A newer drug, propofol (a nonbarbiturate hypnotic), has become the "injectable of choice" for certain procedures for many veterinarians, as it is quick-acting, offers a rapid recovery period, and rarely induces drug aftereffects.
Dosage for propofol, as for all licensed drugs, is governed by the FDA:
- (2) Cats.
(i) The drug is indicated for use as an anesthetic as follows: As a single injection to provide general anesthesia for short procedures, for induction and maintenance of general anesthesia using incremental doses to effect, and for induction of general anesthesia where maintenance is provided by inhalant anesthetics.
(ii) The drug is administered by intravenous injection as follows: For induction of general anesthesia without the use of preanesthetics the dosage is 8.0 to 13.2 milligrams per kilogram (3.6 to 6.0 milligrams per pound). For the maintenance of general anesthesia without the use of preanesthetics the dosage is 1.1 to 4.4 milligrams per kilogram (0.5 to 2.0 milligrams per pound).
The use of preanesthetic medication reduces propofol dose requirements.
(iii) Adequate data concerning safe use of propofol in pregnant and breeding cats have not been obtained. Doses may need adjustment for geriatric or debilitated patients. Federal law restricts this drug to use by or on the order of a licensed veterinarian.
[Title 21, Volume 6, Parts 522]
[Revised as of April 1, 2000]
Inhalant Anesthetics
Isofluorane revolutionized veterinary anesthesia, because of its safety (particularly with older or compromised patients), rapid recovery of the patient after surgery, and the fact that it is not likely to induce nor exacerbate heart arrhythmias. Isofluorane recently lost its patent, so is becoming less expensive than newer inhalants, and is still considered the anesthetic of choice in veterinary medicine for pregnant animals (including c-sections) and for animals with heart problems. Sevoflurane is relatively new, costing about four times more than isofluorane. Halothane costs even less than Isofluorane, and is still in popular use. Both isoflurane and halothane require the use of a precision vaporizer for measuring the appropriate deliverance of anesthetic. Your veterinarian can (and should) provide information as to which anesthetics he/she uses and why.
It has been said that there is no such thing as the perfect anesthetic, and there is always potential for risk with any of them. It therefore behooves us to do our homework prior to allowing any procedure requiring anesthesia, and to insist on a pre-anesthetic blood screening. This precaution is not a guarantee by any means (for instance, Cardiomyopathy will not show up on a blood panel), but it can help your veterinarian determine what is the best anesthetic or combination of anesthetics for your cat. Certain conditions may not obviate the need for anesthesia, but other precautions such as heart monitoring and/or oxygen assistance can be added for additional safety.
In my opinion, the most important thing you can do as part of your cat's health team, is to know your cat's history, and to remind your veterinarian of certain conditions when contemplating procedures requiring anesthesia or sedation. For example, heart conditions, asthma or liver or kidney insufficiency would preclude the use of certain anesthetic agents. Often busy veterinarians do not have a photographic memory of the preexisting conditions of all their patients, and such diagnoses sometimes get buried in charts. Most vets will appreciate your reminding them that Charlie has asthma, so don't be afraid to speak up.
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