Anesthesia in cats
Anesthesia is a subject that often worries many owners, but many pets will undergo an anaesthetic during their lifetime. It is important to therefore have an understanding of the subject.
What is anesthesia?
Anesthesia is defined as 'insensitivity to pain, especially as artificially induced by the administration of gases or the injection of drugs before surgical operations'.
A general anesthetic is when the patient is placed into a state of unconsciousness. They are not able to feel pain, are relaxed (or paralysed if a neuromuscular blocker used) and have no memory of what happens to them when they are under general anesthesia. This is achieved by interrupting the passage of signals along the nerves. This means that any stimulation to the body doesn't get processed or recognized by the brain. However, there are a number of kinds of anaesthetics and in some - such as local anesthetics which 'numb' a specific area - the patient is still fully conscious.
Surgical procedures, such as neutering, dentals and anything that is likely to be painful require anesthesia. Sometimes it may be necessary to place a pet under anaesthesia for procedures when it essential that they remain still, such as CT/MRI scanning, some x-rays, and for some samples to be collected.
These are injections, sprays or creams. They are normally used to block the sensation of pain along the nerve pathways, and can be used very successfully. Commonly local anesthetics are used in combination with general anesthesia to provide improved pain relief during and after surgery.
EMLA cream can be used when placing intravenous catheters or taking blood samples and is a local anesthetic in the form of a cream that numbs the surface of the skin, meaning the animal is less likely to move at the crucial moment when the needle punctures the skin. This type of anesthesia is not suitable for surgical procedures, since only the skin is numbed and the animal is still able to move and feel sensation.
Another example of a local anesthetic technique is a dental nerve block, where similarly to techniques used in people the nerves supplying sensation to the teeth can be blocked to prevent pain during and after a dental procedure. These techniques are used in animals under general anesthesia for a dental procedure to ensure that the animal stays still and receives adequate pain relief for the procedure.
A general anesthetic places an animal into an unconscious state where they are unable to move or feel pain. This is necessary for surgical procedures to be performed.
There are many drugs and combinations of drugs that can be given to achieve anesthesia. The choice of anesthetic is based on many deciding factors. The age of the animal, health status and the procedure to be undertaken, are all considered when deciding on which anesthetic to use.
Normally a premedicant is given first; this helps to relax the muscles and has a calming effect, but doesn't usually render the patient unconscious, other drugs or anesthetic gas is needed to achieve general anesthesia. Animals are usually maintained under anesthesia by an anesthetic gas delivered via an endotracheal (ET) tube placed in their trachea (windpipe). The ET tube also ensures that the animal has a secure airway throughout anesthesia, should an emergency occur.
Is anesthesia safe?
Yes and no!
No anesthetic is 100% safe, 100% of the time, and no two animals ever react the same to an anesthetic, but anesthesia has become far more reliable and safe over the last decade. Recent evidence suggests that the death rate during anesthesia in healthy dogs is about 1 in 1800 dogs and in healthy cats it is about 1 in 900 cats, suggesting that the risks of anesthesia are greater in cats than dogs. The risk of death increases in patients that are unhealthy.
Ways that risks of anesthesia are minimized include:
- Constant monitoring by trained staff when the pet is under anesthetic.
- Minimizing stress, before and after anesthesia.
- Keeping patients warm before, during and after surgery.
- Providing medication for pain.
- Placing an endotracheal tube to aid breathing and an intravenous catheter to supply fluids.
- Use of safe anesthetic drugs.
Lowering the risk however doesn't remove it completely, and there is always the risk that any patient may suffer an adverse reaction to the drugs, die under anesthetic, bleed excessively during or after surgery, or suffer complications.
Your vet will discuss the risks involved in any anesthetic, and the specific risks for the procedure your pet is undergoing.
Why do I need to fast my pet before an anesthetic?
Some anesthetic agents can make pets feel nauseous. It is really important that your pet does not vomit whilst under anesthetic or on recovery because there is a risk that they will inhale some of the vomit. Dogs and cats should not have anything to eat within 6-12 hours of an anesthetic so that their stomach is empty. If you think your pet may have had access to food you must let your veterinarian know when you take your pet in for an anesthetic and they will decide whether to reschedule the procedure.
Will my pet need special care following an anesthetic?
Your veterinarian will want to keep your pet in the hospital until they are sure that it is fully recovered from the anesthetic. Once your pet gets home they will probably want to rest quietly for 24 hours but should be eating and drinking normally by then. If your pet is uncomfortable following surgery they will be reluctant to eat, and therefore it is important to provide good pain relief to ensure a rapid recovery. Speak to your veterinarian if you are concerned that your pet is uncomfortable, restless or reluctant to eat.