Albany Blog

Your pet is having a general anaesthetic – what can you expect?

By April 18, 2024April 19th, 2024No Comments

This blog relates to anaesthesia in cats and dogs.


Understandably, your pet undergoing an anaesthetic can be an anxious time. Aiming to be informative and to provide reassurance, in this blog we give step by step insight into what happens when your pet is anaesthetised.

Following comprehensive clinical assessment and preparation (see previous blog), anaesthesia is commenced. The first step is pre-medication. 

Aims of pre-medication

Calms the patient prior to administering injectable anaesthetic

Reduces stress

Reduces the dose of anaesthetic drug required

Provides analgesia (pain-relief)

Smooths recovery

1. The nurse administers, as prescribed by the veterinary surgeon, a combination of sedative and analgesic (pain-relieving) drugs, via injection into muscle.

2. Once the desirable level of sedation is achieved, the nurse shaves fur from the fore limb (this step will have previously been carried out if the patient has had pre-anaesthetic blood testing) and applies a solution to numb the area; the area is then cleaned and an intravenous catheter is placed into a vein. Connectors can be added to this catheter to administer intravenous fluids, if required. A dressing and surgical tape are used to secure the catheter and prevent the patient from removing it.

3. The patient is placed on a table in the clinical preparation area, the veterinary surgeon then flushes the catheter with water for injection to check it is still in place and functioning well, then injects the anaesthetic drug into the vein via the catheter. This drug takes immediate effect.



  1. The patient is then intubated – via the mouth, the veterinary surgeon places an appropriately sized tube into the trachea (windpipe). The tube is checked to ensure that when the patient breathes out, breath can be detected coming from the tube. The tube is then secured in place with bandage and inflated to the correct fit. This ensures the maintenance of appropriate anaesthesia and avoids leakage of anaesthetic gases around the tube.

For cats, prior to intubation, the throat is sprayed with a local anaesthetic. This is to prevent laryngeal spasm – an emergency where the patient is unable to open the larynx (the area that connects the throat to the windpipe) and breathe.

  1. The tube is then attached to the anaesthetic machine which delivers oxygen and anaesthetic gas to the patient. The flow of the gases is calculated, set and continually monitored for each patient and is adjusted as necessary. The required flow will depend on the patient and the procedure, for example a patient having abdominal surgery will require a deeper level of anaesthesia than a patient anaesthetised for x-rays.



  1. The patient and depth of anaesthesia is continually monitored throughout the procedure by the veterinary nurse, observing:

heart rate

respiratory (breathing) rate

reflexes of the patient

mucous membrane colour (the colour of the patient’s gums)


and by our multiparameter machine measuring:

blood pressure

percentage of oxygen in the blood

carbon dioxide output

body temperature


Anaesthetised animals are unable to regulate their own body temperature, so they are carefully kept at a safe, comfortable temperature using blankets, socks and heat pads.


7. Any necessary antibiotics, or further pain relief will be administered via the intravenous catheter prior to removing the patient from under anaesthesia.


Brachycephalic breeds (those with short snouts and flat faces) can be more complicated to anaesthetise and require more intervention due to their narrowed airways; for example, they are given medication to reduce the risk of stomach contents moving back up into the oesophagus – the tube that connects the throat to the stomach.


Removing anaesthesia

8.  The anaesthetic gas is turned off, the cuff on the tube is deflated and the bandage securing the tube is untied, ready for removal of the tube (extubation).

The nurse observes the patient for signs of awareness;

in dogs, these are:

tongue movement

increase in jaw tone – following opening the patient’s mouth, any observed closing or resistance to opening indicates a lessening of muscle relaxation

change in respiratory and heart rate

blink reflex


The tube is gently removed once the patient has regained the ability to swallow.


in cats we look for:

ear twitch

increase in jaw tone

blink reflex


The tube is gently removed before the patient has regained the ability to swallow, to avoid spasm.


In recovery

9. The patient is kept warm; heart and respiratory rates are measured, and level of mobility is observed. Once the patient has managed to sit up and is alert enough, food and water is offered.

10. The patient’s age, health condition, the procedure carried out and the length and depth of the anaesthetic will all have a bearing on recovery time. Once satisfied that the patient is stable enough, the nurses will arrange discharge.


At home

Anaesthetic drugs can take around 24 hours to leave the body. Once home your pet should not be left alone in the immediate period following discharge. You will be asked to keep your pet warm and quiet and to feed a light diet to avoid diarrhoea post-anaesthetic. Sometimes the tube placed down the windpipe can cause a tickly cough or loss of voice for a few days. You will be asked to contact the practice the following morning to let us know how your pet is recovering.