How to Perform an Alfaxalone and Midazolam Co-induction Technique in a Premedicated Cat

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January 2026

In this VETgirl online veterinary continuing education video, Amanda M. Shelby, RVT, VTS (Anesthesia & Analgesia) demonstrates a co-induction drug technique, anesthetic machine preparation, and orotracheal intubation in a premedicated cat. Using the technique described by Lagos-Carvajal, et al., we demonstrate the smooth induction technique of an alfaxalone-midazolam intravenous induction in a premedicated cat. Check it out to learn how to maximize alfaxalone dose reduction using a low dose of midazolam!


Successful intubation is essential to patient safety by ensuring a patent airway for the delivery of oxygen and inhalant anesthetics. It also allows the anesthetist to monitor and assist ventilation, if necessary. Keys to successful intubation begins before administration of induction drugs with appropriate patient premedication and equipment preparation. It is essential to have your anesthetic machine and patient breathing circuit assembled and leak checked before inducing the patient. I am using pediatric-sized tubing in a circle system for this patient, but you could use a modified Bain circuit or Mapleson circuit designed as a non-rebreathing system. After leak testing, I applied a side-stream capnograph adapter to the patient breathing circuit. A laryngoscope (with a working light) along with various sizes of endotracheal tubes should be available; the integrity of their cuffs should also be confirmed prior to the procedure. Other supplies for intubation include sterile water-soluble lubricant for the cuff of the endotracheal tube and a tie to secure it in place.

This roughly 7-kg cat was premedicated with buprenorphine at 0.03 mg/kg and dexmedetomidine at 3 mcg/kg intramuscularly (IM) 20-30 minutes before induction. An intravenous (IV) catheter was placed in his cephalic vein. The co-induction strategy demonstrated here is based on a publication by Lagos et al which found 0.08 mg/kg of midazolam was the most effective dose (ED50) of midazolam that produced greatest dose reduction of the primary induction agent, alfaxalone. Here, we administer 2 mg (or 0.2 mL) of alfaxalone IV, which for this cat comes to dose per patient body weight of about 0.3 mg/kg, followed by midazolam at 0.08 mg/kg IV. Additional alfaxalone is available if needed to facilitate stress-free, smooth intubation. The patient noticeably relaxes. The assistant positions the patient’s head and neck, while the anesthetist applies a drop of lidocaine to each arytenoid. Notice movement of arytenoids demonstrates this patient is spontaneously ventilating on this induction combination. The anesthetist lubricates the cuff of the endotracheal tube and uses the laryngoscope to visual the tracheal opening through the arytenoids. The endotracheal tube is positioned above the arytenoids and when the patient takes a breath, using very gentle pressure, the endotracheal tube is advanced into the trachea to the pre-determined depth of approximately 15 cm in this patient. The endotracheal tube is secured in place and the patient attached to the breathing circuit. While we don’t show how to inflate the cuff in this cat, please make sure to appropriately inflate the cuff, being cautious not to overinflate! Oxygen would be started and the patient would be continuously monitored by the anesthetist throughout the procedure.

So, there you go, we demonstrated a co-induction technique with alfaxalone and midazolam in a premedicated cat and you got the extra benefit of seeing a machine set up and leak test with a pediatric circle system and intubation!

References:
Lagos-Carvajal A, Queiroz-Williams P, da Cunha A, et al. Determination of midazolam dose for co-induction with alfaxalone in sedated cats. Vet Anaesth Analg 2019;46(3):299-307.

 

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