Pet Owner’s Guide To Anaesthesia and Anaesthetics - Church Walk Vets

Pet Owner’s Guide To Anaesthesia

Written by Helen Summers Saturday, 05 February 2011 11:36

Anaesthesia (also referred to as ‘general anaesthesia’) is by definition ‘a state of unconsciousness produced by anaesthetic agents, with the absence of pain sensation over the entire body and a greater or lesser degree of muscle relaxation’.

Anaesthesia is used in veterinary practices every day to perform surgery, diagnostic tests and procedures which would be impossible to undertake on a conscious animal. Procedures include routine surgery such as neutering, planned procedures such as dentistry, x-rays and emergency surgery such as foreign body removal, fracture repair, or emergency splenectomy.

Preparing Your Pet for Anaesthesia

If your vet has recommended that your pet needs to be given an anaesthetic, you will be asked to withhold food on the evening prior to the procedure. Our usual policy is to withhold food after 8pm on the evening before surgery, although individual requirements may vary. Your pet can still have access to water overnight. Withholding food is necessary to help prevent vomiting during the anaesthetic as this can cause the animal to inhale food particles, which could block the airway or cause infection in the lungs. Small pets such as rabbits, guinea pigs and hamsters do not need to be fasted as they are unable to vomit, so do not have the associated risks. If your pet is on medication you should check with your veterinary surgeon as to when it should be given.

On the Day of the Anaesthetic

Your pet will be admitted to the surgery by one of our qualified veterinary nurses or veterinary surgeons. We will check the necessary details and go through the consent form with you, which you will then need to sign. If you have any questions or concerns about the anaesthetic or the procedure the vet or nurse will be able to answer them for you. Your pet is then weighed (to ensure drugs are dosed accurately) and then placed in a kennel to settle.

Pre–anaesthetic Blood Testing

We recommend pre-anaesthetic blood testing in older patients (typically over 7 years of age), or for those with any known or suspected health problems. The test results give our vets a picture of the animal’s general health status and ability to tolerate a general anaesthetic. If the test results are normal then we can proceed with confidence and the knowledge that any risks associated with anaesthesia are kept to a minimum. However, if the results are not within the normal ranges, we can alter the anaesthetic procedure or take other precautions to reduce the risk of possible complications. This may involve putting the animal on a drip to correct dehydration and help support the organs during the anaesthetic. If your pet’s results are abnormal the vet will contact you to discuss this before continuing with the anaesthetic. Our routine pre-anaesthetic blood test includes the following (though other tests may also be performed if deemed necessary):

• Liver and kidney function - As the drugs used in anaesthesia are processed and excreted by the liver and kidneys it is important to check they are functioning properly before an anaesthetic is given.
• Blood glucose - Blood glucose is tested to check for diabetes. Low blood glucose can also indicate liver disease or infection.
• Total protein - Protein levels are checked as abnormalities can indicate liver, kidney, or intestinal disease.
• Haematology - A complete blood cell count including red and white blood cells and platelets is performed to detect any conditions which may cause complications if surgery is performed. A red blood cell count will detect anaemia and a white blood cell count can indicate stress, leukaemia, inflammation or inability to fight infection. A low platelet count can indicate a problem with blood clotting.
• Electrolytes (Sodium, potassium and chloride) - It is important to check electrolyte balance as abnormal levels can be life threatening. Imbalances in electrolytes can be caused by vomiting, diarrhoea, dehydration, heart problems and endocrine system disorders.

Most anaesthetic procedures consist of four stages; pre-medication, induction, maintenance and recovery. The procedures and drugs used can vary depending on the size, species, age and health of the patient and the procedure being performed. Some procedures may be performed without the pre-medication phase.

Health Check and Pre-medication

If test results are satisfactory the next step is to give the animal a pre-medication injection. One of our vets will check your pet over and give an injection to lightly sedate him/her and reduce anxiety. This means your pet will be more relaxed when given the general anaesthetic which makes induction smoother and also means that the anaesthetic drug can be given in a smaller quantity.

Induction of Anaesthesia

Your pet will be given an anaesthetic agent, usually into the cephalic vein of the front leg, to induce anaesthesia. Once they are anaesthetised, or ‘asleep’, they pass into the maintenance phase.

Maintenance of Anaesthesia

Once the patient has been induced, anaesthesia needs to be maintained to keep them asleep throughout the procedure. This is most commonly done by placing a tube into the windpipe which connects to an anaesthetic machine. The machine delivers a mixture of oxygen, anaesthetic gas and vaporised anaesthetic drugs directly to the patient.

Monitoring

Throughout the procedure your pet is continually monitored by a qualified veterinary nurse with the assistance of an anaesthetic monitoring machine. This measures heart rate, ECG, respiratory rate, blood oxygen levels, blood pressure and body temperature. A veterinary surgeon is also present at all times.

Recovery

When the procedure has finished, the anaesthetic gas and vapour is switched off and the patient is given oxygen until they start to recover and wake up. Due to the use of short-acting anaesthetic drugs the animal will usually recover very soon, although older pets or those who have had a longer anaesthetic may recover more slowly. Your pet is taken to a warm and comfortable bed in the kennels and monitored carefully until fully awake. Most pets will be fit to go home the same evening, although some, such as those which have had long or complicated surgery, may be required to stay in longer for further monitoring.

Collection

When you collect your pet you will be given a post-anaesthetic care sheet to help you continue your pet’s recovery at home. One of our veterinary nurses or veterinary surgeons will go through this with you and answer any questions you may have before discharging your pet. In some cases you may also need to make an appointment for a check-up with one of our vets.

Safety of Veterinary Anaesthetics

All anaesthetic procedures carry a small risk, although the risk is especially low in healthy animals. To help minimise the risk one of our vets will examine your pet before giving any anaesthetic and will recommend any tests if necessary. Your pet will be closely monitored by qualified and experienced veterinary surgeons and nurses throughout the anaesthetic and during recovery. We appreciate it can be worrying leaving your pet with us for an anaesthetic so please don’t hesitate to contact us if you wish to discuss any aspect of the procedure and we can hopefully help to put your mind at rest.