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© WILLOWS VETERINARY CENTRE AND REFERRAL SERVICE
Willows Information Sheets www.willows.uk.netT: 0121 712 7070
General anaesthesia
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 when your pet will be ‘asleep’ under the anaesthetic. 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 different from
the unconsciousness than occurs in injury or disease.
What do I need to do to prepare my pet for surgery?
• You will need to fast (starve) 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 in the morning!
• Take your dog for a walk in the morning to allow him or her
to empty the bladder and bowels.
• Watch out for any signs of illness not related to the
procedure which is about to be carried out on your pet, 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 (a ‘pre-med’).
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 through this endotracheal tube.
How do you keep my pet safe during general anaesthesia?
Our aim is to provide the best care for your pet at all times,
including during general anaesthesia. To this end, Willows is
fortunate to have a team of dedicated anaesthetists, including two
recognised, accredited anaesthesia Specialists, who are on hand to
supervise and assist with each anaesthetic procedure, as required.
For the whole duration of general anaesthesia, your pet will be connected
to an anaesthetic machine, which delivers a mixture of anaesthetic gas
and oxygen. The amount of gases and the type of anaesthetic circuit used
is adjusted to the needs of each individual patient.
While your pet is anaesthetised, he or she will be closely observed
throughout the procedure by veterinary anaesthesia staff and/or
highly trained, qualified nursing dedicated to the one-to-one care
of your pet. In addition, specialised monitoring equipment is used
to keep a close watch on your pet’s progress. The monitoring
equipment used depends on the surgical procedure, type of
anaesthesia used, and medical history of each patient.
At Willows, we use monitoring equipment which measures:
• heart rate and rhythm (electrocardiography or ECG)
• pulse rate
• respiratory rate
• body temperature
• blood pressure
• oxygenation of blood (called pulse oximetry)
• carbon dioxide level in the breath (called capnography).
The staff involved will also monitor your pet’s pulses, gum (mucous
membrane) colour, position of the eye and reflex activity to determine
the depth of anaesthesia. All the readings obtained and any observations
are recorded every 5 minutes on an anaesthetic record chart.
When the surgical procedure is complicated or for a pet with a
higher risk of undergoing anaesthesia, more information about the
patient is required to make sure that he or she remains safe and
comfortable. To obtain this information we use more advanced
monitoring techniques, including:
• ‘invasive’ arterial blood pressure measurement (using a
cannula which is placed in an artery to directly measure
the arterial blood pressure, rather than using a cuff)
• central venous pressure monitoring (measuring the blood
pressure in the veins deep inside the body)
• measuring the level of muscle relaxation (called
neuromuscular blockade)
• measuring of breath (spirometry)
All this information is important, and it helps us to anticipate
potentially significant problems almost before they occur. If there
are any concerns, an anaesthetist can take the necessary actions to
bring all the parameters back to the normal levels as promptly as
possible. The adjustments required under such circumstances may
include giving additional injections, more pain relief, supplementary
intravenous fluids or oxygen. If there is any problem with the
breathing, your pet will be connected to a unit which automatically
inflates the chest (mechanical ventilation) to make sure enough
oxygen is provided.
We will take special care to make sure your pet is warm during
whole procedure and on recovery. Under general anaesthesia, the
brain does not control body temperature and patients can lose heat
very quickly. It is especially important to maintain body temperature
in small, young and short-haired animals. We use a range of
© WILLOWS VETERINARY CENTRE AND REFERRAL SERVICE
Willows Information Sheets www.willows.uk.netT: 0121 712 7070
warming devices to prevent heat loss – in the operating theatre our
patients are placed on special heated beds with in-built sensors, and
intravenous fluids are heated by fluid warmers.
When a procedure has finished, the anaesthetic gas is switched off
and the patient is given oxygen until he or she starts to recover and
wake up. Most pets recover consciousness very quickly, although
older animals or those who have had a longer anaesthetic may
recover more slowly.
During recovery, your pet will be taken to a warm and comfortable
bed in the kennels (or our Intensive Care Unit if required) and will be
carefully monitored until he or she is fully awake.
How is my pet prevented from feeling pain?
Most of our 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.
For more information about pain and its management, see our
information sheet ‘Pain – an overview’.
What will my pet be like after coming home from Willows?
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 after a general anaesthetic?
• 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.
Why should I bring my pet to Willows for a procedure under general anaesthesia?
Our anaesthesia and analgesia department is led by highly
experienced recognised, accredited Specialists who aim to provide
the safest possible sedation, anaesthesia and pain management
for your pet. Our anaesthesia/analgesia team works alongside the
other Specialists at Willows who are highly trained in a wide variety
of different disciplines. They oversee all the general anaesthetic
procedures which are carried out at Willows, in addition to
supervising sedation and pain management regimes tailored to each
patient’s needs. They liaise closely with our 24-hour veterinary and
nursing staff, all of whom help not only to give our patients the best
possible outcome, but also to ensure that they remain comfortable
at all times, whatever their problems may be.
If you have any concerns at any stage after your pet’s operation,
please do not hesitate to contact us.
© WILLOWS VETERINARY CENTRE AND REFERRAL SERVICE
Willows Information Sheets www.willows.uk.netT: 0121 712 7070
Specialist Referral Service
www.willows.uk.net
The information contained is proprietary to Willows Veterinary Centre
& Referral Service and may not be modified, reproduced, distributed
or utilised in any manner in whole or in part, without the express prior
written permission of Willows Veterinary Centre & Referral Service.