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Isoflurane Anesthesia

Randy Walker DVM

About Anesthesia...

At Sun Lakes Animal Clinic we are very proud of our extremely low incidence of anesthetic complications. We attribute our excellent anesthetic record to several factors, the main ones being: (1) we attempt to screen each patient for potential risks prior to anesthesia; (2) we use only the safest anesthetic agents available (mainly isoflurane); and (3) we pursue very careful monitoring both during the procedure and afterward while the patient is waking up.

Are There Really Differences In Anesthetics?

Yes. Anesthetics will vary in how they are given, in what effects they have, in how they are eliminated from the body, and in their safety factor. In general, anesthetics are given either intravenously (meaning to give an injection in the vein) or in the gas form through an endotracheal tube.

Briefly, What Are The Advantages & Disadvantages Of Injectable Anesthetics?

The main advantages of injectable anesthesia are that it is relatively cheap, convenient, and easy to administer. The disadvantages of injectable anesthesia are that it's harder to control the depth and duration of anesthesia and that the time it takes for the patient to wake up is usually longer than with gas anesthesia. It should be noted, however, that injectable anesthesia is considered to be safe when used with care.

Briefly, What Are the Advantages & Disadvantages of Gas Anesthesia?

The advantages of gas anesthesia are that the depth and duration of anesthesia can be controlled very precisely. Most patients wake up from gas anesthesia much quicker and have fewer adverse side-effects. The disadvantage of gas anesthesia is that gas anesthesia is more expensive and there is also a significant investment in the equipment used to administer it which is reflected in higher veterinary costs.

Are There Really Any Differences In Gas Anesthetics?

Yes. There are differences in duration of action, control over side effects, ability to control the depth of anesthesia, and general safety factors between the various gas anesthetics. This is not to say, of course, that any of the veterinary approved gas anesthetics are considered unsafe when properly used.

Can Any Of The Gas Anesthetics Be Considered Superior?

Yes. I personally believe that Isoflurane is superior to other gas anesthetics.

Does Sun Lakes Animal Clinic Use Isoflurane Anesthesia?

Yes. At Sun Lakes Animal Clinic we use Isoflurane almost exclusively.

What is Isoflurane?

Isoflurane is a relatively recently developed gas anesthetic which has gained rapid widespread popularity in human medicine due to its increased safety and minimal side effects. It is now very popular in veterinary medicine for the same reasons.

What Are The Main Differences You Have Seen With Isoflurane As Opposed To The Older Anesthetics?

The main differences we have noted are that patients anesthetized with isoflurane have notably stronger vital signs during procedures and rarely have anesthetic complications. Its my personal experience that patients under isoflurane "do better'' during the procedure and wake up more rapidly thereafter (on average) than do patients anesthetized with other agents.

How Safe Is Isoflurane?

We believe isoflurane is one of the safest anesthetics on the market for both the patients and for the operating room personnel (who do get exposed to low levels of the gases occasionally). For this reason, isoflurane is our standard anesthetic for routine use at Sun Lakes Animal Clinic.

What Are The Negative Aspects Of Isoflurane?

The main "negative" aspect encountered with isoflurane is the cost of the agent. Depending on what kinds of deals the drug companies are offering at any given time, isoflurane will cost anywhere from 5-10 times as much as the next highest priced anesthetic agent. As with everything else in life, these costs get passed on to the consumer resulting in higher veterinary bills. Other than this, isoflurane has no drawbacks that aren't encountered with other anesthetics and in fact, the drawbacks encountered with isoflurane are notably less than with other anesthetics.

Is Isoflurane FDA Approved And Marketed For Use In Dogs Cats?


Is There Ever A 100% Guarantee That My Pet Will Not Have Complications Under Anesthesia?

No. As with many things in life, there is never a 100% guarantee that nothing can go wrong. It is primarily for this reason that veterinarians take many safety precautions including physical examinations, appropriate lab tests and other diagnostic procedures beforehand, monitoring the patient's vital signs extensively during the procedure, and careful monitoring of the patient upon waking up from anesthesia. Taking these precautions accounts for much of the tremendous success record with anesthetized procedures we have had here at Sun Lakes Animal Clinic.

Generally Speaking, What Safety Precautions Can Be Taken Before My Pet Receives Anesthetic?

We recommend a routine blood serum profile to check the health of the organs (kidneys, liver, etc), for all patients 8 years old and older as a general rule.  Also, if abnormalities are noted on the physical exam (such as heart murmurs, abnormal lung sounds, etc), we will often recommend these be evaluated further before anesthetics are administered.

What Are My Responsibilities Before My Pet Receives Anesthesia?

We advise the patient be held off food (given nothing to eat) after 10:00 p.m. the evening before (for a fasting period of 10-12 hours) and water to be withheld beginning about two hours prior to anesthesia. Of course, we often perform anesthesia on unfasted patients on an emergency basis when necessary but we always prefer the patient be fasted when possible. Also remove all flea collars and prevent exposure to insecticides such as flea sprays, etc. and leave them off until two days after anesthesia because they can sometimes react adversely with anesthetics.

What Are My Responsibilities After My Pet Receives Anesthesia?

We recommend that the pet not be given anything to eat for several hours after waking up. Then, give the pet a very small amount of food and observe them for about an hour afterward to make sure they don't become nauseous. If no nausea is observed you can feed a small meal at that time and go back on regular feeding the next day unless you have received other instructions.

- Randy Walker DVM
Sun Lakes Animal Clinic
May 16,2004

"Until one has loved an animal, a part of one's soul remains unawakened."
- Anatole France, 1921 Nobel Prize Speech -

Titlebar Image: The Gentle Doctor, 1937-38 by Christian Peterson (U84.179) - Iowa State University