Veterinary anaesthesia
ANAESTHESIA (pronounce An-S-theesee-ya). You may have heard of spaying, neutering or desexing clinics. Or you might have a surgery appointment for your cat or dog. Many people like to have an idea of what is going to happen, what to expect and what complications might occur.
The steps leading to the preparation of an animal for anaesthesia usually include some type of exam which can be very detailed with blood work, or very cursory, as in the case of field clinics. Veterinarians generally like to have as healthy an animal as possible when subjecting them to anaesthesia and surgery – at least a good body condition and nice pink mucous membranes in a bright and energetic animal.
Preparation most often involves a medication called sedation which takes away stress from the animal as it is in a new surrounding with new people. Too much stress can adversely affect the animal, the action of the medication and the animals response to that medication. This medication gives the veterinary team a calm and settled animal to further prepare, usually in the form of placing an intravenous (IV) catheter or cannula. Most anesthetic medication is provided by, or under supervision, of a veterinarian through this IV catheter, or it is breathed in with the help of an anaesthesia machine.
Anaesthesia is the process and specific medications involved in making an animal unconscious. Performing this professional procedure requires very specific, intensive and technical training, and the medications are under strict access and control – including who can order them, receive them and administer them.
Unconscious means “knocked out”, or in a “deep sleep”. Sometimes the popular expressions are confusing. In human medicine the term is called “put to sleep”. But we have to be careful because in veterinary medicine we have a procedure of humane death called euthanasia and sadly the term “put to sleep” is commonly used for that procedure. Quick, painless, humane death is distinctly different from anaesthesia.
When an animal is under anaesthesia we want them unconscious – feeling no pain – not responding except for very deep reflexes – and, most importantly, we want them to wake up. Wake up when we want, and not before.
Unfortunately it took a long time for professionals to catch on to the usefulness and value, not to mention the humaneness, of anaesthesia. Our ancestors kind of plowed forward with surgery – recognising the value of this – and only slowly allowing the developing procedure of anaesthesia to follow. In veterinary medicine we still are catching up with one of the main reasons for anaesthesia in performing procedures, and that is the alleviation of pain.
All animals, birds, fish and reptiles benefit from anaesthesia when procedures are performed. Anesthesiology fortunately is a growing field gathering certainty of purpose, and tremendous knowledge of medications. Watching a fish being anaesthetised by adding the appropriate type and concentration of medication to water is fascinating – well, I suppose to some of us!
Despite the advancements in the field, and an impressive worldwide usage of anaesthesia, there are some times when the response is unpredictable. As much as we know of the biology, biochemistry and physiology of our animals, we sometimes get hit from left field (apologies for the baseball term). It is important to keep in mind that there remains a small number of animals who have unpredictable responses under anaesthesia, and an even smaller number who die despite our best efforts.
The things which allow nature to be so fluid and shapeshifting, are the very same things that might set up for adverse reaction. Two major ways the veterinary team counters is with information, and monitoring. Information comes from a huge group of researchers and veterinary experts and is parlayed through formal education, continuing education and networking with other veterinarians. Monitoring is learned through formal education and during hands on, continuous experience.
Anaesthesia allows a surgical or other procedure to occur in an unconscious animal who has no perception of pain or discomfort, has no memory of pain, and wakes up under pain control as needed (because once consciousness returns so do all the perceptions). They should wake up as if nothing happened – well, maybe just feeling a bit tired.
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■ JO OLVER