesic potency greater than morphine. In 2007, in USA, this substance was found in the barns of a thoroughbred trainer and since then till date, the lack of a detection of this molecule has remained a recurring problem for the horseracing industry worldwide. To solve this problem, the first method for the detection of α-cobratoxin in equine plasma has now been developed. Plasma sample (3 mL) was treated with ammonium sulfate at ...
Guan F, Uboh CE, Soma LR, Robinson M, Maylin GA, Li X.Dermorphin is a unique opioid peptide that is 30-40 times more potent than morphine. It was misused and went undetected in horse racing until 2011 when intelligence obtained from a few North American race tracks suggested its use. To prevent such misuse, a reliable analytical method became necessary for detection and identification of dermorphin in post-race horse samples. This paper describes the first liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for such a purpose. Equine plasma and urine samples were pre-treated with ethylenediamine tetra-acetic acid and urea prior to so...
Knych HK, Vidal MA, Casbeer HC, McKemie DS.The use of triamcinolone acetonide (TA) in performance horses necessitates establishing appropriate withdrawal times prior to performance. Objective: To describe the plasma pharmacokinetics of TA and time-related urine and synovial fluid concentrations following i.m. and intra-articular administration to exercised Thoroughbred horses. Methods: Block design. Methods: Twelve racing fit adult Thoroughbred horses received a single i.m. administration of TA (0.1 mg/kg bwt). After an appropriate washout period, the same horses then received a single intra-articular TA administration (9 mg) into the ...
Capolongo F, Gallina G, Fidani M, Baia F, Montesissa C.This study investigated whether a single intra-articular administration (IA) of dexamethasone (DEX) in horses at therapeutic dosage could exert a systemic effect by influencing the hypothalamic-pituitary-adrenal axis activity as a consequence of (limited) absorption and systemic distribution. The results indicated that DEX was detectable in urine collected 12-48 h after IA administration and that injection was accompanied by a reduced urine excretion of cortisol, 6β-hydroxycortisol (6βOHF) and two other metabolites of cortisol lasting up to 48 h post-DEX administration. The systemic effect...
Nieto JE, Maher O, Stanley SD, Knych HK, Snyder JR.To determine the pharmacokinetics, pharmacodynamics, and safety of zoledronic acid in horses. Methods: 8 healthy horses. Methods: A single dose of zoledronic acid (0.057 mg/kg, IV) was administered during a 30-minute period. Venous blood was collected at several time points. Zoledronic acid concentration in plasma was measured by liquid chromatography-tandem mass spectrometry, and pertinent pharmacokinetic parameters were determined. Plasma was analyzed for total calcium, BUN, and creatinine concentrations and a marker for bone resorption (C-terminal telopeptides of type I collagen). Results: ...
Newman JC, Prange T, Jennings S, Barlow BM, Davis JL.The objectives of this study were to examine the pharmacokinetics of tobramycin in the horse following intravenous (IV), intramuscular (IM), and intra-articular (IA) administration. Six mares received 4 mg/kg tobramycin IV, IM, and IV with concurrent IA administration (IV+IA) in a randomized 3-way crossover design. A washout period of at least 7 days was allotted between experiments. After IV administration, the volume of distribution, clearance, and half-life were 0.18 ± 0.04 L/kg, 1.18 ± 0.32 mL·kg/min, and 4.61 ± 1.10 h, respectively. Concurrent IA administration could not be...
Hubbell JA, Kelly EM, Aarnes TK, Bednarski RM, Lerche P, Liu Z, Lakritz J.Midazolam is used to control seizures in horses and to enhance muscle relaxation, but its pharmacokinetics are unknown. Objective: To determine the pharmacokinetics and sedative effects of midazolam in horses. Methods: Blinded, randomised, crossover design. Methods: Midazolam was administered i.v. at either 0.05 or 0.1 mg/kg bwt to 6 horses on 2 occasions at least 7 days apart using a crossover design. Blood samples were collected before and at predetermined times through 24 h after administration. Serum midazolam concentrations were determined by a liquid chromatography tandem-mass spectromet...
Kuroda T, Nagata S, Takizawa Y, Tamura N, Kusano K, Mizobe F, Hariu K.The pharmacokinetics of d-chlorpheniramine (CPM), a histamine H1-receptor antagonist, and its ability to inhibit of histamine-induced cutaneous wheal formation, were studied in healthy Thoroughbred horses (n=5). Following an intravenous (IV) dose of 0.5mg/kg bodyweight (BW), plasma drug disposition was very rapid, with the mean terminal half-life and total body clearance calculated as 2.7h and 0.7 L/h/kg, respectively. The observed maximal inhibition of wheal formation following IV doses of 0.1 and 0.5mg/kg BW were 37.8% and 60.6% at 0.5h, respectively. Oral administration of CPM (0.5mg/kg BW)...
Zozaya H, Gutierrez L, Bernad MJ, Sumano H.Doxycyline (Dox) is a semisynthetic antibacterial drug with pharmacological advantages over its parent drug (tetracycline) in the treatment of various bacterial diseases in horses. Yet, at present a horse-customized pharmaceutical formulation is not available. Based on its pharmacokinetic/pharmacodynamic (PK/PD) ratio, Dox is considered a time-dependent antibacterial drug and ideally expected to achieve sustained plasma drug concentrations both at or slightly above the minimal inhibitory concentration (MIC) level for as long as possible between dosing intervals. Hence, the objective of this st...
Guedes AG, Morisseau C, Sole A, Soares JH, Ulu A, Dong H, Hammock BD.A 4-year old, 500 kg Thoroughbred female horse diagnosed with bilateral forelimb laminitis and cellulitis on the left forelimb became severely painful and refractory to non-steroidal anti-inflammatory therapy (flunixin meglumine on days 1, 2, 3 and 4; and phenylbutazone on days 5, 6 and 7) alone or in combination with gabapentin (days 6 and 7). Methods: Pain scores assessed independently by three individuals with a visual analog scale (VAS; 0 = no pain and 10 = worst possible pain) were 8.5 on day 6, and it increased to 9.5 on day 7. Non-invasive blood pressure monitoring revealed severe hyper...
Donnellan CM, Page PC, Nurton JP, van den Berg JS, Guthrie AJ.Imidocarb, an effective treatment for piroplasmosis, may cause colic and diarrhoea in horses. Atropine and glycopyrrolate are anticholinergics that could reduce the adverse effects of imidocarb. However, atropine and glycopyrrolate inhibit gastrointestinal motility, potentially causing ileus and colic. Objective: To compare glycopyrrolate and atropine in ameliorating the adverse effects of imidocarb dipropionate in horses and to determine the effect of combinations of these drugs on the gastrointestinal tract. Methods: A blinded, randomised, crossover study was performed in 8 healthy horses. E...
Beltaire KA, Cheong SH, Coutinho da Silva MA.Knowledge of commonly encountered fungi infecting the mare's reproductive tract and their respective drug susceptibilities should improve treatment efficacy in mares with fungal endometritis. This is particularly important when practitioners need to start empiric treatment before culture results are complete. Objective: To report the spectrum of fungal isolates from uterine samples from mares with reproductive problems and their respective antifungal susceptibilities. Methods: Equine uterine samples submitted to the Cornell University Animal Health Diagnostic Centre for fungal culture between ...
Kim TW, Della Rocca G, Di Salvo A, Ryschanova R, Sgorbini M, Giorgi M.To determine the pharmacokinetics of cimicoxib and to assess the inhibition of cyclooxygenase (COX) after a 5 mg/kg, single oral administration in horses that were fasted or fed. Methods: The study was conducted using an open, single dose (5 mg/kg), two treatment (fasted and fed), two-period, crossover design with a 2-week interval between dosages. Six healthy mares received 5 mg/kg of cimicoxib via nasogastric tube after fasting for 12 hours, or 2 hours after feeding. After administration, blood samples were collected for up to 24 hours and plasma used for pharmacokinetic analysis. Addi...
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,...
Daniels SP, Proudman CJ.The ovicidal activity of benzimidazole (BZ) anthelmintics is unique and not seen in other drug classes. Such ovicidal efficacy is not widely reported for equine cyathostomins, nor has this activity been tested in the face of BZ resistance. Although the product label states that fenbendazole is for use against BZ-susceptible cyathostomins, susceptibility testing is rarely performed. In this field-based study, the ovicidal efficacy of fenbendazole in horses (n=39) harbouring BZ-resistant cyathostomins was compared when dosed at 7.5mg/kg body weight (BW) orally, as a single dose per os (n=21) or ...
Jarrett MA, Bailey KM, Messenger KM, Prange T, Gaines B, Posner LP.OBJECTIVE To evaluate quality of recovery from general anesthesia in horses after induction with propofol and ketamine versus midazolam and ketamine. DESIGN Prospective randomized crossover study. ANIMALS 6 healthy adult horses. PROCEDURES Horses were premedicated with xylazine (1.0 mg/kg [0.45 mg/lb], IV), and general anesthesia was induced with midazolam (0.1 mg/kg [0.045 mg/lb], IV) or propofol (0.5 mg/kg [0.23 mg/lb], IV), followed by ketamine (3.0 mg/kg [1.36 mg/lb], IV). Horses were endotracheally intubated, and anesthesia was maintained with isoflurane. After 60 minutes, horses were giv...
Ishii H, Shibuya M, So YM, Wong JKY, Ho ENM, Kusano K, Sone Y, Kamiya T, Wakuno A, Ito H, Miyata K, Yamada M, Leung GN.IOX4 is a hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) inhibitor, which was developed for the treatment of anemia by exerting hematopoietic effects. The administration of HIF-PHD inhibitors such as IOX4 to horses is strictly prohibited by the International Federation of Horseracing Authorities and the Fédération Équestre Internationale. To the best of our knowledge, this is the first comprehensive metabolic study of IOX4 in horse plasma and urine after a nasoesophageal administration of IOX4 (500 mg/day, 3 days). A total of four metabolites (three mono-hydroxylated IOX4 and one ...
Linardi RL, Stokes AM, Keowen ML, Barker SA, Hosgood GL, Short CR.To characterize the bioavailability and pharmacokinetics of oral and injectable formulations of methadone after IV, oral, and intragastric administration in horses. Methods: 6 healthy adult horses. Methods: Horses received single doses (each 0.15 mg/kg) of an oral formulation of methadone hydrochloride orally or intragastrically or an injectable formulation of the drug orally, intragastrically, or IV (5 experimental treatments/horse; 2-week washout period between each experimental treatment). A blood sample was collected from each horse before and at predetermined time points over a 360-minute...
Mora-Pereira M, Abarca EM, Duran S, Ravis W, McMullen RJ, Fischer BM, Lee YP, Wooldridge AA.Keratomycosis is a relatively common, sight threatening condition in horses, where treatment is often prolonged and costly. Subconjunctival (SCo) injections offer less resistance to drug diffusion than the topical route, resulting in better penetration to the ocular anterior segment. Voriconazole, a second generation triazole antifungal, is effective against common fungal organisms causing keratomycosis. If combined with a thermogel biomaterial, voriconazole can be easily injected in the SCo space to provide sustained drug release. The purpose of this study was to evaluate the drug concentrati...
Hillyer LL, Ridd Z, Fenwick S, Hincks P, Paine SW.While cobalt is an essential micronutrient for vitamin B synthesis in the horse, at supraphysiological concentrations, it has been shown to enhance performance in human subjects and rats, and there is evidence that its administration in high doses to horses poses a welfare threat. Animal sport regulators currently control cobalt abuse via international race day thresholds, but this work was initiated to explore means of potentially adding to application of those thresholds since cobalt may be present in physiological concentrations. Objective: To devise a scientific basis for differentiation b...
Knych HK, Harrison LM, Casbeer HC, McKemie DS.Methylprednisolone acetate (MPA) is commonly administered to performance horses, and therefore, establishing appropriate withdrawal times prior to performance is critical. The objectives of this study were to describe the plasma pharmacokinetics of MPA and time-related urine and synovial fluid concentrations following intra-articular administration to sixteen racing fit adult Thoroughbred horses. Horses received a single intra-articular administration of MPA (100 mg). Blood, urine, and synovial fluid samples were collected prior to and at various times up to 77 days postdrug administration a...
Turgut K, Sasse HH.The mucociliary tracheal transport rate and clearance index were measured in 16 healthy horses and 16 horses suffering from chronic obstructive pulmonary disease. A marker, Indian ink in syrup, was placed in the mucus layer of the interior wall of the trachea, just in front of the carina, and its displacement was measured after 30 and 60 minutes. The same procedure was repeated 30 minutes after the intravenous administration of 0.8 microgram clenbuterol/kg bodyweight. In the diseased horses the mucociliary transport rate was significantly lower than in the healthy horses. After clenbuterol adm...
Tevell Aberg A, Olsson C, Bondesson U, Hedeland M.This paper describes a study where the metabolism of the non-steroidal anti-inflammatory drug meloxicam was investigated in six horses and in the filamentous fungus Cunninghamella elegans. The metabolites identified were compared between the species, and then the fungus was used to produce larger amounts of the metabolites for future use as reference material. C. elegans proved to be a good model of phase I meloxicam metabolism in horses since all four metabolites found were the same in both species. Apart from the two main metabolites, 5'-hydroxymethylmeloxicam and 5'-carboxymeloxicam, a seco...
Sullivan M, Snow DH.The absorption of orally administered phenylbutazone (5 mg/kg) was studied in 10 thoroughbreds, eight ponies and four pony foals. Large variations in area under the curve (AUC) and peak plasma concentrations were found both within an animal and within groups of animals. Administration of phenylbutazone (5 mg/kg) following an overnight fast resulted in no difference among the three groups of animals with respect to AUC (0 to 24 hours), mean (+/- sd) values of which were 132 +/- 68, 107 +/- 48 and 98 +/- 6, respectively. Absorption characteristics of two oral phenylbutazone preparations (Equipal...
Sierra-Rodriguez T, Groover ES, Lascola KM, Mora-Pereira M, Lee YH, Duran SH, Ravis WR, Spangler E, Hathcock T, Wooldridge AA.Voriconazole (VRC) is a potential treatment for pneumomycosis in horses. The objectives of this study were to determine if the delivery of Vfend using a Flexineb nebulizer produced clinically significant [VRC] in lower airways. The hypothesis was that [VRC] after delivery by nebulization would be greater in the pulmonary epithelial lining fluid than plasma. A secondary objective was to determine [VRC] in upper airways through the collection of nasopharyngeal wash (NPW) samples. Voriconazole solution [Vfend-6.25 mg/mL, 100 (n = 2), 200 (n = 3), 500 (n = 1) mg] was nebulized once in 6 health...
Tou K, Cawley A, Bowen C, Sornalingam K, Fu S.The conventional detection of exogenous drugs in equine doping samples has been used for confirmation and subsequent prosecution of participants responsible. In recent years, alternative methods using indirect detection have been investigated due to the expanding number of pharmaceutical agents available with the potential of misuse. The monitoring of endogenous biomarkers such as hydrocortisone (HC) has been studied in equine urine with an international threshold of 1 μg/ml established; however, there is no current threshold for equine plasma. The aim of this research was to investigate pl...
Langston VC, Fontenot RL, Byers JA, Andrews CM, Mochal-King CA.The objective of this study was to determine the pharmacokinetics of meropenem in horses after intravenous (IV) administration. A single IV dose of meropenem was administered to six adult horses at 10 mg/kg. Plasma and synovial fluid samples were collected for 6 hr following administration. Meropenem concentrations were determined by bioassay. Plasma and synovial fluid data were analyzed by compartmental and noncompartmental pharmacokinetic methods. Mean ± SD values for elimination half-life, volume of distribution at steady-state, and clearance after IV administration for plasma samples ...
Kuroda T, Minamijima Y, Nomura M, Yamashita S, Yamada M, Nagata S, Mita H, Tamura N, Fukuda K, Kuwano A, Kusano K, Toutain PL, Sato F.For medication control in several jurisdictions, withdrawal time is the period of refrain from racing after drug administration. It is set by adding a safety period to an experimental detection time. However, there are no reports of statistical analyses of detection time for the determination of withdrawal time in flunixin meglumine-treated horses. Objective: To analyse the population pharmacokinetics of flunixin in horses through the generation of a dataset for detection time statistical analysis and predictions via Monte Carlo simulation. Methods: Experimental study. Methods: Drug plasma and...
Amaral A, Fernandes C, Szóstek-Mioduchowska A, Rebordão MR, Skarzynski DJ, Ferreira-Dias G.Endometrosis is a reproductive pathology that is responsible for mare infertility. Our recent studies have focused on the involvement of neutrophil extracellular traps enzymes, such as elastase (ELA), in the development of equine endometrosis. Noscapine (NOSC) is an alkaloid derived from poppy opium with anticough, antistroke, anticancer, and antifibrotic properties. The present work investigates the putative inhibitory in vitro effect of NOSC on collagen type I alpha 2 chain () mRNA and COL1 protein relative abundance induced by ELA in endometrial explants of mares in the follicular or mid-lu...
Stieler AL, Sanchez LC, Mallicote MF, Martabano BB, Burrow JA, MacKay RJ.The mechanism of hyperthermia, a potentially fatal adverse effect of erythromycin treatment of foals, is unknown. Objective: To determine the cause of erythromycin-associated hyperthermia. It was hypothesised that the normal sweat response of foals is impaired by treatment with erythromycin. Methods: Blinded, crossover study in 10 healthy pony foals. Methods: Foals kept in stalls were given either erythromycin (25 mg/kg bwt orally, 3 times daily) or control for 10 days then turned out for a further 10 days. Quantitative intradermal terbutaline sweat tests were performed on Days 1 (baseline)...
Sykes BW, Underwood C, Greer R, McGowan CM, Mills PC.Omeprazole is widely used in the treatment of equine gastric ulcer syndrome. To date, little is known about the relative pharmacokinetics of the different formulations making comparisons between products difficult. The objectives of the study were to investigate the relative pharmacokinetics of five commercially available formulations of omeprazole in the horse and to test for bioequivalence of four of the formulations using one of the formulations as a reference standard. Twelve mature Thoroughbred horses were fasted for 16 h then administered 2 g of each formulation in a cross-over design. S...
Teixeira Neto FJ, McDonell WN, Black WD, Duronghphongtorn S.To evaluate cardiopulmonary effects of glycopyrrolate in horses anesthetized with halothane and xylazine. Methods: 6 horses. Methods: Horses were allocated to 2 treatment groups in a randomized complete block design. Anesthesia was maintained in mechanically ventilated horses by administration of halothane (1% end-tidal concentration) combined with a constant-rate infusion of xylazine hydrochloride (1 mg/kg/h, i.v.). Hemodynamic variables were monitored after induction of anesthesia and for 120 minutes after administration of glycopyrrolate or saline (0.9% NaCl) solution. Glycopyrrolate (2.5 m...
Smiet E, Haritova A, Heil BA, Fink-Gremmels J, Wijnberg ID.To compare the pharmacokinetics of the fourth generation cephalosporin, cefquinome, in neonatal foals, 6-week-old foals and mature New Forest ponies in order to recommend appropriate dosage regimens for use of this drug. Methods: Cefquinome was administered i.v. at 1 mg/kg bwt twice a day (q. 12 h), 1 mg/kg bwt 3 times a day (q. 8 h) or 4.5 mg/kg bwt q. 12 h to each age group (n = 6). Plasma cefquinome concentrations were analysed using high-performance liquid chromatography combined with electrospray tandem mass spectrometry. Results: Both foal age groups had comparable pharmacokinetic data e...
Sanchez LC, Murray MJ, Merritt AM.To evaluate the efficacy of omeprazole paste, a commonly used antiulcer drug, on intragastric pH in clinically normal neonatal foals. Methods: 6 clinically normal foals between 5 and 14 days of age. Methods: Intragastric pH was recorded in each foal by use of a disposable antimony pH electrode with internal reference. Values for intragastric pH were recorded every 4 seconds by use of an ambulatory pH monitor. There were two 24-hour recordings of intragastric pH for each foal, with 24 hours between recordings. Foals were not administered any drugs during the first recording. Foals were administ...
Yamada M, Kinoshita K, Kurosawa M, Saito K, Nakazawa H.Nandrolone (17beta-hydroxy-4-estren-3-one, NAD) is an endogenous steroid hormone; thus, the detection of its metabolites is not conclusive of NAD doping in racehorses. NAD doping control in male horses is based on the threshold, namely, the concentration ratio of 5alpha-estran-3beta,17alpha-diol (ETA) to 5(10)-estren-3beta,17alpha-diol (ETE). The ETA/ETE ratio of 1/1 was determined based on statistical data of authentic horses in International Federation of Horseracing Authorities. To individuals with complex metabolic disorders, however, such a threshold might not be applicable. The aim of th...
Godfrey JL, Hardy J, Cohen ND.OBJECTIVE To evaluate the effect of volume of IV regional limb perfusion (IVRLP) on amikacin concentrations in synovial and interstitial fluid of horses. ANIMALS 8 healthy adult horses. PROCEDURES Each forelimb was randomly assigned to receive IVRLP with 4 mL of amikacin sulfate solution (250 mg/mL) plus 56 mL (total volume, 60 mL) or 6 mL (total volume, 10 mL) of lactated Ringer solution. Horses were anesthetized, and baseline synovial and interstitial fluid samples were collected. A tourniquet was placed, and the assigned treatment was administered via the lateral palmar digital vein. Venous...
Guedes AGP, Tearney CC, Cenani A, Aristizabal F, Nieto J.To compare postanesthetic xylazine and dexmedetomidine on recovery characteristics from sevoflurane anesthesia in horses. Methods: Randomized, crossover study. Methods: Six geldings, mean±standard deviation (SD) (range), 17±4 (11-24) years and 527±80 (420-660) kg. Methods: Horses were anesthetized with sevoflurane for 60 minutes under standardized conditions for a regional limb perfusion study. In recovery, horses were administered either xylazine (200 μg kg) or dexmedetomidine (0.875 μg kg) intravenously. Recoveries were unassisted and were video-recorded for later evaluation of rec...
Diamond MJ, Young LE, Bartram DH, Gregg AS, Clutton RE, Long KJ, Jones RS.Romifidine, 100 micrograms/kg administered by intravenous injection, was evaluated as a premedicant to ketamine/halothane anaesthesia in 60 horses. Sedation developed within one to two minutes. In three cases mild staggering occurred within two minutes. Anaesthesia was induced after five minutes by the intravenous administration of ketamine (2 to 2.2 mg/kg). A mean time of 79 seconds elapsed before lateral recumbency was adopted. Fifty-four of the horses sank smoothly to the floor, with occasional steps sideways. Jaw tone, limb rigidity and mild muscle tremors often persisted for short periods...
DiPietro JA, Todd KS.The common anthelmintics used to treat parasitic infections of horses are described. Dosage, anthelmintic spectrum, formulation and administration, mode of action, toxicity contraindications, and resistance of parasites to anthelmintics are included.
Henrikson SL, Rush BR.To determine the onset, magnitude, and duration of bronchodilation after administration of aerosolized salmeterol xinafoate in horses with recurrent airway obstruction. Methods: Randomized controlled study Methods: 6 horses with recurrent airway obstruction. Procedure Horses received aerosolized salmeterol (210 microg) or no treatment, using a crossover design. Salmeterol was administered, using a mask designed for aerosol delivery in horses. Subjective rating of airway obstruction (RAO), maximal change in pleural pressure (deltaPplmax), and pulmonary resistance (RL) were determined at baselin...
Soma LR, Rudy JA, Uboh CE, Xu F, Snapp HM.To investigate the pharmacokinetics and behavioral effects of aminorex administered IV and PO in horses. Methods: 7 Thoroughbreds. Methods: In a cross-over design, aminorex (0.03 mg/kg) was administered IV or PO. Plasma and urinary aminorex concentrations were determined via liquid chromatography- mass spectrometry. Results: Decrease of aminorex from plasma following IV administration was described by a 3-compartment pharmacokinetic model. Median (range) values of alpha, beta, and gamma half-lives were 0.04 (0.01 to 0.28), 2.30 (1.23 to 3.09), and 18.82 (8.13 to 46.64) hours, respectively. Tot...
Duncan JL, Abbott EM, Arundel JH, Eysker M, Klei TR, Krecek RC, Lyons ET, Reinemeyer C, Slocombe JO.These guidelines have been designed to assist in the planning, operation and interpretation of studies which would serve to assess the efficacy of drugs against internal parasites of horses. Although the term anthelmintic is used in the title and text, these guidelines include studies on drug efficacy against larvae of horse bot flies, Gasterophilus spp., which are non-helminth parasites commonly occurring in the stomach of horses. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on selection of animals, housing, feed, d...
