Depending on the procedure, propofol can be used as a single agent with or without additional delivery by bolus or constant-rate infusion (CRI). A propofol product with an extended shelf life (Propoflo-28, abbottanimalhealth.com) has recently been approved for use in veterinary patients. However, this product contains the preservative benzyl alcohol and therefore has not been labeled for CRI, bolus administration, or use in cats.
For patients undergoing short but potentially painful procedures, administration of propofol following premedication with an opioid (eg, butorphanol or hydromorphone) would be appropriate. (Note that propofol has no intrinsic analgesic properties.) Propofol may also be administered following a nonanalgesic sedative (eg, acepromazine). With sedative or opioid administration, lower doses of propofol and extended anesthetic duration are possible. Long-duration CRIs of propofol in cats may cause formation of Heinz bodies; however, this should not be a problem if the procedure takes less than 15 minutes.2,3 Propofol should always be given to effect.
Propofol Dose Schedule
- Recommended dose in dogs and cats is approximately 6 mg/kg IV given to effect:
- Dose may be decreased (closer to 3–4 mg/kg IV) in patients that have been:
—Premedicated with an opioid:
Butorphanol 0.2 mg/kg IM or
Buprenorphine 0.02 mg/kg IM or
Hydromorphone 0.1 mg/kg IM
—Premedicated with a sedative:
Acepromazine 0.02 mg/kg IM or
Dexmedetomidine 5–15 µg/kg IM - After propofol induction, can keep patient anesthetized with:
—Additional propofol boluses of approximately 0.5–1 mg/kg IV
—CRI propofol at 0.1–0.4 mg/kg/min
—Gas anesthetics
2. Dexmedetomidine & Ketamine +/- Opioid
The combination of an α2-agonist such as dexmedetomidine and ketamine is commonly used in companion animals. Administration of these 2 drug classes produces reliable results, provides analgesia, and allows intramuscular administration, which can be particularly useful for some patients. Recent studies have shown that a combination of dexmedetomidine (a common a2-agonist), ketamine, and an opioid can provide smooth and rapid anesthesia (<10 minutes).4
Traditionally, anesthetists use caution when reversing dexmedetomidine after combination with ketamine due to concerns about an agitated or rough recovery associated with solo use of ketamine (a dissociative anesthetic). However, a recent study showed that when low doses of ketamine were used (3 mg/kg with dexmedetomidine), reversal with atipamezole resulted in smooth recoveries.4 However, reversing dexmedetomidine also reverses its analgesic properties.
Following anesthetic induction, patients should be monitored for hypoventilation and the need for oxygen supplementation or intubation, especially if there are underlying airway concerns. If this drug combination results in inadequate anesthesia, additional gas anesthesia (eg, isoflurane) may be administered. α2-Agonists should be used with caution in patients with significant cardiovascular disease.
Dexmedetomidine/Ketamine Dose Schedule
- For both dogs and cats:
Dexmedetomidine 5–15 µg/kg IM
Plus
Ketamine 3–5 mg/kg IM
Plus/Minus
Opioid:
Butorphanol 0.2 mg/kg IM or
Buprenorphine 0.02 mg/kg IM or
Hydromorphone 0.1 mg/kg IM - In dogs, dexmedetomidine can be reversed with atipamezole
at 150 µg/kg IM or with a volume (mL) of atipamezole equal
to the volume of dexmedetomidine given.