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Both sedations and general anaesthetics are performed every day in veterinary practice, and are required for all sorts of procedures. In many aspects, the two are quite similar, but they have very different uses. Let’s look deeper into what both sedation and general anaesthesia entail, and how they are different.
What is sedation?
A sedation means giving particular drugs in order to make them very relaxed and sleepy. Sedation is very useful to keep animals calm and still for minor procedures. Sometimes, we need sedation just to keep an animal still for things like x-rays, something that is easy for us to do, but not so easy to ask our furry friends to do! We may also need to use it to get a better look at some areas, like ears and feet. It gives the vet an opportunity to do a more thorough examination without particularly stressing the animal. Generally, the procedure sedation is used for tends to be shorter.
A sedation may be achieved by giving an injection into muscle, or via an intravenous catheter. Different drugs will be chosen depending on the animal health history and the procedure. They should be monitored throughout, checking on their heart and lungs. Often, the sedation can be partially ‘reversed’ to help wake the animal up once the procedure is over.
What is an anaesthetic?
General anaesthesia, or a GA, is a state of controlled but complete unconsciousness. An animal under anaesthesia will not be aware of any procedures happening to them, and they will not feel pain. However, their respiratory and cardiovascular functions may become impaired. Day-to-day, animals will be placed under general anaesthesia mostly for surgery, but also for procedures such as endoscopy (video scope of the GI tract) and bronchoscopy (video scope of the respiratory system).
The process of a general anaesthetic starts with a ‘pre-medication’, a combination of drugs to initially make the animal calmer and sleepier. This can be given into the muscle, or via an intravenous catheter. Once these first drugs have taken effect, the vet will induce anaesthesia with another anaesthetic drug which will place them into a state of unconsciousness. At this point, airway access will be gained, usually by placing an endotracheal tube (a long plastic tube which fits snugly into an animal’s windpipe). This allows an inhalational anaesthetic drug and oxygen to be delivered. It also allows us to help the patient breathe if they need it. The patient will be closely monitored throughout by a qualified professional, with the help of advanced monitoring equipment. At the end of anaesthesia, they will gradually gain consciousness again as the anaesthetic drugs wear off.
So, what’s the difference?
The big difference between the two is the level of consciousness achieved by both. While sedated, an animal will still be conscious and may be aware of what is going on. Deep sedation is just like being asleep. General anaesthesia is a state of controlled unconsciousness, so won’t be aware of what is happening to them. Changes to the cardiovascular and respiratory systems are a risk for both, but are far more likely to happen under general anaesthesia. An animal’s ability to breathe for itself may be particularly affected under GA, hence why we secure their airways with a breathing tube.
Perception of pain
This next concept might be trickier to get your head around, and that is an animal’s ability to feel pain under sedation vs under anaesthetic. Pain is consciously perceived, and a subjective experience with both physical and emotional elements – meaning that technically an animal will only feel this when awake and aware.
Therefore, an animal under sedation will be able to feel pain, whereas an animal under a general anaesthetic will not. An anaesthetised animal will instead respond to nociception – the response when the nervous system is met with actual or potential tissue damage. The body will still respond to this, and interventions can be made to manage the nociception, just as we would when an animal is conscious and perceiving pain.
Type of procedure
Generally, sedation will be used for shorter, less invasive procedures. General anaesthesia will be used for longer and more invasive procedures, like surgery and dentistry. The veterinarian will decide which is most appropriate for the procedure that they’re performing.
- Is Sedation Safer Than Anaesthesia? A Review of Currently Available Sedation Regimens – WSAVA2011 – VIN
- Veterinary and Human Anaesthesia: An Overview of Some Parallels and Contrasts – J. Carter, D. A. Story, 2013
- How safe is an anaesthetic in dogs really? – Vet Help Direct
- How dangerous is an anaesthetic for my cat? – Vet Help Direct
- Shoop-Worrall, S., O’Neill, D., Viscasillas, J. and Brodbelt, D., (2022) Mortality related to general anaesthesia and sedation in dogs under UK primary veterinary care. Veterinary Anaesthesia and Analgesia, 49(5), pp.433-442.