Anaesthesia Basics

Why does my pet need to be anaesthetised?

Many of the procedures we need to carry out cannot be performed on a conscious or sedated patient because they will not be relaxed enough. Unlike humans we cannot ask our patients to place themselves in specific positions required for X-rays, scanning or surgery. Although we can use local anaesthetics to numb a surgical site, administering the local anaesthetic in itself may cause discomfort and it does not prevent animals from moving during the surgical procedure.

What is an anaesthetic?

There are several types of anaesthesia, but all of them lead to a loss of sensation. General anaesthesia is a state of reversible unconsciousness. Anaesthetic drugs injected into veins or anaesthetic gases breathed into the lungs are carried in the bloodstream to the brain. These drugs stop the brain recognising messages from nerves in the body. This is a different type of unconsciousness than that which results from injury or disease.

What do I need to do to prepare my pet for surgery?

  • Fasting your pet overnight – your pet should have their normal meal the night before admission (unless otherwise instructed), but should have no further access to food after this. However, he or she should have free access to water until you leave the house to come to the surgery.
  • Cats should be kept in during the night before the procedure to prevent them helping themselves to food from elsewhere and to make it easy to find them!
  • Take your dog for a walk in the morning to allow him or her to empty the bladder and bowels.
  • Monitor your pet for any signs of illness not related to the procedure about to be carried out, and let the vet or nurse know if you have any concerns.
  • Have a note of your pet’s current medication, including over the counter preparations and make sure that the vet or nurse knows about these at the time of admission.

What happens after my pet has been admitted?

The anaesthetic drugs to be used will be chosen according to the procedure that is being performed and the medical history and findings on physical examination of your pet. Your pet will then be injected with pre-anaesthetic medication. After an appropriate amount of time, an intravenous catheter will be placed to allow administration of drugs and fluids during the procedure. For most pets we will then use this catheter to inject an intravenous anaesthetic agent which allows us to place a tube (called an endotracheal tube) down the patient’s wind pipe (trachea). During most of the procedure, further anaesthetic drugs are administered as a gas via this endotracheal tube.

How do you prevent my pet from feeling pain?

Most of the patients undergoing anaesthesia will receive at least two types of painkillers. The most commonly used are the morphine type drugs and drugs from the aspirin family (the so called ‘non-steroidal anti-inflammatory drugs’ or NSAIDs). We also use different techniques and medications taking into consideration your pet’s history and the procedure he or she is having.

What will my pet be like when they come home from the vets?

If your pet is discharged on the day of surgery, he/she will probably be a little sleepy. Strong painkillers will have been given and these will last some time. You should offer your pet some light food (e.g. boiled chicken or fish and rice) and water, but do not expect him or her to have a normal appetite. The effects of the anaesthetic will wear off over the next few days. Please look out for any signs of pain or discomfort and contact the practice if you are at all concerned.

What can I do for my pet?

  • Provide him/her with a bed in a quiet, warm area.
  • Do not let cats go out until the next day, if at all possible, as their balance may not be back to normal.
  • Take your dog out to the garden or for a very short walk to allow him/her to pass urine but do not let him/her off the lead.
  • Follow the instructions provided by your vet for medication and general care which is specific to his/her condition.


If you have any queries, please do not hesitate to contact us.

Arranging a referral for your pet

If you would like to refer your pet to see one of our Specialists please visit our Arranging a Referral page.