Pharmacology in horses involves the study and application of drugs and medications to diagnose, treat, and prevent diseases and conditions in equine species. This field encompasses the understanding of pharmacokinetics and pharmacodynamics specific to horses, including how drugs are absorbed, distributed, metabolized, and excreted by the equine body. Commonly studied pharmacological agents in horses include non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, sedatives, and anthelmintics. Research in equine pharmacology focuses on determining appropriate dosages, understanding drug interactions, and minimizing adverse effects. This page compiles peer-reviewed research studies and scholarly articles that investigate the efficacy, safety, and regulatory aspects of pharmacological interventions in equine veterinary practice.
Munsterman AS, Dias Moreira AS, Kottwitz J.To evaluate the effects of detomidine on equine intestinal slow-wave activity and frequency distribution measured by electrointestinography (EIG). Methods: Prospective, experimental study. Methods: University teaching hospital. Methods: A convenience sample of twelve 7- to 21-year-old clinically normal horses. Methods: Horses were randomly assigned to saline control (four horses) or detomidine treatment (eight). After obtaining a 30-min baseline EIG, a saline or detomidine bolus was administered, followed by a constant rate infusion, and another EIG was recorded. Ultrasonographic examinations ...
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...
Hallman IAM, Raekallio MR, Karikoski NP.Vatinoxan is a peripherally acting alpha2-adrenoceptor antagonist used in veterinary medicine to attenuate the side effects of alpha2-adrenoceptor agonists. Vatinoxan also increases insulin response and reduces blood glucose (BG) after intravenous glucose in other species. The aim of this study was to investigate the effects of vatinoxan on BG and insulin concentration in horses after intravenous glucose. The design was an assessor-blind cross-over study. Nine horses were assigned to intravenous vatinoxan (0.2 mg/kg; VAT) or saline (SAL). Horses were administered an intravenous glucose bolus (...
Buzelato Carli I, Fielding L.Many horses receive firocoxib over multiple years, and studies evaluating hematologic and biochemical values in these animals are lacking. Objective: To describe the hematologic and biochemical values of horses receiving long-term firocoxib. Methods: A total of 79 horses receiving long-term firocoxib and 153 horses not receiving long-term firocoxib and not presenting for a specific medical problem. Methods: Retrospective study comparing horses receiving firocoxib (F group) and no firocoxib (NF group). Signalment, hematologic, and biochemical values were compared between the two groups. Simple ...
Cardinaux EM, Oltmanns H, Beineke A, Meißner J, Geburek F.Flexural limb deformities are a widespread condition in foals. Oxytetracycline is a common conservative treatment option with relaxing effects on the muscle-tendon-unit, potentially mediated through a matrix-metalloproteinase (MMP)-inhibitor mechanism. Its high therapeutic dose for this indication, potential negative side effects, and the guidelines for prudent use of antimicrobials make investigating alternatives desirable. In this study, the influence of substances with potentially similar mechanisms of action, however without antimicrobial properties, on viability and proliferation of juven...
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...
Bianchi D, Santos RRD, Peleja PL, de Sousa ABB, da Silva Evangelista M, de Almeida Júnior JS, Barata LES, Moraes WP, Minervino AHH. (tropical horse tick) is a tick species commonly found parasitizing horses and other equids in the Amazon region, causing economic losses. Currently, tick control is based on chemical acaricides, usually in a power formulation for topical use. However, its indiscriminate use results in the emergence of resistant tick lineages. Several plant compounds have been tested for their acaricide activity. In the Amazon, several plants are used for oil extraction, resulting in the production of solid residue (waste) that may contain chemical molecules with biological activities. Thus, we aimed to test ...
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...
Bazzano M, Laus F, Cerquetella M, Spaterna A, Marchegiani A.Phytocannabinoids have the potential to lower intraocular pressure in both normal and glaucomatous eyes and they have been tested in different animal species, but not in the horse. The present paper describes the tonometric curve of healthy adult Italian Saddle horses after oral administration of cannabidiol oil (CBD). Methods: CBD 20% was administered orally (oily solution) at the dose of 1 mg/kg to 8 adult horses and intraocular pressure (IOP) was evaluated by tonometric curve. Data were then compared to those of the same horses obtained the day before (blank) CBD administration. Results: ...
Sobhy A, Nomir AG, Hamed MA, Abumandour MMA, El-Kammar M.The current study was prepared to compare the efficacy of xylazine-lidocaine HCl and detomidine-lidocaine HCl following caudal epidural injection in horses, evaluating sedation, analgesia, physiological parameters, and hemato-biochemical values. This study was applied to six healthy adult horses (300-350 kg, > 4 years of age). The horses were randomly divided into two equal groups. Group 1 (seven horses) received xylazine (0.17 mg/kg bwt) + lidocaine HCl (0.06 mg/kg bwt), while Group 2 received detomidine (0.03 mg/kg bwt) + lidocaine HCl (0.06 mg/kg bwt) via caudal epidural inje...
Tarillion M, Hertzsch R, Richter A.Since 28.01.2022, veterinary medicinal products must be used in accordance with the conditions of authorization (Regulation (EU) 2019/6, Article 106). This entails further restrictions on therapeutic freedom, e. g., with regard to dose deviations. To date, there is no data available in equine medicine on the scope of off-label use as any use deviating from the expert information for antibiotics, on the basis of which the feasibility of implementing the new regulations in Germany can be assessed.To collect data on the off-label use of antibiotics, a Germany-wide anonymous online survey was th...
Bacon EK, Finno CJ, Donnelly CG, Haase B, Knych HK, Velie BD.Clinical assessments of equine sedation typically rely on subjective observations, the accuracy of which is paramount to the safety of equine veterinary procedures. Methods: To assess the degree in which subjective clinical sedative evaluations reflect pharmacokinetic measurements of equine drug metabolism, xylazine hydrochloride, an alpha-2 adrenoreceptor agonist, was administered to 36 horses of varying breed and age at a dosage of 0.5 mg/kg body weight. Subjective clinical parameters were scored at 5-, 15-, 30-, 45- and 60-minutes post xylazine administration and included responsiveness to ...
Blanton A, Glass KG, Bayer J, Baetge C, Watanabe R, Sampson SN, Lépiz M, Moreno K, Ida KK.Pregabalin reduces excitatory neurotransmitter release and is used for anxiolysis in humans, cats, and horses. The effects of pregabalin on equine recovery following isoflurane anaesthesia are unknown. Objective: To determine if pre-anaesthetic oral pregabalin influences recovery time and/or quality from isoflurane anaesthesia in horses undergoing elective magnetic resonance imaging (MRI) of the appendicular skeleton. Methods: Retrospective cohort study. Methods: Anaesthetic and recovery data from 52 healthy horses in which pregabalin (PG) was administered and 76 control horses (CG) undergoing...
Mountessou BYG, Mouafon IL, Maharjan R, Tchamgoue J, Tiani GLM, Dibouloul P, Choudhary MI, Kouam SF.Four previously undescribed phenazine-derived pigments (1-4), along with seventeen known compounds, were isolated from a strain cultured on solid rice medium. Structural elucidation of the new compounds was achieved through extensive spectroscopic analysis, while known compounds were identified by comparison with literature data. The antimicrobial and cytotoxic activities of the isolated compounds were assessed. Compounds 2, 5, and 11 exhibited weak antifungal activity against at 200 μM, while compounds 5, 6, 11, 12, 15, and 20 demonstrated moderate antibacterial effects against at the sam...
Morales CJ, Sykes BW, McKemie DS, Kass PH, Knych HK.Current treatment options for equine gastric ulcer syndrome (EGUS), such as omeprazole-a proton pump inhibitor (PPI)-have notable limitations, including the need for administration on an empty stomach. Potassium-competitive acid blockers (P-CABs), such as vonoprazan, are a newer class of acid suppressants that offer several advantages over PPIs in humans and may provide similar benefits in horses. Objective: To describe the pharmacokinetics and effect of a single oral dose of vonoprazan on intragastric pH in horses. We hypothesised that vonoprazan would follow linear kinetics across the doses ...
Macias A, Delvescovo B, Donaldson SF, Divers TJ, Donnelly CG.Ursodeoxycholic acid (UDCA), a secondary bile acid (BA) with therapeutic applications, is standard therapy for cholestatic hepatopathies in humans. In recent years, its use has been increasingly explored in equine medicine for similar indications. Pharmacokinetic data for UDCA in horses are currently lacking. This study aimed to describe the pharmacokinetic parameters following a single intragastric administration of 15 mg/kg in nine healthy, fasted horses and to characterize the changes in their BA profiles. Plasma concentrations of UDCA were measured at specific time points using liquid ch...
Honkavaara JM, Karikoski NP, Palvas L, Pypendop BH, Rinne VM, Raekallio MR.The aim of the study was to determine the exposure to subcutaneously administered butorphanol in horses pre-treated with intravenous (IV) detomidine, with or without vatinoxan, a peripherally selective alpha-adrenoceptor antagonist. Five healthy, adult horses received three IV treatments 7 days apart, in a randomized, cross-over design: detomidine 20 μg/kg (DET-B), detomidine 20 μg/kg with vatinoxan 200 μg/kg (DETVAT-B) and saline (S-B), all followed by 0.1 mg/kg of butorphanol administered subcutaneously 30 min later. Venous samples were collected between 10 and 270 min after...
Rollet M, Flyps J, Vernemmen I, van Loon G, Schauvliege S.Hyperkalaemia is an uncommon complication of general anaesthesia in healthy horses. This case report describes the occurrence of life-threatening acute hyperkalaemia in a 13-year-old, female French Trotter anaesthetised for experimental right and left atrial 3D electro-anatomical mapping. Intra-operative development of hyperkalaemia (7.55 mmol/L) (Ref. 3.00-4.00 mmol/L) with atrial standstill on ECG necessitated transvenous ventricular pacing while initial treatment with insulin and glucose was initiated. Plasma potassium levels continued to increase (8.00 mmol/L) prompting adjunctive tr...
Faugier C, Snyder LBC, Hyun M, Schroeder C.To evaluate sedation in horses following pharmacopuncture with dexmedetomidine at acupoint Governing Vessel 24 (GV-24) compared to aquapuncture at GV-24 or an equivalent dose of dexmedetomidine administered via IV or SC routes. Unassigned: 10 adult mares received 4 treatments in a blinded, randomized, crossover design: (1) dexmedetomidine administered at GV-24 (DexmedGV24; 1 μg/kg); (2) saline administered at GV-24 (SalineGV24; 1.5 mL); (3) dexmedetomidine administered SC on the lateral neck (DexmedSC; 1 μg/kg); or (4) dexmedetomidine administered IV (DexmedIV; 1 μg/kg). Sedation scores (fa...
Whitelock A, Goodwin W, Dryburgh L, Mshelbwala PP, Rae L, Marwedel L, Lok T, Kemp K, Stewart AJ.To describe Australian practices and attitudes regarding equine analgesia. Methods: Cross-sectional anonymous, voluntary survey of Australian veterinarians treating equine patients. Methods: Australian veterinarians in equine or mixed practices completed a six-section, 60-question survey between November 2019 to August 2020. Information was gathered on demographics, analgesia prescription, pain assessment and attitudes surrounding specific analgesics. Respondents assigned a pain score ranging from 0 to 10 for various conditions; these were averaged to give each respondent an "average pain scor...
Jung Y, Yoon M.Oxytocin (OXT) plays a crucial role in regulating the serotonin (5-HT) system and behavior. Although previous studies have reported significant relationships among OXT, 5-HT, and behavioral responses, the effects of OXT on 5-HT concentrations and behavioral traits in horses remain poorly understood. This study aimed to investigate the effects of intravenous OXT administration on plasma 5-HT concentrations and trainability in horses. A crossover design was employed using eight horses, each receiving either a 10-IU intravenous dose of OXT or normal saline. Blood samples were collected at baselin...
Auvinen JRE, Kritchevsky JE, Reinhart JM, Gochenauer AE, Jannasch AS, Han-Hallett Y.Manipulation of forms of rectally administered metronidazole to improve bioavailability in horses has not been reported. Objective: Evaluate the pharmacokinetics of 3 rectal metronidazole preparations compared to nasogastric (NG) administration. Methods: Seven healthy horses. Methods: Phase 1A was a randomized, 3-way crossover, single-dose pharmacokinetic study, and Phases 1B and 2 were non-randomized, single-dose follow-up studies. Metronidazole (20 mg/kg) was administered NG and rectally in water (RW20), as a rectal gel (RG), and in dimethyl sulfoxide (DMSO). Metronidazole (80 mg/kg) was a...
Semik-Gurgul E, Ocłoń E, Zubel-Łojek J, Pędziwiatr R, Pawlina-Tyszko K.Sarcoids are locally invasive skin tumors in equids, associated with bovine papillomavirus. Objective: Address potential applications of cannabidiol (CBD) in veterinary medicine. We evaluated the response of equine sarcoid cells to CBD in vitro, focusing on viability, invasiveness, and matrix remodeling. Methods: Three primary sarcoid cell lines. Methods: Cells were treated with CBD (20, 6.75, 2.25, 0.75 μM) and incubated for 6, 24, 48, 72 hours. Cell viability, cytotoxicity, and apoptosis were assessed using the ApoTox-Glo Assay. Based on these results, further analyses were performed for ...
Gray B, Lubbock K, Love C, Ryder E, Hudson S, Scarth J.The analytical approaches taken by laboratories to implement robust and efficient regulation of horseracing medication and doping control are complex and constantly evolving. Each laboratory's approach will be dictated by differences in regulatory, economic and scientific drivers specific to their local environment. However, in general, laboratories will all be undertaking developments and improvements to their screening strategies in order to meet new and emerging threats as well as provide improved service to their customers. In this paper, the published analytical advances in horseracing me...
Mazzuchini MP, Lisboa FP, Segabinazzi LG, Canisso IF.Endometritis is the leading cause of mare subfertility. Most mares respond to standard therapy, but alternative therapies have been developed for mares failing to respond. This study aimed to investigate a commercially available, yet unassessed, product labeled as a uterine sanitizer to determine the in vitro antimicrobial activity against microorganisms associated with endometritis and its in vitro stability to dilute antibiotics. In experiment 1, the microdilution broth technique and antimicrobial effects were assessed against Escherichia sp, Staphylococcus sp., Klebsiella sp., Pseudomonas s...
Raidal SL, van Diggelen M, Catanchin CSM, Lehmann HS, Quinn CT.Noninvasive ventilation (NIV) provides effective respiratory support in foals, but face masks are poorly tolerated and associated with hypercapnia. Bi-nasal prongs might be a more effective device interface in foals. Objective: To compare bi-nasal prongs and masks for NIV in foals with pharmacologically induced respiratory insufficiency. Methods: Six healthy foals. Methods: In a randomized cross-over study, sedated foals received NIV delivered by mask or bi-nasal prongs, with the treatment repeated using the alternative device interface after a 3-day rest period. After periods of spontaneous v...
Bertin FR, van Eps AW, de Tonnerre DJ, Kulp JC, Stefanovski D.Dexamethasone is used to experimentally induce insulin resistance; however, its impact on insulin secretion is unclear. This study aimed to assess the responses to oral carbohydrate challenges in dexamethasone-treated horses. Unassigned: 8 healthy Standardbreds received 0.08 mg/kg of dexamethasone IM every 48 hours for 14 days in June 2022 (winter in the Southern hemisphere). Oral glucose tests (OGT) were conducted before treatment (day 1) and on days 8 and 15. Glucose, insulin, triglycerides, total and active glucagon-like peptide-1 (tGLP-1 and aGLP-1) and glucose-dependent insulinotropic pol...
Carroll AT, Reed RA, Berghaus LJ, McNabney D, Knych HK.To investigate the effect of cannabidiol (CBD) on thermal and mechanical thresholds and physiologic variables in horses. Unassigned: 6 horses (3 geldings and 3 mares) were enrolled in a prospective, randomized, masked crossover design from March 18 through May 3, 2025. Horses received 3.48 mg/kg CBD oil or placebo (sesame oil) orally every 24 hours for 3 days. Thermal and mechanical thresholds were determined at baseline and 4 and 12 hours after treatment administration on each day. Physiologic variables, including heart rate, respiratory rate, and rectal temperature, were recorded at the same...
Menzies-Gow NJ.Pituitary pars intermedia dysfunction (PPID) is a common, slowly progressive, neurodegenerative disorder of the older horse. Oxidative damage to the hypothalamic periventricular neurons results in loss of dopaminergic inhibition of the pars intermedia region of the pituitary gland. Consequently, there is increased production of the pro-opiomelanocortin (POMC)-derived hormones normally produced by this region, as well as initial melanocyte hypertrophy and hyperplasia, followed by adenomatous change. Clinical signs that are highly suggestive of the disease are generalised and regional hypertrich...
Darby S, DeNotta S, Gomez DE.This report describes a case of ivermectin toxicosis in a 4-day-old thoroughbred colt successfully treated with intravenous lipid emulsion (ILE) without complications. This case supports the use of ILE as a safe and effective therapy for the management of lipophilic drug toxicosis in foals. Key clinical message: Ivermectin toxicosis, though rare in equine neonates, can occur following accidental overdose and induces severe neurologic signs. In this case, ILE administration resulted in rapid neurologic improvement and complete recovery without adverse effects, supporting its use as a safe and e...
