Monday, August 16, 2010

Veterinary fact of the day: premedication

Welcome to a new feature: the veterinary fact of the day. See the bottom of this post for more information.

Today’s veterinary fact is a brief overview of pre-medication, or premed. (This is different from a premed student.)

What’s pre-medication?
It sounds like a very general term! But in a veterinary hospital, you “premed” an animal before general anesthesia.

What’s in a premed?
Premeds are tailored to the particular animal, based on age, species/breed, temperament, pre-existing conditions, etc. Generally, a premed will include an analgesic, a sedative or tranquilizer, and sometimes an anticholinergic.

Why would you give an animal an anticholinergic in their premed? Also, what the hell is an anticholinergic?
An anticholinergic is a medication which competes with a specific kind of neurotransmitter, part of the parasympathetic nervous system. When your brain sends out messages to your body saying “time to relax, to rest and digest,” the anticholinergic blocks those messages. This makes the body do the opposite of rest and digest (increase heart rate, for example). Why would you give one of those when you are about to make the animal lose consciousness? It helps keep the heart going at the rate you want, even when the rest of the animal’s body is being artificially put into what you can think of as close to the “off” state. Also, it makes the patient make less saliva. Apparently that can be important in ruminants (cattle!). I can only imagine.

Why would you give an animal a tranquilizer or sedative in their premed?
Well, first, what is the difference between a tranquilizer and a sedative? They are really two parts to the same equation; a tranquilizer makes you feel calmer, and a sedative makes you act calmer. Why give them? To make things easier on the animal, who is in a scary situation. To make things easier on the anesthetist, who is handling an animal that might be scared.

Why would you give an animal an analgesic in their premed?
Why a pain reliever? They aren’t going to be feeling anything while they are under general anesthesia, but they will certainly be feeling something when they wake up, unless they have an analgesic on board. Also, putting in an intravenous catheter (for the general anesthesia) can be painful.

Why are you telling me all this?
I just went back to veterinary classes after a year of research. I don’t expect to have much time to blog in detail, but I figured a quick report daily (if possible; I expect to slip to every several days at least) from the trenches of the third year of vet school might be interesting. I will call it the “veterinary fact of the day.” This is the year in which we learn how to fix what’s broken. I would love feedback — let me know if I am covering things that are interesting, and if you have any requests.

What did you do today?
Two hours of Anesthesia and Analgesia lecture. Two hours of Large Animal Medicine and Surgery lecture. Lunch! (Food and statistics; I am still editing my thesis.) Two hours of Small Animal Medicine and Surgery lecture. Home!


  1. Very interesting. Good for a pet owner to know as animals tend to be anesthetized more than humans (for example, for things like teeth cleaning).

  2. Glad you enjoyed it. Anesthesia is definitely more complicated than it can appear. Hopefully I’ll be covering more of it on this blog as the class goes on.

  3. What can you say about accidentally mixing a bit of dexdomitor into bottle of torbugesic? I was trying to draw up some torbugesic using a syringe with dexdomitor in it but the bottle sort of suck in a bit of the dexdomitor. That bottle is already contaminated so it can be used anymore or we can just use it for Dexdom-Torb combo? We can't use the Torb for our Butorphanol-Acepromazine-Atropine combo?

  4. You should definitely ask a real vet that question. I am just a student!