What Really Happens When Your Pet Goes Under Anaesthesia

If you’ve ever watched a movie scene where a character drifts off to sleep as a mask lowers over their face, you might imagine that’s what happens when pets are given anaesthesia too.

Understandably, many pet parents feel anxious when their furry family member needs a procedure. The idea of them being “put under” can sound mysterious, even a little scary.

As veterinarians, we believe in lifting the curtain. Our goal is to explain what really happens during anaesthesia so you know your pet is safe, cared for, and closely monitored every step of the way. Here are answers to the most common questions we hear in the clinic.

Not exactly. Most pets start with a carefully chosen sedative “cocktail” - a small injection under the skin, into a muscle, or through a vein. This helps them relax, become drowsy, and drift into a calm state.

Once they are settled, we give an intravenous anaesthetic drug that gently brings them into unconsciousness. At this point, we can place a breathing tube into their airway. This tube keeps their airway protected and allows us to provide oxygen - and, if required, anaesthetic gas - safely and effectively.

It may look simple in the movies, but in reality most awake cats and dogs would not tolerate the strong smell of anaesthetic gas. Trying to force it can cause unnecessary stress or even struggling - something we always want to avoid.

Instead, we sometimes use a mask briefly to deliver 100% oxygen before anaesthesia begins. This ensures your pet’s oxygen levels are stable before we move to the next stage. But the actual process of going under is smoother and safer with injectable medications first.

Once your pet is asleep and their breathing tube is in place, we have two main options to maintain anaesthesia:

• Anaesthetic gas with oxygen: A small, carefully controlled amount flows through the tube to keep them comfortably asleep.

• Intravenous infusion: For some surgeries, we use a slow drip of anaesthetic medication directly into the vein. This allows us to fine-tune the depth of anaesthesia and can result in a quicker recovery.

Whichever method we choose, the dose is always tailored to your pet’s size, health, and procedure.

Safety is always the top priority. Throughout anaesthesia, a dedicated veterinary nurse stays right by your pet’s side, monitoring them from start to finish. We use specialised equipment to track vital signs such as:

• Heart rate and rhythm
• Breathing and oxygen levels
• Blood pressure
• Body temperature

This constant monitoring means we can respond quickly to even small changes. Your pet is never left unattended.

Before any anaesthetic, we also recommend pre-anaesthetic blood tests, which give us important information about organ function and help us plan the safest approach.

When the procedure is finished, the anaesthetic gas or infusion is stopped. Your pet remains under close observation as they gently wake up. Most pets are sleepy but comfortable, and we continue to monitor them until they can swallow and lift their head.

In the hours after, we keep them warm, check their pain relief, and make sure they are calm and settled. Once we’re confident they’re recovering well, we’ll send them home with clear instructions on what to expect and how to care for them overnight.

No two anaesthetic plans are ever the same. We take into account your pet’s age, breed, health status, and the type of procedure. For older pets or those with health conditions, we may adapt our approach, using different drugs, lighter doses, or extra monitoring support.

We understand how much trust it takes to hand your pet over for surgery or a procedure. That’s why our team is always happy to answer your questions, explain our process, and make sure you feel reassured.

While anaesthesia can sound daunting, modern veterinary medicine makes it a safe and carefully monitored process. If you have questions about your pet’s upcoming procedure, our team is always happy to talk you through the details and give you peace of mind.