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.
Nannarone S, Gialletti R, Veschini I, Bufalari A, Moriconi F.Alpha-2 agonists are synthetic drugs which cause sedation, analgesia and myorelaxation due to their interaction with alpha-2 adrenoreceptors, widely distributed throughout bodily systems. Because of these actions such drugs are generally used in veterinary practice: to tranquilize animals (pharmacologic restraint) for the safety of both veterinar-ians and cooperators. Such properties facilitate diagnostic examinations or minimally in-vasive and poorly painful surgical procedures, as well as limiting stress factors to the patients. The aim of this study is to find out the minor dosage able to m...
Fuller MC, Abutarbush SM.A 10-year-old gelding was presented with a tongue that had swelled immediately after oral administration of oxfendazole, using an udder infusion cannula. The tongue appeared to have been punctured inadvertently. The horse recovered after treatment with intravenous fluid, antibiotics, and anti-inflammatory drugs. Administering oral medication by this method should be discouraged. Un cheval hongre âgé de 10 ans a été présenté avec une langue devenue tuméfiée immédiatement après l’administration orale d’oxfendazole à l’aide d’une canule à infusion du pis. La langue semblait a...
Gasthuys F, Pockelé K, Vervaet C, Weyenberg W, De Prijck K, Pille F, Vlaminck L, Nelis H, Remon JP.The in vivo behaviour of 5% gentamicin sulphate ocular mini-tablets (2-mm diameter, 6.525 mg weight) was compared with gentamicin eye drops in six ponies. Two mini-tablets were inserted on the bulbar conjunctiva of the right eye while a similar dose of gentamicin was administered via eye drops in the left eye. Irritation induced by the mini-tablets and the eye drops was evaluated using a visual analogue scale (0-10). Tears were sampled with ophthalmologic absorption triangles for 1 min for the determination of the concentration of gentamicin sulphate using a microbiological plate diffusion met...
Bliss G.The Department of Pharmacology at the North Carolina State University College of Veterinary Medicine is currently conducting stability studies of oral suspensions of pergolide for the treatment of Cushing's disease. While those results are not available at this time, this paper summarizes the results of a literature search on possible clinical treatments for equine Cushing's and is intended to provide insight into the pathophysiology of the disease. Pharmacological options for treatment of equine Cushing's are discussed.
Richardson DW, Loinaz R.There is an enormous volume of published material about most of the agents used to treat or prevent arthritis in horses. Unfortunately, most of the claims made by nearly all purveyors of arthritis medications in such media are largely unsubstantiated. In addition, the quality of the available information is highly inconsistent, making evidence-based recommendations difficult. This article concentrates on injectable polysulfated glycosaminoglycan, injectable hyaluronan, and the common oral "nutraceuticals".
Olsén L, Bondesson U, Broström H, Tjälve H, Ingvast-Larsson C.The pharmacokinetics of the histamine H(1)-antagonist cetirizine and its effect on histamine-induced cutaneous wheal formation were studied in six healthy horses following repeated oral administration. After three consecutive administrations of cetirizine (0.2 mg/kg body weight, bw) every 12h, the trough plasma concentration of cetirizine was 16+/-4 ng/mL (mean+/-SD) and the wheal formation was inhibited by 45+/-23%. After four additional administrations of cetirizine (0.4 mg/kg bw) every 12 h, the trough plasma concentration was 48+/-15 ng/mL and the wheal formation was inhibited by 68+/-11%....
White G, McClure SR, Sifferman R, Holste JE, Fleishman C, Murray MJ, Cramer LG.To determine the effects of 8 days of light to heavy exercise on gastric ulcer development in horses and determine the efficacy of omeprazole paste in preventing gastric ulceration. Methods: Randomized, controlled, multicenter clinical trial. Methods: 102 horses with normal-appearing gastric mucosa on endoscopic examination that were in light to heavy training. Methods: Horses at 4 trial locations were allocated into replicates and sham dosed orally (empty syringe) or treated with a paste formulation of omeprazole (1 mg/kg [0.45 mg/ lb], PO) once daily for 8 days. Training regimens varied amon...
Camargo FC, Robinson NE, Berney C, Eberhart S, Baker S, Detolve P, Derksen FJ, Lehner AF, Hughes C, Tobin T.The bronchodilator effects of trimetoquinol (TMQ) have been studied when administered i.v. or intratracheally, but not in an aerosolised form. Objective: To define the relationship between the therapeutic and adverse responses (therapeutic index) of TMQ when administered as an aerosol or by the oral route. Methods: Increasing doses of TMQ were administered to horses with heaves as an aerosol and by the oral route. Dose ranged 100-1000 microg/horse for aerosolised TMQ and from 6-60 microg/kg bwt for the oral route. Airway and cardiac effects were assessed by measurement of maximal change in ple...
Di Concetto S, Michael Archer R, Sigurdsson SF, Clarke K.A pony undergoing elective castration accidentally received an overdose of IV detomidine (200 microg kg(-1)) before anaesthesia was induced with ketamine and midazolam. A further 100 microg kg(-1) IV dose of detomidine was administered during anaesthesia. The mistake was recognized only when the animal failed to recover from anaesthesia in the expected time. The overdose (300 microg kg(-1) in total) was treated successfully with atipamezole, initially given IV and subsequently IM and titrated to effect to a total dose of 1100 microg kg(-1). The pony regained the standing position. A further in...
Aleman M, Gray LC, Williams DC, Holliday TA, Madigan JE, LeCouteur RA, Magdesian KG.Epilepsy is relatively uncommon in horses compared with other species and limited information is available. Objective: The objectives of the study were to describe the age of onset, clinical signs, clinicopathologic data, electroeticephalographic findings, treatment, and outcome, including long-term prognosis in Arabian foals with idiopathic epilepsy. Methods: Twenty-two foals were included in the study. Methods: Medical records from 1985 to 2005 were reviewed. Results: The age of onset of affected foals ranged from 2 days to 6 months. Seizures were characterized by generalized tonic and cloni...
Betbeze CM, Wu CC, Krohne SG, Stiles J.To evaluate the in vitro antifungal properties of silver sulfadiazine (SSD) and natamycin against filamentous fungi isolated from eyes of horses with keratomycosis. Methods: Filamentous fungal isolates obtained from eyes of keratomycosis-affected horses. Methods: Fungal culture of ocular samples yielded 6 Fusarium spp; 7 Aspergillus spp; and 1 isolate each of Curvularia, Scopulariopsis, Penicillium, and Chrysosporium. For each fungal isolate, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SSD and natamycin were determined. Results: For all 17 fungal isolat...
Nogueira SA, Torres SM, Malone ED, Diaz SF, Jessen C, Gilbert S.Imiquimod is an immune response modifier with potent antiviral and antitumour activity. The objective of this pilot study was to evaluate the efficacy of an imiquimod 5% cream (Aldaratrade mark: 3M, Saint Paul, MN, USA) as a topical treatment for equine sarcoids. Fifteen horses with a total of 19 tumours were enrolled, including mixed (7), fibroblastic (5), flat (3), verrucous (2), and nodular (2) types. Baseline data included history, physical examination, tumour location, measurement and digital photography. Imiquimod was applied by the owners three times a week until complete resolution of ...
Bentz BG, Maxwell LK, Erkert RS, Royer CM, Davis MS, MacAllister CG, Clarke CR.The purpose of the study reported here was to describe the bioavailability and pharmacokinetics of acyclovir after intravenous and oral administration to horses. Six healthy adult horses were used in a randomized cross-over study with a 3 x 3 Latin square design. Three treatments were administered to each horse: 10 mg of injectable acyclovir/kg of body weight in 1 L of normal saline delivered as an infusion over 15 minutes; 10 mg of acyclovir/kg in tablets by nasogastric intubation; and 20 mg of acyclovir/kg in tablets by nasogastric intubation. A 2-week washout period was provided between eac...
Rubio-Martínez LM, Cruz AM.Regional limb perfusion involves administration of an antimicrobial solution into the vasculature of a selected portion of the limb that has been isolated from the systemic circulation by controlled application of a tourniquet. The technique provides high antimicrobial concentrations in the region of interest and greatly contributes to the elimination of infection.
Rayner SG, Van Zyl N.To assess the effectiveness of topical mitomycin C application as an alternative adjunctive therapy to CO2 laser ablation in the treatment of equine ocular squamous cell carcinoma. Methods: A retrospective clinical study of eight client owned horses in which 10 affected eyes were treated for ocular squamous cell carcinoma over a 17 month period. (March 2003 to August 2004). Methods: Each horse was given a general anaesthetic to allow CO2 laser ablation of the lesion(s). Mitomycin C at a concentration of 0.4 mg/mL was then applied intraoperatively to the affected areas for 1 or 5 minutes. Posto...
Morsy TA, Salem HS, Haridy FM, Rifaat MM, Abo-Zenadah NY, Adel el-Kadi M.To continue the study on fascioliasis in Tamyia Center, some farm animals were investigated for natural infection with Fasciola species by stool examination. The results showed 40% infection in sheep, 20% in buffalos, 6.7% in donkeys and zero% in horses. The overall percentage of infection was 25.5. The sheep (total dose 1800mg) and the donkey (total dose (4500 mg.) were successfully treated with Mirazid. On the other hand, one buffalo was successfully treated by a total dose 7500mg, the seconds one did not cured, but the eggs deposited per gm markedly decreased.
Snow DH, Baxter P, Whiting B.The pharmacokinetics of meclofenamic acid were studied in Thoroughbred horses and in ponies. After intravenous (i.v.) administration of either 2 mg/kg or 4 mg/kg sodium meclofenamate the elimination half-life was of the order of 0.9 h while the volume of distribution was found to be 0.128 litre/kg. Elimination was in accordance with a one-compartment model. Following oral administration of either meclofenamic acid (4 mg/kg) or sodium meclofenamate (4 mg/kg) a much longer terminal half-life than that calculated for Kel from i.v. data was found. This anomaly indicated that the 'flip-flop' phenom...
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...
This work proposes an application of a minimal complexity physiologically based pharmacokinetic model to predict tramadol concentration vs time profiles in horses. Tramadol is an opioid analgesic also used for veterinary treatments. Researchers and medical doctors can profit from the application of mathematical models as supporting tools to optimize the pharmacological treatment of animal species. The proposed model is based on physiology but adopts the minimal compartmental architecture necessary to describe the experimental data. The model features a system of ordinary differential equations...
Yi R, Zhao S, Kong N, Zhang J, Loganathan D, Mérette S, Morrissey B.γ-Aminobutyric acid is the principal inhibitory neurotransmitter in the central nervous system and regulates the neuronal excitability. There has been anecdotal evidence that γ-aminobutyric acid has been used within a few hours prior to competition in equine sports to calm down nervous horses. However, regulating the use of γ-aminobutyric acid is challenging because it is an endogenous substance in the horse. γ-Aminobutyric acid is usually present at low ng/mL levels in equine plasma; therefore, a sensitive method has to be developed to quantify these low background levels. Measuring low c...
Morén S, Kallberg M, Strom L.Uveitis is common in horses, potentially turning chronic (persistent or recurrent) resulting in impaired vision or blindness. All mainstay therapeutics aims at controlling inflammation, but long-term or lifelong treatment is often needed with possibly severe side effects. Therefore, intravitreal injections with low-dose gentamicin (IVGI) have been used in attempt to give a long-lasting result with potentially less side effects. Objective: To retrospectively assess outcome and long-term complications following one or two low-dose IVGI in Swedish horses with chronic uveitis. Methods: Retrospecti...
Morris J, Hoang D.This article discusses a rare case of isolated xylazine overdose in a human, treated successfully with naloxone. Xylazine, typically used as a veterinary tranquilizer, acts as a potent α2 adrenergic agonist, leading to sedation, muscle relaxation, and potential respiratory depression. In this case, a female mistakenly injected herself with xylazine mistaking it for a different medication. The report discusses naloxone's role beyond opioid overdose, especially regarding substances causing central nervous system (CNS) depression via mechanisms similar to those of opioids. While naloxone is trad...
Shokrollahi S, Mohammadi R, Sarrafzadeh-Rezaei F, Jalilzadeh-Amin G, Hashemi-Asl SM.The aim of this study was to compare the sedative and cardiovascular effects of the combination of xylazine-acepromazine versus xylazine-pregabalin - in horses. Four healthy crossbred horses were included in the study and assigned to two treatments. In treatment I (T1), the animals received xylazine hydrochloride (1.00 mg kg) in combination with acepromazine maleate (0.05 mg kg) intravenously. In treatment II (T2), the animals received intragastric administration of pregabalin (4.00 mg kg) followed by xylazine hydrochloride (1.00 mg kg) intravenously after 60 min. Head height above ground (HHA...
Malalana F.Chemotherapy is the treatment of cancerous cells through the use of cytotoxic drugs. Whilst the use of systemic (intravenous) chemotherapy in equine practice is generally limited to the management of lymphoma, cytotoxic drugs are commonly used in the treatment of accessible skin tumors, either by topical application in the form of ointments or injected intralesionally. These drugs should be employed with caution due to the risk of serious adverse effects. In addition, extreme caution should be followed when preparing, handling, administering, and disposing them, due to their carcinogenic, muta...
Flores L, Hargrave S, Clifford A, Alarcio G, Moeller BC.The abuse of prohibited agents including peptides and basic small-molecule drugs is an area of great concern in horseracing due to their high potential to act as doping agents. These compound classes include agents such as growth hormone-releasing peptides, peptide analgesics, beta-2-adrenergic receptor agonists, and quaternary ammonium drugs that can be challenging to detect and regulate because of their chemical properties and potential rapid elimination following administration. The use of highly sensitive and selective analytical techniques such as liquid chromatography-mass spectrometry (...
Ignacio C, Del Mar LM, Marta B, Sina Z, Vicent R, Aloma MF.In modern times, horses are utilized not only for labour and transportation purposes but also for recreational activities such as competition and pleasure riding. In these various pursuits, the role of vision plays a crucial role. Electroretinography is the most used test to diagnose diseases of the retinal outer segment. There is a wide variety of devices to perform the electroretinography differing one from each other in the corneal electrode and the light stimulation. The Koijman electrode has been tested in dogs but not in horses. The main purpose of this study was to compare electroretino...
CLARKE EG.This research article explores the topic of doping racehorses, looking at the history of the practice, the reasons for it, various methods used, and the substances utilized. It also presents […]
Redpath A, Bowen M.Many cardiac therapeutics lack significant evidence of benefit in the horse, and in many cases their use is based on extrapolation of evidence from other species. In recent years there has been a push to develop a better understanding of both the pharmacodynamics and pharmacokinetics of these drugs. Recent data have described the use of antiarrhythmic agents including sotalol, flecainide, and amiodarone. Data about the use of ACE inhibitors in the management of congestive heart failure are encouraging and support their use in certain cases, wheras evidence for other medicines, such as pimobend...
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...
Messer NT, Arnold K.An 18-year-old Quarter Horse gelding was determined to have immune-mediated hemolytic anemia after detection of autoagglutination of RBC spherocytosis as well as a positive direct Coombs test result. A lack of response to treatment with corticosteroids necessiated the administration of cyclophosphamide and azathioprine. The anemia resolved after treatment with chemotherapeutic drugs.
Light GS, Hellyer PW, Swanson CR.We investigated the influence of parasympathetic tone on the arrhythmogenicity of graded dobutamine infusions in horses anesthetized under clinical conditions. Six horses were used in 9 trials. Two consecutive series of graded dobutamine infusions were given IV; each continuous graded dobutamine infusion was administered for 20 minutes. The dobutamine infusion dosage (5, 10, 15, and 20 micrograms/kg of body weight/min) was increased at 5-minute intervals. Isovolumetric saline solution vehicle (v) or atropine (A; 0.04 mg/kg) was administered IV, or bilateral vagotomy (VG) was performed as a tre...
Nawalinski T, Theodorides VJ.Twenty ponies were allotted to 4 groups of 5 ponies each, and oxibendazole was orally administered at dose levels of 5, 10, 15, and 20 mg/kg. In the 3 groups of ponies given the largest doses, efficacy against 3 species of Strongylus was between 92 and 100% and that against small strongylids of the genera Cyathostomum, Cylicocyclus, Cylicodontophorus, and Cylicostephanus was more than 99%. All adults and 95 to 100% of larvae of the pinworm Oxyuris equi were removed. In the group of ponies given 5 mg/kg, 86 to 100% of the large strongylids and 84 to 100% of the small strongylids were removed, a...
Lacitignola L, Luca P, Santovito R, Comite MSD, Crovace A.Nutritional secondary hyperparathyroidism (NSH) is uncommon in horses. Aim of this report is evaluate an alternative therapeutic approach and provide more information on the diagnostic procedures, through detailed microscopic findings of the bone lesions pony with NSH. Administration of tiludronate along with a balanced diet can be used in a treatment protocol for ponies with NSH. This case report suggests that tiludronate can be used to ameliorate the clinical signs of NSH.
Ingle-Fehr JE, Baxter GM.To quantitate blood flow in the palmar digital artery and dorsal laminae of the hoof in standing, unmedicated, nonsedated horses, and in horses treated with oral isoxsuprine, oral pentoxifylline, and intravenous acetylpromazine as a positive control. Methods: Experimental study; treatments administered in a random cross-over design. Methods: A total of 6 healthy horses selected with at least one nonpigmented forelimb hoof wall and determined to be free of laminitis. Methods: All horses were instrumented with a flow probe placed around one palmar digital artery under general anesthesia and a la...
