Opioids in horses refer to a class of drugs that interact with opioid receptors in the central nervous system to produce analgesic effects. These substances are used in veterinary medicine for pain management, sedation, and anesthesia in equine patients. Opioids such as morphine, butorphanol, and buprenorphine are commonly administered to horses to alleviate pain associated with surgical procedures, injury, or chronic conditions. The pharmacokinetics and pharmacodynamics of opioids in horses can vary, influencing their efficacy and safety profiles. This topic includes a collection of peer-reviewed research studies and scholarly articles that explore the use, effects, and considerations of opioid administration in equine veterinary practice.
Combie J, Blake JW, Ramey BE, Tobin T.Morphine was detected in equine biological fluids by a combination of liquid-liquid extraction and column chromatography, followed by derivatization and gas-liquid chromatographic assay, using electron capture detector. Recovery of morphine from the equine biological samples was poor. However, despite an overall recovery of less than 20%, this method had a detection limit of 0.2 ng/ml. Addition of 5,000 U of bovine liver beta-glucuronidase/ml of urine enabled detection of the drug in urine for up to 144 hours after horses were given 0.1 mg of morphine/kg of body weight. Morphine was found for ...
Combie J, Shults T, Nugent EC, Dougherty J, Tobin T.The locomotor responses of horses given morphine and fentanyl were blocked or lessened by administration of naloxone or acepromazine. Naloxone given at the dosage of 0.015 mg/kg completely blocked the locomotor activity induced in horses given fentanyl (0.020 mg/kg of body weight). The locomotor stimulation produced by morphine given at the dosage of 2.4 mg/kg was reduced by 75% of naloxone (0.020 mg/kg). Acepromazine partially blocked the locomotor responses to fentanyl and morphine. This blockade activity reached its peak about 30 minutes after acepromazine was given (IV) and lasted more tha...
Alexander F.The effect of morphine, Tinct. opii, loperamide, pethidine and atropine on intestinal transit and the faecal and urinary excretion of water and electrolytes was studied in ponies. The rate of passage of a particulate marker was slowed by morphine, hastened then slowed by loperamide and Tinct. opii, and hastened by atropine. The liquid marker was slowed by Tinct. opii and hastened then slowed by the other drugs. Only loperamide decreased the faecal sodium excretion. This drug also decreased faecal water and weight; it appeared worthy of clinical trial in diarrhoea. Tinct. opii decreased by morp...
Muir WW, Skarda RT, Sheehan WC.The cardiopulmonary effects of the narcotic agonists morphine, meperidine, oxymorphone, and methadone and of the partial agonist pentazocine were examined in the pain-free adult horse. The drugs produced dysphoric followed by euphoric effects. Increases in heart rate, arterial blood pressure, and cardiac output were observed in all horses with all drugs. Arterial blood pressure remained increased even after heart rate and cardiac output had returned to base-line values. Respiratory rate generally remained unchanged or increased shortly after drug administration and then decreased insignificant...
Combie J, Shults T, Nugent EC, Dougherty J, Tobin T.The locomotor responses of horses given morphine and fentanyl were blocked or lessened by administration of naloxone or acepromazine. Naloxone given at the dosage of 0.015 mg/kg completely blocked the locomotor activity induced in horses given fentanyl (0.020 mg/kg of body weight). The locomotor stimulation produced by morphine given at the dosage of 2.4 mg/kg was reduced by 75% of naloxone (0.020 mg/kg). Acepromazine partially blocked the locomotor responses to fentanyl and morphine. This blockade activity reached its peak about 30 minutes after acepromazine was given (IV) and lasted more tha...
Tulamo RM, Raekallio M, Taylor P, Johnson CB, Salonen M.Both morphine and physiologic saline injected intra-articularly into healthy equine tarsocrural joints induced a release of large molecular size proteoglycan (PG) subunits into the synovial fluid (SF) analysed 24 h postinjection. High-performance liquid chromatography (HPLC) with a size-exclusion column was used to assess the high molecular weight proteoglycans in equine synovial fluid (SF). The PG peaks of SF samples eluated separately from SF hyaluronate and other molecular components of the SF in the HPLC chromatographies indicating no interaction between hyaluronate and PG in the SF. Indiv...
Wang CC, Hartmann-Fischbach P, Krueger TR, Wells TL, Feineman AR, Compton JC.Dermorphin and HYP(6) -dermorphin are hepta-peptides and natural opioids originally isolated from the skin of South American frogs. They are more potent than morphine but less likely to produce drug tolerance and addiction. These properties make them ideal candidates for the doping of racehorses to enhance performance during competition. Dermorphin was recently classified as a Class I drug by Racing Commissioners International (RCI), indicating that it is a banned substance in equine athletes. To enforce this ban, a fast and sensitive method was developed for dermorphin and HYP(6)-dermorphin a...
Schwarzbach SV, Melo CF, Xavier PLP, Roballo KC, Cordeiro YG, Ambrósio CE, Fukumasu H, Carregaro AB.Osteoarthritis (OA) is one of the main locomotor disorders in horses. Although nonsteroidal anti-inflammatory drugs are the first-line treatment for OA, opioids could also be used. In previous studies, opioids showed promising anti-inflammatory and analgesic effects. In this study, we aimed to investigate the effects of two opioids (morphine and methadone) against inflammation in lipopolysaccharide (LPS)-stimulated synoviocytes by analyzing microsomal prostaglandin E synthase-1 (mPGES-1) and prostaglandin-endoperoxide synthase 2 (PTGS2) expression. Synoviocytes were obtained from the joints at...
Thomasy SM, Moeller BC, Stanley SD.To compare the density and binding characteristics of opioid receptor subtypes in horse, rat, and guinea pig cerebral cortex and cerebellum. Methods: Prospective receptor binding study. Methods: Whole brains were obtained from four neurologically normal adult horses during necropsy. Rat and guinea pig brains were obtained commercially. Methods: The cerebellum and cerebral cortex were dissected from each brain, and tissue homogenates prepared. A radioligand binding technique with the highly selective ligands [(3)H]-DAMGO, [(3)H]-U69593, and [(3)H]-DPDPE was used to identify the mu- (mu), kappa-...
Webster A, Pezzanite L, Hendrickson D, Griffenhagen G.Equine practitioners frequently inject local anaesthetics (LA) intra-articularly in both diagnosis of lameness and for pain management intra- or post-operatively with synovial endoscopy. Recent reviews of the human and veterinary literature support the concept that chondrotoxicity of LA on joint tissues depends on the type of drug, dose administered, and duration of exposure. The purpose of this review is to summarise the current literature describing intra-articular local anaesthetic use, including both in vitro and in vivo studies, and to draw some comparisons to literature from other specie...
Hovda LR.This article provides information on the toxicity of some therapeutic drugs, illicit drugs, and supplements. Medications in the therapeutic section are grouped into antibiotics, antipsychotic agents, bronchodilators, nonsteroidal anti-inflammatory drugs, opioids, and sedatives/tranquilizers. The section on illicit drugs and supplements provides information on more specific medications including commonly used or abused human medications and a few that are available only from Internet compounding pharmacies. Many drugs and supplements can be either therapeutic or illicit depending on the dosage ...
Dzikiti TB, Maney JK, Thorogood J, Segabinazzi L, Peterson E, Dzikiti LN, Escobar A.Intravenous infusions of alpha-2 adrenoceptor sedatives and opioids can potentially facilitate surgery in donkeys while standing. Literature on this subject matter is scant. Objective: Evaluation of efficacy of sedation from α -adrenoceptors (dexmedetomidine or xylazine) and butorphanol during ovariectomy in standing donkeys. Methods: Randomised, masked in vivo experiment. Methods: Thirteen female donkeys were sedated with butorphanol (0.05 mg/kg bwt followed by 0.5 mg/kg bwt/h) IV. Concomitantly, 6 of the 13 jennies were sedated with dexmedetomidine 2.5 mcg/kg bwt followed by 2.5 mcg...
Haralambus R, Juri M, Mokry A, Jenner F.Effective management of postoperative pain is essential to ensure patient welfare, reduce morbidity and optimize recovery. Opioids are effective in managing moderate to severe pain in horses but concerns over their adverse effects on gastrointestinal (GI) motility and associated increased colic risk limit their widespread use. Studies investigating the impact of systemic opioids on both GI motility and colic incidence in horses have yielded inconclusive outcomes. Therefore, this retrospective study aims to assess the influence of systemic administration of butorphanol, morphine, and methadone ...
