What type of anesthesia is used for spaying cats?

Anesthesia for Spaying Cats

Cats undergoing spay procedures typically receive multimodal anesthesia consisting of injectable premedication followed by inhalational anesthetics, with local anesthetic blocks for optimal pain control.

Premedication and Induction

• Premedication is administered to most cats (95.1%) prior to induction of anesthesia for spaying procedures 1

• Common premedication options include:

  • Acepromazine, which helps control fractious animals during examination and treatment, and enhances the effects of other anesthetics 2
  • Benzodiazepines such as midazolam (0.05-0.1 mg/kg) for sedation and as part of induction 3
  • Opioids for preemptive analgesia, administered at the time of anesthetic induction 4

• Induction agents commonly used include:

  • Propofol, which has a rapid onset and recovery profile 3
  • Ketamine (1-2 mg/kg) in combination with midazolam, which maintains systemic vascular resistance and provides analgesia 3, 5
  • Tiletamine-zolazepam combinations, which provide rapid induction of immobilization, unconsciousness, and muscle relaxation with an anesthesia duration of 30-45 minutes 6, 5

Maintenance Anesthesia

• Sevoflurane is preferred for maintenance due to its rapid onset and offset, as well as less airway irritation 3
• Intravenous catheters are placed in most cats (94.6%) undergoing ovariohysterectomy to provide vascular access for fluid therapy and emergency medications 1
• Orotracheal intubation is performed in the vast majority (98.2%) of cats undergoing ovariohysterectomy to protect the airway and deliver inhalational anesthetics 1

Pain Management

• Almost all veterinarians (99.7%) administer an opioid and/or a non-steroidal anti-inflammatory drug perioperatively for cats undergoing spay procedures 1
• Local anesthetics such as lidocaine and bupivacaine are frequently used as part of a multimodal analgesic approach:
  • Lidocaine has a fast onset (10-15 min) and intermediate duration (60-120 min) 7
  • Bupivacaine has a slower onset (20-30 min) but longer duration (240-360 min), making it ideal for postoperative pain control 7
  • Local anesthetic blocks reduce the amount of general anesthetic needed and provide optimal pre-emptive analgesia 8

Monitoring and Support

• Standard monitoring includes:
  • Vital signs assessment including color of skin and mucosae
  • Breathing pattern and frequency evaluation at regular intervals
  • Body temperature maintenance throughout the procedure 4
• Subcutaneous fluids at body temperature are often administered to prevent dehydration, especially during longer procedures 4

Recovery

• Postoperatively, cats should be recovered in a warm and quiet environment and evaluated frequently until they are sufficiently awake 4
• Recovery quality varies with the anesthetic protocol used:
  • Tiletamine-zolazepam combinations typically result in longer recovery times 5
  • Protocols including opioids generally allow for faster recovery, especially when reversal agents are used 6, 5

Key Considerations

• The anesthetic protocol should have a wide safety margin for cats of all ages 6
• Effective protocols are economical, easy to use with small injection volumes, have rapid onset and offset, and possess good analgesic properties 6
• Older cats may require special consideration due to limited homeostatic reserves and increased sensitivity to anesthetic agents 8
• Administration of excessive doses and accidental intravenous administration of local anesthetics are common causes of systemic toxicity, so doses should be calculated carefully, especially for small cats 7