Analgesia and restraint in horses, and analgesia and anaesthetic premedication in dogs and cats. Analgesia peaks between 10 and 20 minutes postadministration and persists for three to five hours.
Horses. Analgesia and restraint. When methadone is used in combination with acetylpromazine injection, it is an effective agent of restraint and analgesia, facilitating treatment of wounds, handling and loading of difficult animals, suturing, laryngoscopy, castration and minor surgical procedures. Following intravenous (IV) administration, the onset of action is rapid and clinical effect is usually sufficient to begin the procedure within three minutes. Horses rarely become recumbent or ataxic after methadone?acetylpromazine administration, even at high doses. Clinical doses produce a somnolent but aware state in which the animal is tractable, placid and sufficiently coordinated to minimise risk of injury to animal or operator. Methadone may be employed as a premedicant to xylazine sedation or barbiturate or ketamine anaesthesia to provide effective analgesia and restraint during painful procedures.
Dogs. Analgesia and premedication. Methadone Injection is used in premedication of barbiturate anaesthesia. Barbiturates have extremely poor analgesic properties, even at high dose rates. Methadone premedication of barbiturate anaesthesia smooths induction and greatly minimises the risk of drug toxicity by enabling the dose of barbiturate to be halved.
Cats. Methadone is used as a premedicant for inhalational anaesthesia. Compatability with acepromazine and propofol has been demonstrated. Repeat doses of methadone for analgesia can be given at three time points with 5 hour intervals.