Albany Blog

Preparing for your pet’s general anaesthetic

By April 19, 2024No Comments

This blog relates to anaesthesia in cats and dogs.


General anaesthesia provides a reversible means of keeping a patient perfectly still whilst preventing awareness of, and response to, pain. It is used for a wide variety of procedures, from suturing wounds and cleaning ears through to large orthopaedic and abdominal surgeries. Due to the potentially uncooperative nature of veterinary patients, and to ensure that strict radiation safety legislation is complied with, sedation or anaesthesia is often required for procedures that are not considered painful, for example x-rays or other diagnostic and investigative procedures.


A combination of drugs and methods are used to achieve anaesthesia:

 1. Pre-medication with a sedative and pain relieving (analgesic) drug given via injection into muscle.

2.  Anaesthetic drug injected into a vein in the leg.

3.  Maintenance of anaesthesia using an inhalant drug (drawn in by breathing), usually delivered via a tube placed down the trachea (windpipe).


The choice of pre-medication and anaesthetic drugs are tailored to each individual patient, depending on factors including age, weight, existing health conditions and the procedure for which the anaesthetic is required.

You may wonder why we don’t just use a sedative or local anaesthetic for some procedures – the answer to this is that we have much greater control during a general anaesthetic; continual monitoring allows us to respond to any fluctuations in the patient’s consciousness and adapt the level of anaesthetic accordingly. We use a carefully calculated combination of drugs in our aim for a smooth transition in to, maintenance of and transition out of, anaesthesia.


Preparing for an anaesthetic



The gathering of clinical history relating to

current health

current medications

any recent changes in thirst or appetite

any change in bodyweight

 previous anaesthetic history

temperament of the patient

This information will help guide the management of the patient; for example, sometimes we need to alter how regular medications are given leading up to, and around the time of, an anaesthetic. Additional medical support may be required, for example if we are concerned about potential blood clotting issues. Sometimes extra support in terms of intravenous fluids may be necessary to correct dehydration, support the volume of blood in the patient’s circulatory system and to restore electrolyte balance, helping to maintain fluid balance and support muscle and nerve function.

A clinical examination, paying particular attention to

the central nervous system – checking brain and spinal cord health.

the cardiovascular system – checking the health of the heart.

the respiratory system – checking for any potential abnormalities with the function of the lungs.

Blood screening

Blood testing allows the evaluation of internal organs and blood cells. The tests recommended will vary according to the patient’s age and general health; analysing blood chemistry will give us an insight into the health of the liver and kidneys (two organs responsible for processing the anaesthetic drugs) and indicate any areas of potential concern. Haematology analyses the health of the blood, screening for signs of anaemia (low red blood cells), inflammation, infection and inability to fight it, stress, leukaemia, bleeding problems and hydration status.

Potential issues discovered during examination or blood testing are then considered when planning the safest possible anaesthetic. In some cases, issues detected at this stage may change treatment decisions, possibly even resulting in the decision not to proceed with a general anaesthetic if the risk is considered too great for the patient.


Obtaining owner consent

Although rare, adverse reactions to general anaesthetic are a risk. The consent form records the owner’s (or someone acting on their behalf) agreement to proceed with an anaesthetic and accompanying procedure. Before being asked to sign, you should be able to understand and retain the information provided and be given the opportunity to ask questions.


Prior to admission for an anaesthetic, you will be asked to starve your pet. You will be advised for how long, depending on the age of the patient (puppies and kittens need a much shorter starvation period to avoid complications). During anaesthetic, the body’s reflexes are temporarily disrupted. If the patient’s stomach has food in it, there is a risk of vomiting and then the food getting into the lungs causing damage and affecting breathing. In order to prevent dehydration, water should not be withdrawn at home.


Where possible, dogs should be walked prior to anaesthetic to give them opportunity to empty their bladder and bowels. Cats should be provided with a litter tray.


Your pet’s weight will be recorded and this will be used to calculate anaesthetic drug doses.