Levels of Anaesthesia – Understanding the Planes of Anaesthesia in Your Pet

When your pet undergoes anaesthesia for surgery or a medical procedure, their safety is our top priority. Anaesthesia isn’t simply a case of "awake" or "asleep"—it occurs in different levels, known as planes of anaesthesia, which need to be carefully monitored and adjusted to ensure your pet remains stable throughout the procedure.

At Oakleigh Central Vet, a dedicated nurse continuously monitors your pet’s vital signs, including heart rate, respiratory rate, blood pressure and temperature, from the moment anaesthesia begins until they are fully awake. Here’s what happens during anaesthesia and how we ensure your pet’s safety every step of the way.

The Four Planes of Anaesthesia

Anaesthesia progresses through different stages, and the goal is to maintain your pet at the optimal level—deep enough to prevent movement and pain, but not so deep that it suppresses essential functions.

• Stage 1: Induction – This is the transition from wakefulness to unconsciousness. Your pet may feel slightly disoriented as the anaesthetic takes effect, but this stage is brief and controlled.

• Stage 2: Excitement Stage – Some pets may exhibit involuntary movements, vocalisation, or irregular breathing as their body fully transitions into anaesthesia. This phase is managed carefully with medications to keep your pet comfortable.

• Stage 3: Surgical Anaesthesia – This is the ideal plane for surgery, where pets are fully unconscious, and their muscles are relaxed. Within this stage, there are different depths of anaesthesia, depending on the type of procedure. Lighter sedation is used for shorter, less invasive procedures, while deeper anaesthesia is required for more complex surgeries.

• Stage 4: Overdose/Dangerous Anaesthesia – If anaesthesia becomes too deep, it can suppress vital functions such as breathing and heart rate. This is why constant monitoring is crucial—our team ensures that your pet never enters this stage by adjusting anaesthetic depth as needed.

How We Monitor Anaesthesia in Your Pet

Anaesthesia affects the entire body, so continuous monitoring is essential to keep your pet safe. Throughout the procedure, a dedicated veterinary nurse closely tracks your pet’s vital signs to ensure they remain in a safe and stable plane of anaesthesia.

• Heart Rate (HR) – The heart must maintain a steady rhythm to circulate oxygen and nutrients. We use a stethoscope and ECG monitoring to track heart function in real-time.

• Respiratory Rate (RR) – Oxygen is critical during anaesthesia, so we carefully monitor how well your pet is breathing and adjust oxygen delivery if needed.

• Blood Pressure (BP) – Low blood pressure can indicate that anaesthesia is too deep, so we track this closely and provide IV fluids or medication if necessary.

• Body Temperature (Temp) – Pets can lose body heat under anaesthesia, leading to hypothermia. We use warming blankets and heat pads to keep them at a safe temperature.

• Oxygen & Carbon Dioxide Levels – Special monitoring devices measure how well your pet is oxygenating their blood and expelling carbon dioxide, ensuring their breathing remains stable.

Adjusting Anaesthesia for a Safe Procedure

Anaesthesia isn’t "one size fits all"—it’s tailored to each pet based on their age, breed, health status and the type of procedure. Our veterinary team continuously adjusts the depth of anaesthesia as needed, ensuring your pet stays comfortable without excessive sedation.

We also incorporate pain relief medications before, during and after the procedure, so your pet wakes up as comfortably as possible.

Continuous Monitoring Through Recovery

Monitoring doesn’t stop once surgery is over. As your pet begins to wake up, we carefully oversee their transition back to consciousness, ensuring they wake up slowly, calmly and comfortably.

• Pain Management – If needed, additional pain relief is provided to keep your pet comfortable.

• Temperature Control – We continue using warming blankets to prevent chills.

• Observation for Complications – Our team closely watches for any signs of discomfort, nausea or delayed recovery.

  
  

To help your pet feel even more at ease, we also use pheromone plug-ins in our dog and cat recovery wards. These natural calming scents help reduce stress, creating a relaxing environment for their wake-up phase.

Final Thoughts

Anaesthesia is a vital part of veterinary medicine, and when done properly, it is safe, carefully controlled and continuously monitored. Our veterinary team takes every precaution to ensure your pet is comfortable, stable and well-cared-for throughout their procedure.

If you have any concerns or questions about your pet’s upcoming anaesthetic, don’t hesitate to ask. We’re here to guide you through the process and provide peace of mind knowing your pet is in expert hands.