Feline Anesthesia
Richard M. Bednarski, DVM, MSc The Ohio State University College of Veterinary Medicine Current Issues in Feline Anesthesia
• Chemical Restraint Protocols
• Trap, Neuter, Release Anesthetic Protocols • Early age spay/castration protocols
• Analgesia and Analgesics
Sedation/Moderate Restraint – Acepromazine
– Alpha 2 agonists: Medetomidine, Xylazine – Neuroleptanalgesia
– Ketamine (low dose) – Telazol (low dose)
Acepromazine • Mild sedation
• Vasodilation • Antiarrhythmic • Antiemetic
• Combines well with opioids to produce moderate sedation and restraint
• 0.05 -0.2 mg/kg
Alpha 2 Agonists: Xylazine, Medetomidine • Moderate sedation and chemical restraint • Reversible
• Combine well with opioids • Vomiting
• Cardiovascular alterations
Medetomidine (Domitor)
• Cardiovascular effects make it best for use in young, healthy cats • 30 minute -1.5 hour duration
• Reversible with Atipamezole (Antiseden)
• Can be combined with opioids and/or ketamine for moderate restraint to surgical anesthesia
Medetomidine (Domitor) in Cats
• Dosage: 40 - 100 µg/kg for moderate to significant restraint • Duration of action: 30-90 minutes
Midazolam • Water soluble benzodiazepine
• Very similar pharmacokinetics and pharmacodynamics to Diazepam
• Minimal cardio-respiratory side-effects • Rarely useful by itself for sedation
– Best when combined with an opioid for mild sedation/restraint
Midazolam
• Useful when acepromazine is contraindicated • Most useful in middle aged to older animals
– Sedation generally better than in young healthy animals
• Useful in sick or debilitated animals
Neuroleptanalgesia • One of the following
– Acepromazine, Alpha 2 Agonist, Midazolam combined with one of the following
– Morphine, Hydromorphone, Oxymorphone, Buprenorphine, Butorphanol
Opioids • Agonists
– Morphine, hydromorphone, oxymorphone, fentanyl, meperidine
• Agonist/Antagonists
– Butorphanol, Buprenorphine, Pentazocine • Antagonists
– Naloxone
Parenteral Opioid Dosages (mg/kg) • Morphine: 0.2 - 1.0
• Hydromorphone: 0.02 - 0.1 • Fentanyl: 0.002
• Fentanyl Infusion: 1 - 6 µg/kg/hr • Oxymorphone: 0.02 - 0.1
Parenteral Opioid Dosages (mg/kg) • Butorphanol: 0.2 -0.8 – 45 minutes duration • Buprenorphine: 0.005 - 0.02 – 6 - 8 hrs duration Tiletamine/Zolazepam
• 50:50 combination of a benzodiazepine tranquilizer and a dissociative anesthetic
• Variable dosages for mild sedation to “surgical” anesthesia (2 -6 mg/kg)
– Prolonged recovery at the higher dosages
• Useful prior to gas anesthesia or combined with other chemical restraint drugs
Short Term Injectable Anesthesia in Cats • Acepromazine, Opioid, Ketamine
• Diazepam and Ketamine • Propofol
• Thiopental
Feral Cat Trap/Neuter/Return (TNR) Anesthesia • IM administration
• Rapid and predictable surgical anesthetic duration and effect • Economical
• Reversible
• Wide safety margin
Feral Cat TNR Anesthesia • Telazol, Xylazine, Ketamine (TKX)
• Medetomidine, Ketamine, Butorphanol
Telazol/Ketamine/Xylazine
• To one vial of Telazol add 4 ml ketamine and 1 ml 10% (LA) Xylazine
• Dose
– 0.015 ml/lb body weight
• Note: Accurate body weight is essential to safe dosing
Medetomidine, Ketamine, Butorphanol • Medetomidine: 60 µg/kg, IM
• Ketamine: 5 mg/kg, IM • Butorphanol: 0.2 mg/kg, IM
– Can be mixed in same syringe
– Atipamezol to reverse medetomidine
• Wait at least 45 minutes after medetomidine
Early Age Spay/Neuter Anesthesia • IM administration
• Rapid and predictable surgical anesthetic duration and effect • Economical
• Reversible
• Wide safety margin
Early Age Spay/Neuter Anesthesia • Tiletamine/Zolazepam
– Useful alone in most males but occasionally must be supplemented with inhalants
– Must be supplemented with inhalants for ovariohysterectomy – Recovery can be prolonged
Early Age Spay/Neuter Anesthesia
• Mask with isoflurane or sevoflurane followed by intubation
– Uncuffed tube provides relatively larger diameter airway
• Can administer butorphanol for post operative analgesia • Advantage is relatively quick and predictable recovery time
Behavioral Response to Pain • Anxiety and Fear
• Depression and lethargy • Sleeplessness
• Quiet and withdrawn – Especially Cats • Inappetence
• Vocalization
Pain Assessment • Subjective
– Anthropomorphism: We assume if it would be painful to us it would be painful to the animal
– Obvious examples of painful procedures
excisions, amputations (including onychectomy) Analgesic Drugs • Opioids • NSAID’s • Local Anesthetics • Alpha 2 agonists • Ketamine • Others Buprenorphine • Oral administration – 10 µg/kg BID
– Approximately 0.1 ml from a TB syringe per 3 kg body weight
• Excellent acceptance by cats – Good owner compliance
Transdermal Fentanyl • Dog VS. Cat
• Location of Patch
• Warm water blankets, forced air warmers • Abuse Potential
Transdermal Fentanyl • Duragesic Patch - Janssen Pharmaceutica • 25, 50, 75, 100 µg/hr strength
• Onset
– Cats: 10 - 18 hrs – Dogs: 18 - 24 hrs
• Duration: 3 days/patch
NSAID’S • Inhibit cyclooxygenase
– Prostaglandin synthesis is reduced • COX - 1 (constitutive): Normally present
– Involved in normal renal, GI, platelet function • COX -2 (inducible): Induced by tissue damage
– Inflammation and pain
NSAID’S Dosages (mg/kg) • Carprofen: 4.0 given once
• Ketoprofen: 2.0 SC, p.o. initially followed by 1.0 daily for 5 days
• Meloxicam: 0.2 SC, p.o. initially followed by 0.1 daily for 2 - 3 days
Local Anesthetic for Declaw Procedure • Subcutaneous injection just proximal to carpus
– Palmar and Dorsal surfaces
• Ropivacaine (Naropin) or Bupivacaine – Use the 0.2 % or 0.25% preparation – Dosage = 2.0 mg/kg
– Approximately 1.5 ml per leg per 3 kg cat
Short-term Injectable Anesthesia in Cats • Acepromazine/Opioid and Ketamine
• Thiopental • Propofol
Long-term Injectable Anesthesia in Cats • High dose ketamine
• High dose ketamine with acepromazine • Medetomidine and ketamine
• Medetomidine and ketamine with opioid • Telazol • Telazol/Ketamine/Xylazine • Propofol Infusion Inhalation Anesthetics • Isoflurane • Sevoflurane • Halothane • Desflurane • Nitrous Oxide Anesthetic Induction • Mask or Chamber • Thiopental
• Diazepam or Midazolam and Ketamine • Propofol
Feline Intubation • Laryngoscope
– Straight Blade is preferable • Stylet
