Anesthesia really freaks out some owners - especially when they have very old animals.
Note: age is not a disease. If somebody tells you your pet is "too old" to have anesthesia, they are pulling your leg.
Animals of any age can undergo anesthesia safely, as long as they are healthy, the proper anesthesia is used and they are monitored closely.
Consider this: aside from spay and neuter surgeries, two of the most common reasons anesthesia will be used on a pet is to remove a bothersome lump or to do a dental procedure.
Who do you think has the most tumors and dental problems? You got it - older pets.
So it should be slightly more comforting to know that veterinarians acutally are used to anesthetizing older patients, and the vast majority of these animals do very well during and afterward.
There are two general forms of anesthesia used on animals: injectable anesthetics and gas anesthetics. Most of the time, a combination is used. First, an injection of a tranquilizer-anesthetic cocktail is given, followed by intubation (placing a breathing tube into the trachea) and the delivery of oxygen and gas anesthesia to the patient to maintain a steady-state of sleep.
It is a special sleep, since it prevents the body from feeling pain as well as keeping it immobilized.
Anesthetics wear off after a given time, as the patient's lungs, liver and-or kidneys clear them from the bloodstream. The mode of the body's clearing the anesthetic will vary with the drug. Some patients are very efficient at this, some are not.
Animals with current problems can be overdosed with medications given at the normal dosages, so if your pet is sick or acting differently, it is best to bring this up BEFORE anesthetics or tranquilizers are given.
A few injectable anesthetics or tranquilizers are reversible.
Patients given these drugs can be given a second drug when the effects of anesthesia are no longer needed, and the animal will awaken (usually) quickly, with (usually) few side effects. Notice my hedging? I have to hedge, because every animal is different.
Also, an individual pet may have varied responses to the same doses of the same tranquilizers on different days, depending on its state of excitement.
How do veterinarians decide how much to give?
We use guidelines published in reference manuals, recommendations from the drug manufacturer, experience and a dash of common sense.
Protocols for anesthesia and pain management go in and out of favor within the profession, sometimes from one year to the next. There are often heated arguments among veterinarians over which cocktail works best in which situation.
What's more, there often are new drugs being thrown into the mix by manufacturers.
Anesthesia is certainly not without risks, heck, before I received it for an outpatient procedure, I was urged to have a living will prepared.
Talk about freaking out - it was more than a little unsettling.
But anesthesia-related deaths are rare in both people and animals, since the protocols used are constantly improving. Fluids are often administered through an intravenous catheter to help maintain normal blood pressures and hydration during anesthesia.
Monitoring anesthetized animals is much like that in people nowadays, making use of some pretty nifty machines, so the person delivering anesthesia can intervene early, should problems arise.
Still worried about your pet's upcoming anesthesia?
Screening blood and heart tests (some identical to those done on people) are available for any age pet to evaluate that animal's overall health before anesthesia is administered.
Animals older than 7 years should always have these tests performed, since they are more prone to certain organ diseases that can make anesthesia more dangerous for them. Again, just because an animal is old, does not mean it does have a problem - that is the reason for the tests.
We screen many patients, young and old, and find unexpected problems much less commonly than we find the animals to be in good health. Among those cases with abnormal test results, even fewer require us to postpone or cancel the planned procedure, but it does happen.
Many of these problem patients can have the anesthetic procedure at a later time, once the problem found has been addressed, treated, and is either resolved or under control.
Some animals don't much appreciate our well-intentioned screening tests (case in point, my cats, Wyatt and Virgil) and require anesthesia FIRST, sort-of negating the pre-anesthetic benefit. My take on that is that blood tests are never a bad idea, and if anesthesia is required to get it, do it anyway.
It may be the only chance to get a serious look at that animal, and provides a good baseline for future reference. If it's good enough for valuable and sometimes rare zoo animals, it's good enough for my two tiger wanna-bees.
Nobody would expect a zoo vet to sidle up to an angry rhinoceros and charm him out of a little blood sample without a carfentanil cocktail on-board (received lovingly through a dart shot from a CO2 rifle.) My guys got to go sleepy-bye after a similar poke in the thigh, no darts needed, just a technician with super-human strength to hold them still. No, not simultaneously - I prefer to do my surgeries one at a time. Anesthesia and surgery (neuter/declaw) went well for my feisty cats, a distant memory, now that they are mature adults - and since they still can't remember how to avoid being stepped on in our home, I assume they don't remember a thing.
Daverio is a veterinarian at Williamsport West Veterinary Hospital.