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Topic:Adverse Effects
Adverse effects in horses refer to unintended and potentially harmful outcomes that occur as a result of medical treatment, environmental exposure, or other interventions. These effects can impact various physiological systems and may manifest as behavioral changes, organ dysfunction, or other health-related issues. Monitoring and understanding adverse effects are important for ensuring the safety and well-being of horses, particularly in the context of veterinary medicine and equine management. This page gathers peer-reviewed research studies and scholarly articles that explore the causes, mechanisms, and implications of adverse effects in horses, offering insights into their identification, management, and prevention.
Seizures and blindness onset zone in 7 horses undergoing radiographic myelography in lateral recumbency under inhalation anesthesia. Seizures and blindness are potential complications associated with myelography. Objective: Describe, classify, and determine onset zone of seizures and blindness in horses undergoing radiographic myelography in lateral recumbency. Methods: Seven young adult horses. Methods: Retrospective study. Horses with seizures or blindness associated with myelography were included. Results: Three horses with general proprioceptive ataxia and 4 neurologically normal horses (Warmblood = 4, Thoroughbred = 3), ages 9 (range, 3-16) years old. Iohexol (300 mg I/mL) from 50 to 60 mL (0.09-0.1 mL/kg) were ...
Analgesic use, safety and pharmacokinetics of acetaminophen in equids: A structured scoping review. Despite its frequent use in equine clinical practice, scientific data on the use of acetaminophen in horses remain limited. Objective: To map and critically appraise the available evidence on the analgesic use, safety and pharmacokinetics of acetaminophen in horses. Methods: Structured scoping review. Methods: A comprehensive search was performed in accordance with the PRISMA Extension for Scoping Reviews using the terms '(paracetamol OR acetaminophen) AND (pain OR safety OR toxicosis OR pharmacokinetics) AND (horse OR pony OR donkey OR mule)' across Web of Science, Scopus, and PubMed from dat...
Complications Following Nictitating Membrane Resection in Horses: 92 Eyes (2015-2024). The goal of this retrospective study is to evaluate the complications following nictitating membrane resection in horses with the aim of providing valuable information on the risks of this surgical procedure. Methods: 83 horses (92 eyes). Methods: Medical records for 83 horses that underwent nictitating membrane resection in 92 eyes between February 2015 and June 2024 were reviewed. Horses were included if they had at least 1 month of follow-up data available. Owners were contacted via telephone or email questionnaire to obtain follow-up information. Complications were recorded only when pre...
Intratumoral para-toluenesulfonamide as a tumor-ablative therapy for equine cutaneous tumors: a case series of three horses. Equine neoplasia, including sarcoids, melanomas, and squamous cell carcinomas, presents therapeutic challenges due to recurrence and limitations of conventional treatments. Para-toluenesulfonamide (p-TLS) is a tumor-ablating agent that is associated with localized tumor necrosis and subsequent lesion resolution. It has been evaluated in human clinical settings as an intratumoral treatment of malignant airway obstruction caused by non-small cell lung cancer. This study aimed to describe the clinical outcomes and tolerability of intratumoral p-TLS in equine neoplasia. Three equine cases, includi...
Canagliflozin treatment of a horse with hyperinsulinemia, including pharmacokinetic analysis of different dosing protocols: a case report. Laminitis is a complex and painful disease of the equine foot. Insulin dysregulation (ID) resulting in hyperinsulinemia is responsible for more than 90% of cases in the general horse and pony population. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a relatively new class of drug that has gained considerable popularity as an off-label treatment of hyperinsulinemia-associated laminitis (HAL) in horses when traditional management changes and treatments are unsuccessful. In Canada, canagliflozin is the SGLT2i most available to equine veterinarians; although no dosing protocols have been ...
Using a wearable electrocardiogram (ECG) patch adapted for 7-day monitoring in the horse. Arrhythmias can cause poor performance and sudden death in horses. Long-term (>24 h) electrocardiogram (ECG) monitoring has been used to identify arrhythmias in humans and is superior to short-term monitoring for transient arrhythmia detection. Televet is the current equine gold-standard ECG device. The Cardea SOLO™ (CS) is a single-use monitor with automated ECG analysis software allowing ECG monitoring for 7 days. Objective: Our objective was to validate the performance of the CS compared to the Televet. Methods: Method validation. Methods: ECGs were performed on 12 healthy horses s...
Efficacy and safety of canagliflozin in insulin dysregulated horses: a 4-week multi-arm, double-blind, randomized, clinical trial. Sodium-glucose cotransporter-2 (SGLT2) inhibitors are promising drugs for treatment of hyperinsulinemia in insulin-dysregulated (ID) horses. Objective: Compare short-term effects of the SGLT2 inhibitor canagliflozin versus placebo on glucose and insulin responses during an oral sugar test (OST) and a forage-based feed challenge test (FCT), and to assess adverse effects. Methods: Forty-two privately owned severely ID horses. Methods: Multi-center, randomized, double-blind, placebo-controlled, parallel-group study. Horses were allocated (1:1:1) to receive canagliflozin (0.6 or 1.2 mg/kg PO q24h...
Efficacy of 0.5% Tretinoin in the Treatment of Equine Aural Plaques. Equine aural plaques are a benign form of auricular papillomatosis caused by equine papillomavirus. Despite the efficacy of 5% imiquimod cream, a marked local reaction is frequently observed during therapy, often requiring sedation before application. Objective: The aim of this study was to evaluate the efficacy and potential adverse effects of 0.5% topical tretinoin in the treatment of equine aural plaques. We hypothesised that tretinoin would be effective, with fewer adverse effects compared to imiquimod. Methods: The study included 10 horses of both sexes, aged between 7 months and 15 y...
Treatment of ventricular arrhythmias with oral sotalol in four horses. Sustained ventricular arrhythmias (VAs) in horses can require medical intervention. Prompt pharmacological treatment is indicated when the arrhythmia leads to hemodynamic or electrical instability. Established antiarrhythmic treatment of VA in horses includes lidocaine and magnesium, administered parenterally. Other antiarrhythmic agents are used; however, concerns regarding adverse effects, financial restrictions, logistics of administration, and lack of access often limit their use. While anecdotal reports of oral administration of sotalol for treatment of VA in horses exist, sotalol has pri...
The immediate effect of whole-body vibration therapy on mechanical nociceptive thresholds in horses with thoracolumbar pain. Treating primary back pain in horses can be challenging and often necessitates a multimodal approach. Whole-body vibration therapy (WBV) has been used in both horses and humans to alleviate pain and strengthen muscles. A recent study showed worsening back pain following a 30-minute session of WBV; however, the immediate effects of WBV were not evaluated. The purpose of this study was to assess the immediate effects of whole-body vibration therapy on horses with back pain after a single session of WBV. Objective: The objective of the current study was to determine the immediate effects on mecha...
Pharmacokinetics of Intramuscularly Administered Ketamine at Subanaesthetic Dosage in Horses. Subanaesthetic doses of ketamine (0.5 mg kg) provide analgesia in several species, but there is limited information on the pharmacokinetics and clinical effects of intramuscularly administered ketamine in horses. This study investigated the pharmacokinetics of ketamine and norketamine, and evaluated clinical effects, ataxia, and vital parameters, following intramuscular and intravenous administration of 0.5 mg kg ketamine in nine healthy horses, using a randomized two-period crossover design with a 1-week washout period. Plasma concentrations were analyzed using Ultra-High Performance ...
Plasma Concentrations Following Oral Administration of Two Different Forms of Resveratrol in Horses. Resveratrol is a compound found in multiple plants and there is evidence for its use as a supplement in horses, particularly through protection of chondrocytes. Previous studies on the clinical efficacy of resveratrol supplementation in horses have reported limited benefits. To date, there is no pharmacokinetic data of resveratrol in horses but the bioavailability of resveratrol in other species is poor. In this crossover study, the plasma concentrations of two forms of resveratrol were examined. Each horse received via nasogastric tube, either a single dose of resveratrol phospholipid or a st...
Topical treatment of equine aural plaques with nitric acid and zinc solution. Equine aural plaque caused by equine papilloma viruses is common worldwide and affected horses can show severe clinical signs. Due to its viral aetiology, in some countries affected horses are not allowed to compete. Since lesions persist, showing no spontaneous regression, effective and safe treatment is required. Currently, the only treatment with consistent efficacy is imiquimod. Treatment time is prolonged and adverse effects are common. In humans, papilloma warts are successfully and safely treated with topical nitric-zinc complex solutions inducing a painless caustic effect. Objective: T...
Photodynamic therapy with infracyanine green induces keratocyte depopulation in the normal equine cornea. Use of photodynamic therapy (PDT) for the treatment of immune-mediated keratitis (IMMK) in horses is becoming common. The safety and morphologic impact on the normal equine cornea have not been investigated, and the mechanism of its efficacy is unknown. Objective: To investigate the morphologic effects and safety of in vivo PDT on healthy equine corneas. Methods: In vivo experiment. Methods: Six university-owned horses underwent unilateral corneal PDT with intrastromal infracyanine green (EmunDo®) and photoactivation with an 810 nm diode laser (500 mW for 2.5 min = 75 Joules). Compl...
Pharmacokinetics of Topical Administration of Altrenogest in Mares and Implications for Human Health. Altrenogest is a synthetic progestogen widely used in equine reproductive management. Adverse effects to altrenogest have been reported in people with cutaneous exposure reported as the highest exposure pathway. Despite these reports, there has been no quantitative research to determine the capacity for altrenogest to be absorbed through skin. This study aimed to determine if cutaneous application of oral altrenogest results in systemic absorption in mares and to evaluate the influence of application site. A randomized, two-period, two-treatment crossover study was undertaken in eight mares. M...
Reducing Recurrence in Equine Corneolimbal SCC: Outcomes of Adjunctive Cisplatin Biodegradable Bead Therapy. (1) Context: Squamous cell carcinoma (SCC) is the most prevalent ocular neoplasm in horses, with a reported 45% recurrence rate when managed by surgery alone. (2) Objective: To evaluate the effect of adjunctive cisplatin biodegradable beads (CBBs) on recurrence rates of equine corneolimbal squamous cell carcinoma (SCC) and to document associated adverse effects. (3) Methods: Seventeen cases of histopathologically confirmed corneolimbal SCC in horses were retrospectively identified. Masses were surgically excised by keratectomy and/or conjunctivectomy under general anesthesia, followed by impla...
Tachycardia and muscle tremors following intravenous administration of detomidine to a horse undergoing standing surgery. Detomidine hydrochloride is an alpha adrenoceptor agonist that is commonly used in equine practice to provide sedation and analgesia for horses undergoing standing procedures. Reported effects following intravenous administration of detomidine in horses include bradycardia, bradyarrhythmias, transient hypertension, sweating, piloerection and dose-dependent sedation, ataxia and analgesia. This case report describes a novel response characterised by tachycardia and profound muscle tremors following the administration of intravenous detomidine to a horse undergoing a standing procedure.
Liposomal bupivacaine caudal epidural in horses results in adverse effects without analgesia. To evaluate the analgesic properties and adverse effects of liposomal bupivacaine administered via caudal epidural in horses. Methods: Pharmacodynamic study. Methods: A total of 10 healthy adult horses. Methods: Liposomal bupivacaine (10 mL; 1.3%) was administered into the caudal epidural space via an indwelling epidural catheter inserted to a length of 15 cm. Mechanical nociceptive threshold (MNT) testing with pressure algometry was used to measure analgesia at four anatomic locations for 72 h following injection. Physical examinations (including rectal temperature, heart rate, respirat...
Pharmacokinetics, pharmacodynamics, and local tolerance at injection site of penicillin and gentamicin administered by intravenous regional limb perfusion in standing horses: comparison between weightbearing and flexed limbs. Intravenous regional limb perfusion (IVRLP) of antibiotics is a therapeutic method used to treat distal limb infections in horses. The objectives of this study were to determine the pharmacokinetic parameters and tolerance of sodium benzylpenicillin (NaBP) administered via IVRLP; to compare the feasibility, tolerance, and efficacy of performing IVRLP on a flexed limb versus a weightbearing limb; and to predict the efficacy of IVRLP using gentamicin or NaBP. A prospective crossover study was conducted with six horses, each undergoing four phases of antibiotic infusion (gentamicin at 2.2 mg/kg ...
Adverse Effects of Antimicrobial Drugs Use in Horses. Antimicrobial drug therapy in horses can lead to adverse effects across multiple body systems, with specific age groups, such as foals, at particular risk. Certain antimicrobial drugs, such as penicillins, aminoglycosides, macrolides, tetracyclines, and trimethoprim-sulfonamide combinations, are commonly implicated. This review explores the mechanisms behind these adverse reactions, emphasizing the importance of judicious antimicrobial drug use. This review also underscores the need for a centralized pharmacovigilance system to improve drug safety and adverse event reporting for veterinary med...
BCG Immunotherapy in Equine Sarcoid Treatment: Mechanisms, Clinical Efficacy, and Challenges in Veterinary Oncology. Equine sarcoids are the most common dermatological neoplasm in horses worldwide, associated with bovine papillomavirus (BPV) infection and characterized by high recurrence rates after conventional therapies. Bacillus Calmette-Guérin (BCG) immunotherapy has historically been used for sarcoid treatment, yet its role in contemporary veterinary oncology remains debated. This narrative review critically examines the immunological mechanisms, clinical efficacy, and limitations of BCG in equine sarcoid therapy, while integrating insights from comparative oncology and One Health perspectives. A syste...
Adverse Effects and Drug Reactions in Equids. Adverse drug events (ADEs) are any harms caused by medical interventions used for treatment, prevention, or diagnosis. These events can happen due to human error or as unintended, harmful reactions to drugs when given at normal therapeutic doses. This review focuses on common ADEs associated with drugs frequently used in equine practice. Recognizing and understanding the manifestations of ADEs can help with early detection and more effective management, ultimately leading to better outcomes for equine patients. Additionally, knowledge of the potential harmful effects of drugs also aids in appr...
Antimicrobial prescribing guidelines for horses in Australia. The growing problem of antimicrobial resistance also affects equine veterinarians with increasing frequency. Antimicrobial stewardship and responsible prescribing are essential for a future in which effective antimicrobials are available, as it is unlikely that new antimicrobials will become available for use in horses. While antimicrobials are commonly used to treat equine infections, complications with therapy are also relatively common. Antimicrobial-associated diarrhoea, immune-mediated diseases, and nephrotoxicity have been reported as sequelae of antimicrobial therapy in equine practice....
Ivermectin toxicosis in a foal: Use of intravenous lipid emulsion therapy. 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...
Life-threatening anaphylaxis following antivenom administration in two patients with horse dander allergy. Antivenom is used to treat systemic envenomation and is immunoglobulin G raised from animals, mainly horses, inoculated by venom. Unassigned: We report two cases of life-threatening anaphylaxis following the administration of antivenom in patients with known horse dander allergy. Unassigned: A 14-year-old boy presented with redback spider envenomation. He had a known horse dander allergy. He received antivenom to treat severe pain and developed immediate severe anaphylaxis requiring endotracheal intubation and inotropic support. A 52-year-old man with horse dander allergy presented with suspec...
Oral cannabidiol increases thermal threshold in horses without physiologic adverse effects. 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...
The impact of transdermal application site on pharmacokinetics and selected pharmacodynamics of buprenorphine in horses. To assess absorption after transdermal application of buprenorphine to different sites and assess behavioral, antinociceptive and adverse effects. It was hypothesized that the dose and site of transdermal buprenorphine administration would influence absorption, plasma drug concentrations, physiological, antinociceptive and behavioral effects in horses. Methods: Two-part study; prospective randomized balanced three-way crossover (study 1) and single-dose (study 2) experimental study. Methods: Six (study 1) and eight (study 2) horses, aged 3-14 years. Methods: In study 1, horses were administere...
Canagliflozin: Pharmacokinetics, tolerability and glucose/insulin effects of supratherapeutic doses in healthy horses. Sodium-glucose co-transporter 2 inhibitors like canagliflozin (CFZ) have shown promise in preventing hyperinsulinemia-associated laminitis in horses, but data on pharmacokinetics, tolerability, and controlled studies are limited. This randomized, open-label, placebo-controlled, crossover study evaluated these aspects of CFZ treatment in eight healthy Standardbred mares. Each horse received single supratherapeutic oral doses of CFZ (1.8 mg/kg or 3.6 mg/kg) and placebo, with a two-week washout between treatments. A graded glucose infusion (GGI) was administered post-treatment to evaluate glu...
Injection site abscesses associated with commensal and environmental bacteria following intramuscular vaccination in horses. Five previously healthy horses in Korea, including a 19-year-old mixed-breed gelding, a 16-year-old mixed-breed mare, a 13-year-old Thoroughbred gelding, a 12-year-old Belgian warmblood mare, and a 12-year-old Andalusian mare, developed subcutaneous abscesses in the left neck after receiving intramuscular vaccination without prior skin disinfection. The vaccination used was Equivac® 2 in1, containing toxoid and cell-free extract. Within one week, the horses developed localised swelling and/or abscessation at the injection site. One case involved a ruptured abscess, while the others presente...
Mesenchymal Stem Cells in Veterinary Medicine-Still Untapped Potential. Mesenchymal stem cells (MSCs) hold significant therapeutic potential in veterinary medicine due to their regenerative and immunomodulatory properties. This review examines the clinical applications of MSCs across multiple animal species, including equine, canine, feline, and bovine medicine. MSC therapies have demonstrated promising outcomes in treating musculoskeletal disorders, osteoarthritis, inflammatory diseases, and tissue injuries, particularly in horses and dogs. In cats, MSCs show potential for managing chronic kidney disease, inflammatory bowel disease, and asthma, while in bovine me...
