No abstract

Many surgical and diagnostic procedures can be performed safely and humanely in conscious horses by using a combination of sedation, analgesia and local anaesthetic techniques. This article discusses sedatives and analgesics, including drugs that are administered intravenously, intramuscularly, orally or transmucosally. Drugs administered by infiltration, and/or the epidural, perineural or intra-articular routes to provide local analgesia will be discussed in a second article, to be published in a subsequent issue of In Practice.

Joanne Michou graduated from the University of Cambridge in 2006. After time as an equine intern and two years in mixed practice in Suffolk, she undertook a senior clinical training scholarship in anaesthesia and analgesia at Cambridge. She is currently the anaesthetist at Pride Veterinary Centre. She is studying towards the European diploma in anaesthesia and analgesia. Local anaesthetic techniques are valuable adjuncts to sedation and systemic analgesia, facilitating surgery and diagnostic procedures in standing conscious horses. Local anaesthetic techniques are useful in preventing nociception in order to perform surgery, to minimise movement, aid even weight bearing and for postoperative analgesia. This article discusses choice of drugs and local techniques, and accompanies an article on the systemic drugs used for sedation and analgesia published

An eight-year-old male entire crossbreed dog, evaluated for resection of a mass at the base of the tail, underwent general anaesthesia for CT. Following preanaesthetic medication of 0.2 mg/kg butorphanol and 0.015 mg/kg acepromazine intravenously, anaesthesia was induced with 2 mg/kg alfaxalone and 0.3 mg/kg midazolam intravenously. Anaesthesia was uneventful, although during recovery the dog showed prolonged excitatory signs consisting of intermittent opisthotonic posture, limb dystonia, myoclonic jerks, paddling movements of all limbs, oculogyric movements and excessive vocalisation consistent with drug-induced extrapyramidal side effects (EPS). EPS lasted 25 hours and did not cease after administration of antiepileptic drugs, but rapidly resolved after administration of chlorphenamine, an H1 antihistamine with anticholinergic activity. This report provides proposed mechanisms for the pathogenesis of these neuroanaesthetic EPS, frequently termed excitatory phenomena, and reports a successful treatment of prolonged EPS in a dog by blockade of muscarinic acetylcholine receptors.

No abstract