Side Effects of Anesthesia in Cats

As a loving cat owner, you naturally hope that your cat never needs surgery or another major procedure, but that won't always be the case. If your cat needs surgery, dental work, or a procedure like an MRI, your vet may need to anesthetize him so that he doesn't feel pain and so that he stays still during the process.

Sleeping kitten - portrait
Anesthesia can cause some side effects for cats.
credit: SocjosensPG/iStock/GettyImages

While anesthesia can cause some side effects in cats, you should familiarize yourself with what those side effects are, how your vet can minimize those side effects, and any risk factors your cat may have. With this information, you can better decide whether or not to proceed with the procedure.

Types of anesthesia

Veterinarians use two types of anesthesia: Injectable and inhalant. Injectable anesthesias are grouped into:

  • Barbituates
  • Dissociative Anesthetics
  • Nonbarbiturate Hypnotics

Propofol, which is a nonbarbituate hypnotic, is often used for feline surgeries, since it quickly takes effect, rarely has side effects, and pets recover quickly after its use. But, because the liver metabolizes Propofol, it shouldn't be used for cats who have liver diseases.

In place of injectable anesthesia, vets can also administer inhalant anesthesia by placing a mask over a cat's nose and mouth, or by inserting a tracheal tube. Many vets opt to use the inhalant anesthesia, Isoflurane. Isoflurane is considered to be a very safe choice. Pets recover from it quickly, and vets may use this anesthesia for pets who have heart problems.

Different types of anesthesia offer different benefits, and some may be better choices for pets who have pre-existing health issues or risk factors. Your vet will consider all of your cat's medical history and current health when determining the best type of anesthesia to use.

Anesthesia risk factors

Any time a cat undergoes any sort of anesthesia, there's the potential risk of a side effect. This is true whether your cat is receiving short-term sedation for a quick procedure or a longer-term anesthesia for a multi-hour surgery. The good news is that anesthesia reactions are very rare, with just 1 in every 100,000 pets (including both cats and dogs) having a reaction.

Anesthesia reactions vary both in their type and severity. A reaction can be as minor as local site swelling, or as serious as anaphylactic shock and death. While the prospect of your cat having a bad reaction to anesthesia is frightening, it's important to remember that these reactions are rare and your vet can take steps to reduce the chance of your cat having a reaction.

Common anesthesia side effects

Some of the most common anesthesia side effects in cats include allergic reactions, which can be localized or system-wide. These reactions can result in swelling in your cat's body which could affect his ability to breathe.

As cats wake up from anesthesia, it's common for them to vomit. Because cats are still regaining control of their bodies, it's possible for them to breathe that food into their lungs, which could cause pneumonia. This is why your vet will likely have you fast your cat before surgery.

Anesthesia can result in organ failure, which can happen both in cats with normal organ function and in cats whose organs were already functioning incorrectly. If a cat's blood pressure drops too low or if the pet gets too cold during surgery, the anesthesia can result in kidney damage, too.

In some cases, a cat with an undiagnosed heart condition can be stressed under anesthesia. This can result in cardiac arrest. Anesthesia can also trigger severe seizures. Remember, though, that serious reactions to anesthesia are rare.

Minimize anesthesia side effects

These side effects are frightening, but proper care before, during, and after surgery can minimize the chance that your cat will experience any of these side effects. Before surgery, your vet will perform bloodwork to assess your cat's kidney and liver function. Your vet will assess these bloodwork results and analyze your cat's overall health to make sure that she's healthy enough for the surgery.

During the surgery, your vet will take and monitor your cat's temperature to ensure she doesn't get too cold. Other monitoring devices will track your cat's blood pressure, heart rate, respiratory rate, and oxygen rate, so your vet can immediately take steps to correct any problems that could arise before they have the chance to cause serious harm. Your vet will place an IV catheter in your cat before surgery and will leave it in place throughout the procedure, which allows the vet to quickly administer any medications your cat might need.

Vets can also administer fluids through an IV catheter during the surgery, which can help to maintain a cat's blood pressure levels. By using the least amount of anesthesia needed to get the desired effect, the vet can minimize the amount of anesthesia that a cat's body needs to process. Often, a veterinary technician will be assigned to monitor the cat constantly throughout the surgery. They will keep an eye on all of the machines and your cat's vital levels so that the surgical team can take immediate action to correct any potential issues.

Cat after anesthesia behavior

As the anesthesia wears off, your cat will probably be groggy and tired. Some cats can have opposite reactions, though, and you may notice your cat restless after anesthesia. If you notice your cat hyperactive after anesthesia, she should be carefully monitored and confined to a safe space to prevent her from hurting herself.

As your cat recovers, she may have a harder time controlling her body temperature, so you may notice she appears to be cold. Some cats appear to be disoriented or uncoordinated. Most of these effects should have worn off by the time that you pick your cat up from the vet.

The types and severity of the side effects that you'll see will depend on the type of anesthesia used, the length of the procedure, and your cat's individual tolerance for the anesthesia.

Safe anesthesia recovery for cats

To help your cat recover safely from anesthesia, follow your vet's directions to a T. Your vet will probably keep your cat for at least a few hours after surgery to observe his recovery. When it's time for your cat to be discharged, your vet or a veterinary technician will provide you with some discharge paperwork and directions on how to care for your cat at home.

In most cases, your vet will recommend that you keep your cat confined to a single room as he recovers. There should be no other pets or animals in the room, since your cat will probably be groggy and slow to react. Leave the cat carrier door open and allow your cat to stay in the carrier as long as he wishes.

Your vet may allow you to give your cat a small meal that evening, but you will need to monitor for any vomiting after your cat eats. The exact care that your cat needs will depend on the surgery that he's had and his individual health issues, so be sure to follow the specific directions that your vet provides. If you have any questions or concerns about your cat's recovery after surgery, contact your vet immediately.