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.
Jargielo MM, Kritchevsky JE, Bertin FR.Pergolide, labeled for the treatment of pituitary pars intermedia dysfunction, is 90% protein bound and might cause a decrease in blood thyroid hormone concentrations by displacing them from binding proteins. This study investigated the effect of pergolide on the equine thyroid function. Methods: This was an analytic, observational, cohort study. Six horses (17 to 24 years old and 530 to 599 kg) received 1 mg of pergolide mesylate orally once a day from days 1 to 6. Total T4 (tT4) was measured daily from day 0 to 11 (before, during, and after pergolide treatment). Thyrotropin-releasing hormone...
Brys M, Den Hondt S, Saey V, Claerebout E, Chiers K.Various draft horse breeds, especially breeds with abundant feathering on the lower limbs, are known to be susceptible to chorioptic mange. Clinical signs of chorioptic mange encompass intense pruritus leading to self-mutilation and hair loss, thickening of the epidermis, and the formation of hyperkeratotic crusts and scabs. Despite the frequent occurrence and high impact of this condition, treatment options are limited, with a conspicuous absence of registered products formulated for equines, and especially foals. This limited availability of approved products highlights the necessity for alt...
Wong AM, Schier MF, Hosgood G, Drynan E, Raisis AL.To explore the influence of acepromazine on the cardiovascular effects of dobutamine in isoflurane-anaesthetised horses premedicated with romifidine. Methods: Prospective randomised clinical trial. Methods: A total of 18 horses undergoing elective arthroscopy were enrolled, of which 12 horses requiring dobutamine were included. Methods: Horses were randomised to receive acepromazine 0.02 mg kg (Group A+) intravenously (IV) or none (Group A-), 35 minutes before anaesthesia. Horses received xylazine 0.2 mg kg concurrently to facilitate IV access. Horses were premedicated with romifidine 0.08 mg ...
Wong JKY, Choi TLS, Wong COL, Curl P, Wan TSM, Ho ENM.Methylsulfonylmethane (MSM), also known as dimethyl sulfone, is a naturally occurring sulphur-containing compound that can be found in plants, animals and humans. MSM can also be a metabolite of dimethyl sulfoxide (DMSO). Due to their anti-inflammatory and analgesic effects, both MSM and DMSO are prohibited substances in horseracing. As both substances are naturally occurring, their misuse in horses is controlled by International Residue Limits (IRL) of 1200 and 15 μg/mL, respectively, in horse urine as established by the International Federation of Horseracing Authorities. The elimination ...
Lambertini C, Boanini E, Casalini I, Spaccini F, Rinnovati R, Romagnoli N.The aim of this retrospective clinical study was to compare the combinations of ketamine/diazepam (KD group) and tiletamine/zolazepam (TZ group) for the induction of general anaesthesia in horses undergoing elective surgery. The data from the clinical and the anaesthetic records of 138 horses from 2021 to 2023 were evaluated, and the horses were divided in two groups: KD ( = 60) and TZ ( = 72). The horses were premedicated with romifidine and methadone IV; anaesthesia was induced with ketamine/diazepam for the KD group and tiletamine/zolazepam for the TZ group and was maintained with isofluran...
Shroff K, Stefanovski D, Reef VB, Kraus MS, Solis CN.Information about congestive heart failure (CHF) treatment in the horse is limited. Torsemide, an oral loop diuretic, is increasingly used in humans, dogs, and cats with CHF. Torsemide is well absorbed and induces diuresis in healthy horses, and its use in a horse with CHF has been reported. This retrospective descriptive study aimed to describe the use of torsemide in equids with CHF. Methods: 12 equids (10 horses, 1 miniature donkey, and 1 mule). Methods: Horses presented to a referral practice with clinical signs of congestive heart failure. Diagnosis was confirmed with echocardiography. Tr...
Shinn LT, Wagner CB, Desai R, Marini BL.Horse antithymocyte globulin carries a black box warning for life-threatening anaphylactic reactions, and prescribing information recommends test doses to identify patients at highest risk of this adverse effect. The predictive value of such test doses is not well validated, and practicality of use is unclear. Methods: This was a planned secondary analysis of a multicenter, retrospective cohort study in adults with severe aplastic anemia being managed with horse antithymocyte globulin as part of their treatment regimen. Qualitative and quantitative descriptions of test doses and infusion react...
Whitaker B, Barnhard JA, Webb KR, Levine D, Green MM, Vieira MR.This study assessed the safety and tolerability of concurrent intra-articular (IA) injection of 2.5% polyacrylamide hydrogel (2.5% iPAAG) and betamethasone sodium phosphate and betamethasone acetate esters (BME) in the metacarpophalangeal joints (MCPJs) of healthy horses. Methods: 10 healthy therapeutic riding horses were enrolled in this open-label safety study from August 1 to September 14, 2023. Inclusion criteria required normal physical examinations, insulin level, hematology, biochemistry, soundness at all gaits, and negative forelimb flexion tests. Screening occurred from days -14 to -0...
Henderson ARP, Valverde A, Marchiori J, Tisotti T, Torrent A, Côté N, Gomez DE.To determine the effects of rapid (1 minute) and slow (10 minutes) intravenous (IV) injection of sodium penicillin on arterial blood pressure in anesthetized horses. Methods: Prospective randomized clinical trial. Methods: A group of 29 client-owned horses of various breeds, 1-20 years old, with body masses of 360-710 kg. Methods: General anesthesia was induced with a variety of anesthetic protocols and maintained with isoflurane under mechanical ventilation, with hourly doses of IV lidocaine and an infusion of dexmedetomidine. Horses were administered IV intraoperative penicillin every 2 hour...
Delvescovo B, Chevalier JM, Campoy L, Cercone M.To describe a technique for ultrasound-guided celiac plexus block in horses and characterize its effect on intestinal motility in healthy horses. Methods: This study was conducted from January 2022 through June 2022. In phase 1 (dye study), an ultrasound-guided technique was optimized, and dye deposition around the celiac plexus branches was evaluated via postmortem dissection in 6 horses. In phase 2 (experimental study), 6 healthy horses were fasted and sedated with 0.6 mg/kg xylazine, IV (experiment 1). After a washout period, the ultrasound-guided celiac plexus block with lidocaine 1% (1.3 ...
Larson MA, Credille BC, Berghaus LJ, Papich MG, Beasley EM.To investigate the disposition of enrofloxacin and its active metabolite, ciprofloxacin, in plasma, pulmonary epithelial lining fluid (PELF), peritoneal fluid, and CSF in horses following IV administration of enrofloxacin at doses of 5 mg/kg and 7.5 mg/kg of body weight. Unassigned: 6 healthy, mature mares were randomly assigned to receive a single dose of enrofloxacin at either 5 mg/kg or 7.5 mg/kg in a crossover design with a washout period of 10 days. Concentrations of enrofloxacin and ciprofloxacin were determined in plasma, PELF, peritoneal fluid, and CSF. Unassigned: Both doses of enrofl...
Harding C, Viljanto M, Hincks P, Habershon-Butcher J, Paine SW.Omeprazole is a gastric acid secretion inhibitor used as an effective anti-ulcer drug. Based on oral administration studies, its International Screening Limit (ISL) was established in plasma and urine at 1 ng/mL with a Detection Time (DT) of 48 h. A novel formulation of injectable omeprazole has since been released, and therefore, a pharmacokinetic study was performed to assess the DT above the ISL against current advice. Six Thoroughbred horses were given four repeated weekly intramuscular administrations of omeprazole (4 mg/kg). Plasma and urine omeprazole concentrations were measured ...
Hardefeldt LY, Thomas K, Begg L.Antimicrobial resistance (AMR) is a problem for equine practitioners in Australia, but antimicrobial use in practice has been largely understudied. We aimed to evaluate equine veterinarians' intentions of prescribing antimicrobials in areas where we perceived there to be wide ranges of practice - dentistry, reproduction and for nonbactericidal effects. Methods: An online cross-sectional survey of veterinarians working in equine practice was conducted over 4 months in 2023 and 2024. Antimicrobial use, including compounding practices, for reproductive and dental disorders, and nonbactericidal...
Entwisle IG, McConnell EJ.Sand enteropathy describes the clinical signs attributed to accumulation of sand in the gastrointestinal tract. Psyllium combined with magnesium sulphate has been recommended for clearing intestinal sand, but this has only been evaluated in one population. The combination of these two agents with paraffin oil has not been investigated. Objective: To investigate the effectiveness of paraffin oil, psyllium and magnesium sulphate combined in clearing intestinal sand in horses diagnosed with sand enteropathy. Methods: Retrospective case series. Methods: Medical records of horses presenting for san...
Hordle T, Ranninger E, Bettschart-Wolfensberger R.A 24 year old warmblood mare (case 1) and a 12 year old Holsteiner gelding (case 2) were anaesthetized for bursoscopy and phacoemulsification, respectively. Both were premedicated with intramuscular acepromazine (30 μg kg-1). The horses were sedated with intravenous (IV) medetomidine (7-9 μg kg-1 to effect), before anaesthetic induction with ketamine-diazepam. Anaesthesia was maintained with isoflurane in a mixture of oxygen and medical air, alongside a medetomidine constant rate infusion at 3.5 μg kg-1 hour-1. In recovery, 3 and 5 μg kg-1 of medetomidine were administered IV to cases 1 an...
Kintz P, Baudry M, Gheddar L.Trazodone, a medicine registered for human, is a serotonin agonist-antagonist. At low dose, the drug is sedative due to its antagonist properties. At high dose, it is an agonist with anxiolytic and antidepressant actions. Trazodone can be administered to the horse to reduce anxiety. However, according to the anti-doping rules for horses, the presence of trazodone in blood or urine is considered as a violation which will produce a suspension of both the athlete and the horse as the drug is listed banned on the International Federation of Horseracing Authorities prohibited substances list. As a ...
Roccaro M, Rinnovati R, Stucchi L, La Rocca F, Cascio G, Peli A.Doping in racehorses is a threat to horse welfare and the integrity of the sport. Despite its relevance, the literature on the prevalence of anti-doping violations worldwide is limited. Objective: To analyse anti-doping violations in racehorses in Italy. Methods: Retrospective observational study. Methods: Data on horse races, anti-doping testing, and confirmed violations between 2014 and 2022 were collected and analysed. Positivity rates, most common drug classes and parent drugs, and differences between trotting and galloping horses were investigated. Results: During the considered 9-year ti...
Ho HSM, Farrington AF, Ho ENM, Wong WT.2-Hydroxyethyl salicylate (2HES), a nonsteroidal anti-inflammatory drug (NSAID), is a medication to treat musculoskeletal injuries and inflammation swelling of humans and horses. Its misuse could affect the performance of horses and mask injuries, which could pose significant health risks. In horseracing, it is reported as an adverse finding once detected in competition. The metabolism of 2HES in either human or horse has not been reported, and therefore, little is known about its metabolic fate. This paper describes the in vivo metabolism of 2HES in horse with an objective to identify the mo...
Munerato MS, Simon O, Nicholson A.This report describes successful cardiopulmonary resuscitation of a healthy, 525 kg, 8 years 9 months-old Quarter horse gelding. After successful pelvic limb orthopaedic surgery to excise a metatarsal bone under general anaesthesia, with the horse in left lateral recumbency, the horse was hoisted into recovery. After the horse was positioned in recovery, a routine cardiac check by thoracic auscultation was performed. Cardiopulmonary arrest (CPA) was identified by absence of cardiac sounds and pulse, as evaluated by digital palpation of the facial artery, absence of the right palpebral reflex, ...
Labens R, Saba C, Williams J, Hollis A, Ensink J, José-Cunilleras ELV, Jordana-Garcia M, Bergvall K, Ruppin M, Condon F, Spelta C, Elce Y....Intralesional chemotherapeutic administration represents an important treatment option for equine cutaneous neoplasia. Tigilanol-tiglate (TT), a novel molecule extracted from Fontainea picrosperma, an Australian rainforest plant, is registered for intratumoural treatment of canine MCT, leading to rapid oncosis and tumour slough. Evidence from horses is limited but suggests that efficacy may be similar. Objective: To evaluate the response to intratumoural TT treatment in horses with sarcoids (fibroblastic/nodular) and cutaneous melanomas. Methods: Two noncontrolled prospective multicentre clini...
Karačonji IB, Jelača T, Jurič A, Vrdoljak AL.Opiates such as morphine and codeine are substances often misused to improve the performance of racing horses during competitions and are therefore on the International Federation for Equestrian Sports' list of prohibited substances. However, a positive antidoping test may be due to the consumption of feed (mainly lucerne or oats) contaminated by opium poppy containing the alkaloids morphine and codeine. In order to determine whether a positive antidoping test is the result of an intentional abuse of opiates or consumption of feed contaminated by poppies, we optimised conditions for the extrac...
Quattrini C, Knych HK, Magdesian KG.Alprazolam is used to facilitate mare-foal bonding in aggressive or anxious postpartum mares. In humans, alprazolam crosses the blood-milk barrier, but the amount transferred into milk is minor and compatible with breastfeeding as the relative infant dose is < 10%. Similar data are not available for horses. The aim of this study was to measure alprazolam in serum and milk of mares (milk: serum ratio) administered alprazolam, and to determine alprazolam serum concentrations in nursing foals to estimate the extent of absorption. This was a prospective observational study involving 7 healthy...
Kinoshita Y, Niwa H, Ueno T.In horses, the gut microbiota plays a critical role in maintaining intestinal homeostasis and overall health, but antimicrobial administration can disrupt its balance, resulting in dysbiosis, which can cause antibiotic-associated diarrhea. This study assessed the impact of intravenous cephalothin sodium administration on the equine gut microbiota by using microbial amplicon sequencing targeting the 16S-ITS-23S rRNA operon. Fecal samples from 39 clinically normal horses, 16 antibiotic-treated horses (cephalothin, n=5; minocycline, n=5; metronidazole, n=6, each administered for 5 days), and seve...
Chambers A.All anti-doping programmes face financial constraints and monitoring trends in medication use or abuse in a population of racehorses can be difficult and expensive. Obtaining biological samples is the primary method of anti-doping control in individual horses or stables of horses but can be invasive and expensive. Another important practice of anti-doping control has been the confiscation of used and filled syringes by regulators for individual forensic analysis. Pooled samples testing involves the testing of multiple individual samples together as one composite sample. This pooled sample appr...
Bardhi A, Lanci A, Mannini A, Castagnetti C, Barbarossa A.Background: Although antibiotic resistance is a well-known issue in veterinary medicine, studies proposing real-time therapeutic monitoring (TDM) are lacking. The objective of the present study was to develop a simple and rapid protocol for the real-time therapeutic monitoring of antibiotics in horses and dogs. Methods: A reliable TDM protocol should encompass guidelines for the definition of plasma/serum collection time points, sample management by the clinical staff, transportation to the laboratory, and the availability of robust and swift analytical technologies. Ampicillin and sulbactam w...
Schott HC, Strachota JR, Marteniuk JV, Refsal KR.Limited data document long-term responses of equids with pituitary pars intermedia dysfunction (PPID) to pergolide treatment. Objective: Report clinical response, medical problems, outcome, and owner satisfaction with pergolide treatment of PPID-affected equids over 14 years. Methods: Thirty client-owned equids with PPID. Methods: After completion of an open field clinical efficacy study for Prascend® (pergolide tablets), 28 horses and two ponies were enrolled in an extended treatment study (13 receiving 2 μg/kg PO q24h and 17 receiving 4 μg/kg PO q24h). Clients were interviewed eve...
Ho HSM, Mizzi JX, Ho ENM, Wong WT.Ranitidine is a histamine H-receptor antagonist commonly used to treat gastric ulceration in horses. The author's laboratory conducted a study some years ago in the early 2000s on its metabolism as well as its urinary elimination profile in two geldings. With the technology advancement as well as popularity of blood for doping control testing, the laboratory has recently conducted another administration trials of the substance in six horses to study the in vivo metabolism of ranitidine, aiming to identify and reinvestigate the appropriate target(s) for controlling misuse of ranitidine in hors...
Stuart RB, Miles-Farrier F, Bard AM, Rees G.Antimicrobial resistance (AMR) is an increasingly serious threat to human and animal health. Antimicrobial use (AMU) in horses is gathering research interest, although there remain significant evidence gaps. Currently, there is scant qualitative research into equine owners' use of antimicrobials, specifically antibiotics, hindering the design of evidence-based stewardship interventions and policies. Objective: To understand Welsh equine owners' views and behaviours relating to antimicrobial usage. Methods: Cross sectional survey and qualitative data collection and analysis. Methods: An online ...
El-Ghaly W, El Kamli T, Gongbe AMA, Zaari Lambarki L, El Hamdani M, Lahkak FE, Al Idrissi N, Benmoussa A, Balouch L, Bakkali F, Saffaj T, Jhilal F.The quantification of banned substances in equine antidoping control, especially in racehorse urine, necessitates robust analytical methods with high detection levels due to the extremely low concentrations of the target substances and the significant impact of minor variations on doping test results. Reliable quantification is important for substances near regulatory thresholds, which, if exceeded, are prohibited. This study presents the development and validation of a bioanalytical UHPLC-HRMS method for quantifying doping substances in equine urine, including diazepam and acepromazine with a...
Bardhi A, Barbarossa A, Joubert A, Gehring R, Lambertini C, Romagnoli N.Dried blood spot (DBS) sampling has emerged as a promising microsampling technique in biomedical and clinical research, offering advantages such as reduced invasiveness, minimal blood volume requirements, and enhanced analyte stability. Although well established in human medicine for neonatal screening and diagnostic applications, its potential in veterinary pharmacology remains underexplored. This study investigated the feasibility of using DBS samples to quantify anesthetic agents-ketamine and medetomidine in cats and lidocaine in horses-during routine surgical procedures at a veterinary tea...
