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Topic:Drug
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.
A comparison of injectable anaesthetic regimens in Mammoth asses. Xylazine (1.1 mg/kg body weight [bwt])-ketamine (2.2 mg/kg bwt) (X/K) anaesthesia was evaluated, in nine Mammoth asses, for effectiveness and compared with two other injectable anaesthetic combinations: xylazine (1.1 mg/kg bwt)-butorphanol (0.044 mg/kg bwt)-ketamine (2.2 mg/kg bwt) (X/B/K); and xylazine (1.1 mg/kg bwt)-tiletamine-zolazepam (1.1 mg/kg bwt) (X/T). All drugs were given intravenously (i.v.). Heart rate, respiratory rate, systolic blood pressure, arterial blood pH, PCO2, PO2, recumbency time and number of attempts to stand were measured. Quality of induction and recovery, muscle re...
The effects of famotidine, ranitidine and magnesium hydroxide/aluminium hydroxide on gastric fluid pH in adult horses. Gastric fluid pH was measured in five adult horses following nasogastric administration of famotidine, 0.5, 1.0, and 2.0 mg/kg bodyweight (bwt); ranitidine, 4.4 and 6.6 mg/kg bwt and an antacid containing magnesium hydroxide (40 mg/ml) and aluminium hydroxide (45 mg/ml), 120 and 180 ml. Fluid was aspirated through a 16 French nasogastric feeding tube at 15 min intervals, and pH was measured using a pH meter. Basal gastric fluid pH was measured at 20 min intervals for 6 h in each horse and, with the exception of two measurements of 4.66 and 4.17, ranged from 1.42 to 2.41, with a mean pH of 1.88...
Pharmacokinetics and metabolism of intravenous doxapram in horses. The pharmacokinetics and metabolism of doxapram in horses administered intravenous (iv) doses of 0.275, 0.55 and 1.1 mg doxapram/kg bodyweight (bwt) were investigated. Plasma doxapram concentrations decreased rapidly after drug administration and the disappearance of doxapram from plasma was best described by a polyexponential equation. Median values of total body clearance were 10.9, 10.6 and 10.9 ml/min/kg bwt for the three doses and were independent of dose. The steady-state volume of distribution was approximately 1,200 ml/kg bwt and the median biological half-life ranged from 121 to 178 m...
Cardiovascular effects of dopexamine HCl in conscious and halothane-anaesthetised horses. The cardiovascular effects of serial increasing infusions of dopexamine HCl were investigated in six conscious (1, 2, 4, 6, 10 micrograms/kg bodyweight [bwt]/min) and eight (0.5, 1, 5, 10, 20 micrograms/kg bwt/min) halothane-anaesthetised horses. Dopexamine produced dose-dependent increases in heart rate, +dP/dtmax' -dP/dtmax and cardiac output, and a decrease in systemic vascular resistance in conscious and halothane-anaesthetised horses. Mean arterial blood pressure did not change in conscious horses but increased to a maximum value at 10 micrograms/kg bwt/min in halothane-anaesthetised hors...
The spectrum of antibiotic resistance in human and veterinary isolates of Escherichia coli collected from 1984-86 in northern India. This study was undertaken to assess the spectrum of drug resistance prevalent in Escherichia coli isolates from human and animal populations in Northern India. Three hundred and two isolates of Escherichia coli isolated from various infections of humans (47 from diarrhoea; 101 from urinary tract infection) and veterinary animals (17 from poultry septicaemia; 75 from bovine diarrhoea; 14 from ovine diarrhoea and 48 from equine metritis) were studied for their susceptibility to ampicillin, cephaloridine, amoxycillin, cloxacillin, oxytetracycline, doxycycline, chloramphenicol, gentamicin, and tri...
Identification of a tolfenamic acid metabolite in the horse by gas chromatography-mass spectrometry. A tolfenamic acid metabolite, a hydroxylated product, has been identified in equine plasma and urine samples using gas chromatography-mass spectrometry in the electron-impact and chemical-ionization modes. The method also allows the qualitative monitoring of the elimination of the drug and its metabolites from plasma. The two compounds are detected up to 48 and 24 h, respectively, after a single oral administration of a 30 mg/kg dose. The simultaneous detection of the two products increases the reliability of anti-doping control analysis.
Solid-phase extraction techniques for the determination of glycopyrrolate from equine urine by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry. Glycopyrrolate (Robinul) is a quaternary ammonium salt which serves as a respiratory enhancing drug. It is reportedly used in horse racing to improve breathing. Extraction of glycopyrrolate from equine urine employing unique solid-phase extraction techniques gave a residue suitable for liquid chromatography-tandem mass spectrometry (LC-MS-MS) and gas chromatography-mass spectrometry (GC-MS). LC-MS-MS analysis employed an extract derived from 5 ml of urine subjected to cation-exchange chromatography. The daughter ion of m/z 318 monitored in the positive-ion mode was m/z 116. Recovery of glycopy...
Equine piroplasmosis: a review. This review focuses on equine piroplasmosis with specific reference to its distribution, diagnosis and clinical and pathological signs. The more common used drugs are discussed both with reference to treatment and chemosterilization. Areas requiring further research are also briefly mentioned.
The pharmacokinetics of a slow-release theophylline preparation in horses after intravenous and oral administration. The pharmacokinetics of a slow-release theophylline formulation was investigated following intravenous and oral administration at 10 mg/kg in horses. A tricompartmental model was selected to describe the intravenous plasma profile. The elimination half-life (t1/2 beta) was 16.91 +/- 0.93 h, the apparent volume of distribution (Vd) was 1.35 +/- 0.18 L/kg and the body clearance (ClB) was 0.061 +/- 0.009 L kg-1 h. After oral administration the half-life of absorption was 1.24 +/- 0.30 h, and the calculated bioavailability was above 100%. The t1/2 beta after oral administration was 18.51 +/- 1.75 ...
Ketamine, Telazol, xylazine and detomidine. A comparative anesthetic drug combinations study in ponies. This study was designed to assess the effects of 5 anesthetic drug combinations in ponies: (1) ketamine 2.75 mg/kg, xylazine 1.0 mg/kg (KX), (2) Telazol 1.65 mg/kg, xylazine 1.0 mg/kg (TX), (3) Telazol 2 mg/kg, detomidine 20 micrograms/kg (TD-20), (4) Telazol 2 mg/kg, detomidine 40 micrograms/kg (TD-40), (5) Telazol 3 mg/kg, detomidine 60 micrograms/kg (TD-60). All drugs were given iv with xylazine or detomidine preceding ketamine or Telazol by 5 min. Heart rate was decreased significantly from 5 min to arousal after TD-20 but only at 60 and 90 min after TD-40 and TD-60 respectively. Respirato...
Furosemide-induced changes in plasma and blood volume of horses. The effect of furosemide administration (1 mg/kg body weight, i.v.) on plasma and blood volumes in 6 intact and 4 splenectomized horses was measured using Evans blue dye dilution, hematocrit, and hemoglobin and plasma total solids concentrations. Body weight decreased by 33.6 +/- 3.3 and 33.7 +/- 0.8 g/kg 4 h after furosemide administration to intact and splenectomized mares, respectively. Plasma volume, estimated by Evans blue dye dilution, was reduced by 8.3 +/- 3.3% (mean +/- SE) 4 h after furosemide administration. The reduction in plasma volume was first detectable 5-10 min after furosemi...
Chemical restraint for surgery in the standing horse. Chemical restraint can be a useful pharmacologic tool to assist the veterinarian performing surgery in the standing horse. The agents discussed impose minimal adverse side effects and are considered relatively safe when administered in the doses described. Acetylpromazine, the most widely used tranquilizer, produces mild sedation but no analgesia. The use of tranquilizers for surgical procedures requires the combined use of either a local anesthetic technique or a sedative-hypnotic or opiate to provide analgesia. Sedative-hypnotics such as xylazine and detomidine or opiates such as morphine an...
Comparison of the sedative effects of medetomidine and xylazine in horses. The sedative effects in horses of the new alpha 2 agonist medetomidine were compared with those of xylazine. Four ponies and one horse were treated on separate occasions with two doses of medetomidine (5 micrograms/kg bodyweight and 10 micrograms/kg bodyweight) and with one dose of xylazine (1 mg/kg bodyweight) given by intravenous injection. Medetomidine at 10 micrograms/kg was similar to 1 mg/kg xylazine in its sedative effect but produced more severe and more prolonged ataxia, and one animal fell over during the study. Medetomidine at 5 micrograms/kg produced less sedation but a similar deg...
Pharmacologic treatment of priapism in two horses. Benztropine mesylate was used successfully to treat priapism that developed during anesthesia in 2 horses. After IV injection, there was a rapid resolution of signs in both horses, and no side effects were observed. The choice of an effective method to treat priapism is challenging because precise causes in most patients have not been well-defined. Benztropine mesylate is a synthetic compound resulting from the combination of the active portions of atropine and diphenhydramine, and is believed effective because of its central acetyl-choline-antagonizing properties.
Morphine and etorphine: XIV. Detection by ELISA in equine urine. We have raised antibodies to morphine and etorphine and developed one-step enzyme-linked immunosorbent assays (ELISA) for these drugs as part of a panel of post race tests for drugs in racing horses. These tests are simple, can be completed in 2 h, and can be read by visual inspection. The morphine ELISA has an I50 for morphine of about 1.5 ng/mL, while the etorphine ELISA has an I50 for etorphine of 250 pg/mL. Cross-reactivity studies show that the antimorphine antibody cross-reacts well with levorphanol, hydromorphone, and oxycodone, while the anti-etorphine antibody showed no cross-reactivi...
Analgesic and spasmolytic effects of dipyrone, hyoscine-N-butylbromide and a combination of the two in ponies. The analgesic and spasmolytic effects of dipyrone (Novalgin) (2500 mg/100 kg bodyweight) hyoscine-N-butylbromide (Buscopan) (20 mg/100 kg bodyweight) and a combination of both drugs were evaluated in a balloon-induced model of colic, using five ponies with caecal fistulae. The drugs were given intravenously and 0.9 per cent sodium chloride solution (5 ml/100 kg bodyweight) was used as a control. The physiological saline solution and dipyrone had no effect on caecal contractions. After the injection of hyoscine-N-butylbromide and the drug combination caecal contractions ceased within 30 seconds...
Influence of digoxin followed by dopamine on the cardiovascular depression during a standard halothane anaesthesia in dorsally recumbent, ventilated ponies. The influence of digoxin (0.01 mg/kg) given as an intravenous bolus followed by dopamine at different infusion rates (1.25, 2.5 and 5.0 micrograms/kg/min) on the cardiovascular depression during a standard halothane anaesthesia was studied in dorsally recumbent ventilated ponies. Preanaesthetic digitalization induced no clear positive cardiovascular effects over 30 minutes, except for non-significant increases in mean pulmonary artery pressure and total pulmonary resistance. These changes were probably time-related. No specific side-effects related to the fast intravenous digitalization were n...
The prevalence of anthelmintic resistance of horse strongyles in The Netherlands. A survey to determine the prevalence of anthelmintic resistance of horse strongyles was carried out with 616 horses on 22 farms. The tested drugs were cambendazole, pyrantel pamaote and ivermectin. Based on egg count reduction tests the efficacy of cambendazole varied from 0% to 93% and of pyrantel from 93% to 100%. Ivermectin treatments were 100% effective on all farms. Larval cultures after cambendazole treatments revealed exclusively cyathostome larvae. After pyrantel treatments besides cyathostome larvae other types of larvae were also found. After ivermectin treatments only a few cyathost...
The pharmacokinetics and locomotor activity of alfentanil in the horse. The pharmacokinetics of alfentanil were investigated in the horse. Four doses of alfentanil (4, 10, 20 and 40 micrograms/kg) were given to four horses at different times and their locomotor activity monitored. Doses of 20 and 40 micrograms/kg produced a significant increase in locomotor activity. The plasma concentrations of alfentanil were measured in six standing horses and the pharmacokinetics calculated. It was found that the decay curves were best described by a biexponential equation. The elimination half-life (t1/2 beta) was 21.65 +/- 3.99 min and the clearance (Cl) was 14.1 +/- 0.7 ml/...
Studies of meclofenamic acid and two metabolites in horses–pharmacokinetics and effects on exercise tolerance. The pharmacokinetics and the effects on treadmill exercise of the anti-inflammatory drug meclofenamic acid were studied in seven Standardbred horses after single intravenous and/or oral doses. The decline in plasma concentration after a single intravenous dose of meclofenamic acid (2.2 mg/kg b.wt) was described by a two-compartment open model. The average elimination half-life was 1.4 h, the apparent volume of distribution 0.14 l/kg and the plasma clearance 0.12 l/h kg. Absorption was the rate-limiting step after oral administration. Non-compartmental analysis showed a mean absorption time of ...
Detection of reserpine in horses by high-performance liquid chromatography. A high-performance liquid chromatography (HPLC) assay was developed for the detection of reserpine. The assay was used to monitor the plasma concentrations of the drug given intramuscularly on one or two occasions to five horses. The blood concentrations of reserpine varied quite considerably between horses given the same dose of the drug. However, on average, reserpine could be detected consistently, and quantified, for 48 h after a single dose of 2.5 mg, and for a similar period after the second of two 2.5 mg doses given 13 d apart. Because of the apparently large variability in the pharmaco...
[A liposomal form of diamidine: reduced toxicity]. The cultures of Nuttalia eque mainly develop in the reticuloendothelial organs and so in treatment of nuttaliosis in horses and the Nuttalia carriers diamidine, an analog of imidocarb or imidozoline, was used encapsulated in liposomes. The liposomes were prepared with a modification of the phase inversion method (the lipids were dissolved in a mixture of freon-11 and chloroform). The content of the organic solvents in the preparation, as evidenced by gas liquid chromatography, was less than 0.2 per cent. The main fraction consisted of particles 1.5 to 2.5 microns in diameter. The tests on anim...
Resistance of population-B equine strongyles to thiabendazole, oxfendazole, and phenothiazine (1981 to 1987). Critical tests were completed on foals (n = 15) naturally infected with benzimidazole (BZ)-resistant population-B strongyles during the period between 1981 and 1987. Thiabendazole at a dosage of 44 mg/kg was tested in 8 foals, oxfendazole at 10 mg/kg was tested in 4 foals, and phenothiazine at 55 mg/kg, cambendazole at 20 mg/kg, and fenbendazole at 5 mg/kg were tested in 1 foal each. Efficacies of thiabendazole, cambendazole, and fenbendazole against the 5 species of BZ-resistant small strongyles (Cyathostomum catinatum, Cyathostomum coronatum, Cylicocylus nassatus, Cylicostephanus goldi, and ...
Effects of detomidine on equine oesophageal function as studied by contrast radiography. The effects of sedation with detomidine on oesophageal function were assessed by contrast radiography in 10 healthy adult thoroughbred horses. Barium swallows were monitored by means of image intensification, first without sedation and then after the intravenous administration of detomidine at doses of 10 and 20 micrograms/kg bodyweight. The transit time of contrast agent to the oesophageal hiatus was recorded and each swallow was scored for markers of oesophageal dysfunction. Analysis of the data indicated that there were highly significant dose dependent increases in the transit time, the re...
Pharmacokinetic, biochemical and tolerance studies on carprofen in the horse. Carprofen, a non-steroidal anti-inflammatory drug (NSAID) was administered to three Thoroughbred geldings and three Shetland ponies to determine its plasma disposition and tolerance. The main pharmacokinetic characteristics of carprofen in horses and ponies were a volume of distribution of 0.08 to 0.32 litres/kg (mean +/- se = 0.23 +/- 0.04) a systemic clearance of 26.4 to 78.5 ml/min (mean +/- se = 44.9 +/- 8.0) and a plasma elimination half-life of 14.5 to 31.4 h (mean +/- se = 21.9 +/- 2.3). There was no evidence of any accumulation of carprofen in plasma when the drug was given orally at a...
A comparison of injectable anesthetic combinations in horses. Six combinations of injectable anesthetic agents were administered to six adult horses in a Latin square design. The drug combinations were xylazine-ketamine, xylazine-butorphanol-ketamine, xylazine-tiletamine-zolazepam, xylazine-butorphanol-tiletamine-zolazepam, detomidine-ketamine, and detomidine-butorphanol-ketamine. Measured variables were heart rate, respiratory rate, systolic blood pressure, arterial pH (pHa), PaCO2, PaO2, recumbency time, and number of attempts necessary to stand. Quality of induction and recovery, muscle relaxation, and response to stimulus were evaluated subjectively....
Isolation of equine herpesvirus-1 mutants in the presence of (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine: demonstration of resistance in vitro and in vivo. The compound (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (HPMPA) had been previously shown to be highly effective in treatment of EHV-1 in a murine model for the equine disease. This paper describes the isolation of a series of mutants resistant to the drug. Resistance was demonstrated in cell culture and one mutant was tested in a murine model. The resistant mutant was pathogenic for mice; infectious virus was recovered from respiratory tissues and blood at levels similar to the parental virus. However, the mutant showed a significant degree of resistance in vivo, thus proving the viru...
Comparison of the efficacy of ivermectin, oxibendazole, and pyrantel pamoate against 28-day Parascaris equorum larvae in the intestine of pony foals. Sixteen helminth-free pony foals were inoculated with a mean (+/- SD) 2,000 (+/- 545.5) infective Parascaris equorum eggs (day 0). Foals were allocated to replicates of 4, and treatments within each replicate were assigned at random. Treatment administered on postinoculation day (PID) 28 included no treatment (control), 0.2 mg of ivermectin/kg of body weight, 10 mg of oxibendazole/kg, or 6.6 mg of pyrantel base (pamoate)/kg. Paste formulations of the anthelmintics were administered orally. The foals were euthanatized 14 days after treatment (PID 42) and examined for P equorum larvae in the sma...
Disposition of human drug preparations in the horse. I. Rectally administered indomethacin. A high-performance liquid chromatographic method to measure urinary indomethacin levels is described. In 0.5 ml urine, 1 micrograms/ml of indomethacin could be detected. Alkaline hydrolysis of urine resulted in the decomposition of indomethacin. When two suppositories of Indocid corresponding to 200 mg indomethacin were administered rectally to four horses the drug was rapidly absorbed and remained detectable in urine from 1 to 12 h. The excretion rate peaked after 2-3 h while the maximal concentration ranged from 18.5 to 80.6 micrograms/ml. Only 8 to 16% of the indomethacin dose was eliminate...
