The topic of medication in horses encompasses the study and application of pharmaceutical substances used to treat, manage, or prevent diseases and conditions in equine patients. This field involves understanding the pharmacokinetics and pharmacodynamics of various drugs, including their absorption, distribution, metabolism, and excretion in horses. Medications commonly administered to horses include non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, anthelmintics, and sedatives. The appropriate use of these medications is critical for ensuring therapeutic efficacy and minimizing adverse effects. Research in this area focuses on dosage optimization, drug interactions, resistance development, and withdrawal times to ensure both the health of the horse and compliance with regulatory standards. This page aggregates peer-reviewed studies and scholarly articles that explore the pharmacological aspects, clinical applications, and regulatory considerations of equine medications.
Yoxall AT.This paper is an introduction to a series of commissioned articles on therapeutic medicine to be published in Equine Veterinary Journal under differing authorship, during the next 2 years. It presents an account of fundamental concepts common to the use of all drugs and introduces some pharmacokinetic principles to which reference will be made in later articles.
Maylin GA, Rubin DS, Lein DH.A survey of selenium and vitamin E concentrations in horses was conducted at four breeding farms in New York. There were no significant changes in mean blood selenium concentrations in horses at the three sampling dates whereas vitamin E concentrations underwent seasonal fluctuations. The mean blood selenium concentration in this survey for horses fed local feed was 7.7 microgram/dl. Horses fed commercial feed had a mean blood selenium concentration of 15.6 microgram/dl. A 0.94 correlation coefficient was found between blood glutatione peroxidase activity and blood selenium concentrations in h...
Malan FS, Reinecke RK.A single oral dose of fenbendazole (FBZ) at 10 mg/kg body mass was given to 5 donkeys. A further 5 donkeys were dosed with a medicated lick (1 mg FBZ/g lick) until the oral consumption was 10 mg/kg body mass. In both trials FBZ was highly effective against adults of the following genera: Cyathostomum, Cylicocyclus, Cylicostephanus, Cylicodontophorus, Poteriostomum, Cabellonema, Craterostomum and Triodontophorus; similarly high efficiency was obtained against the following species: Habronema majus, Habronema musca, Strongylus vulgaris and Oxyuris equi and worms identified as belonging to the su...
Drudge JH, Lyons ET, Tolliver SC, Kubis JE.The efficacy of oxibendazole given at dose level of 10 mg/kg of body weight was determined by 10 critical tests in foals and by 2 clinical trials in 20 foals (16 treated, 4 nontreated), with special interest in the drug activity against Parascaris equorum. The drug was uniformly efficacious (100%) against P equorum in the 10 critical-test foals, each having between 22 and 236 ascarids. Posttreatment reductions of ascarid egg counts in fecal samples were also 100% in suckling foals treated with oxibendazole given as a drench. Ascarid eggs did not reappear in fecal samples until the 8th week aft...
Bishop WJ.GG is a useful sedative and anaesthetic agent in horses. Used
alone, or in conjunction with barbiturates, it produces a un-
iformly smooth recovery from anaesthesia.
The need to infuse large volumes to obtain the desired effect is
a disadvantage ofthis agent. Few critical studies have been made
on the short and long term effects of administration of GG to
horses. Its pharmacology and clinical use are described and
indicate that it is a safe and useful drug.
Keller H, Hashem A.In a study in the horse, the disposition, the pharmacokinetic parameters and the absorption rates of 3 formulations of phenylbutazone (injection solution, powder and paste suspension) have been determined. After i.v. injection, the half-life time of phenylbutazone has been determined to be 6.6-6.7 h. After oral administration, the absorption of phenylbutazone was found to be faster after administration via stomach tube than after direct application into the mouth. The absorption rat constant of the paste suspension was found to be higher than that of the powder (1.797-2.304 h-1 vs. 0.656-1.197...
Malan FS, Reinecke RK.A single oral dose of fenbendazole (FBZ) at 10mg/kg body mass was given to 5 donkeys. A further 5 donkeys were dosed with a medicated lick (1 mg FBZ/g lick) until the oral consumption was 10mg/kg body mass. In both trials FBZ was highly effective against adults of the following genera: Cyathostomum, Cylicocyelus, Cylicostephanus, Cylicodontophorus, Poteriostomum, Cabellonema, Craterostomum and Triodontophorus; similarly high efficiency was obtained against the following species: Habronema majus, Habronema musca, Strongylus vulgaris and Oxyuris equi and worms identified as belonging to the subf...
Harkins JD, Mundy GD, Stanley S, Woods WE, Sams RA, Richardson DR, Grambow SC, Tobin T.Isoxsuprine is reported to be a peripheral vasodilator used in human and veterinary medicine to treat ischaemic vascular disease. In horses, it is generally administered orally to treat navicular disease and other lower limb problems. To define the scope and duration of its pharmacological responses after oral administration, 6 horses were dosed with isoxsuprine HCl (1.2 mg/kg bwt) q. 12 h for 8 days and then tested to assess the duration and extent of pharmacological actions. There was no significant difference between isoxsuprine and control treatment values for heart rate, spontaneous activ...
Köhler M, Hiepe T.Efficacy of Ivermectin in combating Strongyloides westeri infection of foal. The efficacy of Ivermectin and Mebendazol in combating spontaneous Strongyloides westeri infections in foals has been tested by examining faecal egg output reduction. Ivermectin as a paste formulation was given to sucking foals and pregnant mares in a single dosage of 200 micrograms/kg bodyweight by oral administration. A high efficacy of Ivermectin in combating patent Strongyloides westeri infection could be demonstrated; no side effects have been observed. Mebendazol at a dosage rate of 8 mg/kg did not yield satisfa...
Aljuffali IA, Brainard BM, Moore JN, Kwon S, Allen D, Robertson TP, Arnold RD.The purpose of this study was to determine the pharmacokinetics (PK) of the 5-HT(2A) receptor antagonist ketanserin in healthy adult horses, and to develop a computational model that could be used to optimize dosing. Plasma concentrations of ketanserin were determined using liquid chromatography with mass spectrometry after single and multiple intravenous administration in the horse. A two-compartment linear pharmacokinetic model described the plasma concentration-time profile of ketanserin after single and multiple doses in healthy horses; the terminal half-life was 11.5 h; steady-state volum...
Soliman GA.The pharmacokinetic behaviour of gentamicin sulphate (3.4 mg/kg bwt) was studied following its intramuscular injection to a group of horses and to another group of horses premedicated with sodium methyl arsinate (2 mg/kg bwt) or imidocarb dipropionate (4.8 mg/kg bwt). Considerable differences were observed in the pharmacokinetics of gentamicin in pre-medicated horses and in horses which had received the antibiotic alone. Peak serum concentration of gentamicin (9.85 +/- 0.05 and 11.15 +/- 0.15 micrograms/ml) were attained within 1.45 +/- 0.05 and 0.92 +/- 0.04 h in arsinate and imidocarb-medica...
Hinchcliff KW, Mitten LA.Furosemide and, less commonly, bumetanide and ethacrynic acid are potent diuretics administered to horses for a variety of reasons, including prophylaxis of exercise-induced pulmonary hemorrhage. These drugs affect urine volume and composition, and furosemide has marked effects on plasma volume and composition and on systemic hemodynamics at rest and during exercise.
Sager M.The aim of this article is to emphasize the need for analgesic medication in animals in possibly painful situations, especially in the postoperative period. The two large groups of compounds used as analgesics--the opiates and the nonsteroidal antiinflammatory drugs (NSAIDs)--are described with special reference to their pharmacokinetics, side-effects and toxicity, their mechanism of action, their indications and contraindications. Recommended doses of the different drugs available are given for the dog, the cat, the horse, the swine and the small and large ruminants.
Kollias-Baker C.Analytic chemistry laboratories responding to the concerns of the industry over drug use and abuse in performance horses should continue to develop more sensitive methods of drug detection. The unwanted result of this increase in sensitivity is the detection of therapeutic medications days to weeks after administration. The adoption of decision or threshold concentrations for residues of nonpermitted medications should allow laboratories to focus their efforts on drugs of abuse in the performance horse industries and permit veterinarians to provide appropriate medical care to these equine athl...
