The method of general anesthesia is determined by the health of the animal, the procedure, and the experience of the surgeon/anesthetists. Within each method is a whole sweep of different options depending on which anesthetic drugs are chosen. The basic protocols are:
- Induction and maintenance with injectable agents
- Induction with injectables, maintenance with anesthetic gas
- Induction and maintenance with anesthetic gas
Of these, option #2 is the most widely used.
In preparation for a general anesthetic, the patient (over 4 months of age) must not eat for at least 10 to 12 hours before hand so their stomach is empty. This is to prevent vomiting under anesthesia and the risk of inhaling food down into the lungs.
Every dog undergoing anesthesia is carefully assessed with a physical exam and possibly blood work. This is to identify factors which need correction ahead of the anesthesia for maximum safety.
Once the patient is stable, a premedication injection is given. This provides pain relief, minimizes the amount of inducing agent required, and makes for smoother maintenance.
A catheter is placed in the foreleg and once the premed has taken effect, an induction agent is slowly injected into the bloodstream via the catheter, until the dog is asleep. A tube is then passed into the trachea (windpipe) and connected to a anesthetic machine. The dog is maintained under anesthesia by adjusting the gas flow and levels of anesthetic agent.
Once the procedure is completed, the anesthetic gas is turned off, the system flushed with oxygen, and the patient monitored while they regain consciousness.