There is a decreasing scale of consciousness:-

  1. Awake
  2. Sedated
  3. General Anaesthesia
  4. Coma
  5. Death

As you go down that scale a patient’s respiratory system and blood system becomes more and more compromised, leading to increased risk of permanent damage to body cells.


Back in the middle ages potions containing bile, opium, lettuce, bryony and hemlock were used for general anaesthesia .  Unfortunately the combinations used are so toxic they often lead to patients being far too deeply anaesthetised and often this resulted in coma or even death.  If recovery were to occur this usually took days.


Inhalational anaesthetics started to become more popular in the 18th century with the discovery of nitrous oxide (laughing gas), which is often used at the dentists.  This unfortunately is not strong enough for more extensive and painful operations as it generally leaves the patient somewhere between sedated and general anaesthesia.  The advantage is the patient is much further away from coma and death and this lead to increased survival from minor procedures and faster recovery times.  This gas was often administered via a face mask so control of the patients breathing was poor.


From the 1950’s an anaesthetic gas called Halothane was discovered and has revolutionised anaesthesia in both humans and animals.  It is a much safer product with a higher level of safety.  Unfortunately it takes quite a long time to give the right level of anaesthesia and the depth of anaesthesia is quite slow to change.  It also has a lot of side effects on the heart and lungs so is not very safe in very ill or older patients.


A newer anaesthetic gas increased in popularity over the 1970’s and was the gas of choice in human medicine and this was called Isoflurane. Veterinary medicine caught up in the 1980’s and today the majority of veterinary practices use Isoflurane for anaesthesia due to the better heart and lung safety and quicker recovery times.


There is a newer anaesthetic gas now available that is the latest veterinary gas anaesthetic called Sevoflurane.  It is the anaesthetic agent of choice for human surgeries, especially for children.  This has been shown to be safer to the respiratory system compared with Isoflurane, it has a much wider area of safety to maintain animals within the state of general anaesthesia and is much smoother for induction and recovery.  This gas also has a much less pungent owner so does not irritate the respiratory system as much as the other gases.  This means it is the safest anaesthetic available for pets, particularly older animals.


At St Clair we are pleased to announce we have recently converted all of our anaesthetic machines to use the state of the art sevoflurane anaesthetic gas.  This means you can be reassured that your pet is in the safest hands possible when it comes in for any general anaesthetic.   You should also notice a quicker, smoother recovery from the anaesthetic compared to other practices that are still using isoflurane.


At St Clair, we are different as all of our anaesthetised patients are monitored by a qualified and Registered Veterinary Nurse, meaning each anaesthetic is safer for your pet.