Can Cats Be Allergic to Anesthesia Drugs?

Anesthetics are drugs used to block the feeling of pain. Anesthetics have two types: local and general. As the name implies, a local anesthetic targets a specific part of the body, leaving the area insensitive to pain. A local anesthetic is used for surgery on the surface of the body; it's injected around regional nerves for a numbing sensation. If Fluffy needs a few stitches, she'll likely be given a local anesthetic to numb the affected area. A general anesthetic causes complete unconsciousness, blocks painful sensations and allows the entire body to relax. When cats are spayed or neutered, they are put to sleep with a general anesthetic for the duration of the surgery.

General anesthetics are typically administered to cats through injection or gas inhalation. Ketamine and xylazine are two of the common injectable anesthetics, often used together for a short procedure. If Fluffy is getting an injectable anesthetic, the dose will be based on her weight. If she's getting inhaled gas, given through a tube in her trachea, it will likely be halothane, sevoflurane or isoflurane. If Fluffy receives gas anesthesia, it will be combined with oxygen and administered according to her breathing, controlled throughout the surgery.

All of the drugs used for anesthetic purposes carry the risk of an allergic reaction. In fact, allergic reaction is the most common complication in the use of local anesthetics, which tend to have few adverse reactions.

Aside from allergic reactions, there are other risks to using anesthetics, and general anesthetics carry greater risk than local anesthetics. Complications occurring under general anesthesia include a slow heart rate, lack of breathing, low blood pressure and sometimes cardiac arrest. Pet Health Network reports that one in every 100,000 animals will have a reaction of some sort to an anesthetic agent. This includes mild reactions, such as swelling at the injection site, to severe reactions, such as anaphylactic shock. Pet MD notes the risk of a healthy dog or cat dying from anesthesia-related complications is one in 2,000. If Fluffy has surgery, a more likely complication is vomiting when going to sleep or coming out of the anesthetic.

Ketamine, a cost-effective choice, can have cardiac effects, so it's often limited to use on younger cats. If a cat experiences a complication under ketamine, the vet has to maintain supportive care until the drug wears off -- once it's in Fluffy's system, it can't be reversed until it runs its course. If there is a complication using inhaled gas, it is much easier to wake up the cat. Inhaled gases are usually more expensive than ketamine, but they're often preferred for older cats because it's easier to control the administration of the drug.

If your vet is recommending surgery for Fluffy, she'll likely come through with flying colors. Although there's no way to know if she has an allergy to the anesthetic until she takes it, the chance of any complications during her surgery can be reduced. The easiest thing to do is ensure that she doesn't eat or drink several hours before she is given anesthesia. Fasting reduces the risk that Fluffy will vomit or aspirate food into her lungs. Your vet may also recommend a presurgical exam and some diagnostic tests to look for any underlying conditions that may put your cat at risk during the surgery. Understanding Fluffy's medical history, lifestyle and current condition allows the vet to choose an appropriate anesthesia and monitor her condition during the procedure.