General Anaesthesia in Horses Laura Hart BVM&S CertAVP MRCVS


ing and potentially dangerous thing to do even when they are healthy. Thanks to modern medicine and new techniques, we can safely perform many more routine and emergency procedures than we used to in merely sedated standing horses.


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That having been said there are some factors, which mean a general anaesthetic is necessary:


• Temperament – some horses have a natural temperament we cannot safely control with sedation alone e.g. some breeds, wild horses, individual cases.


• Age – some horses may be too young to be able to safely control with sedation alone e.g. foals.


• Health status – some procedures are simply too painful; for example to achieve safe control with sedation alone to treat or transport e.g. some fractures, extensive soſt tissue damage, unknown injuries.


• Weight – some procedures require a limb to be supported off the ground by an assistant for a prolonged time period which isn’t possible in our heavier patients so a general anaesthetic may be safer for all concerned.


• To eliminate movement – some surgery requires delicate precision and the horse to be motionless e.g. some orthopaedic surgeries.


• To reduce risk of contamination – some procedures cannot risk the surgical area becoming contaminated as infection would have catastrophic results and so it is performed under general anaesthetic to ensure the area can be scrubbed and a sterile surgical field created e.g. some joint surgeries


• Safety – an entrapped horse may require a general anaesthetic to achieve a safe environment for emergency services to work in, to speed the rescue of a human whose life is in danger and/or then safely rescue the entrapped horse


• Positioning – colic surgery requires a horse to lie up side down and so even a highly trained Police horse would require a general anaesthetic.


• Procedure – there are some situations which mean the horse must be completely anaesthetised e.g. colic surgery, caesarean section and some fracture repairs and dental procedures. A general anaesthetic is required in these scenarios due to a combination of the aforementioned factors not to mention the unpredictable length of the procedure.


In certain, very specific cases, general anaesthesia must be performed in the field; for example in the emergency entrapment scenario. For the reasons above, in order to reduce risk to the horse and create a safe controlled environment for veterinary staff, if a general anaesthetic is required, a fully staffed and equipped clinic or hospital is the best option wherever possible.


In this article we will talk you through an elective general anaesthetic in an otherwise healthy horse. Your horse will have undergone a clinical investigation with radiographs/scans/tests to determine what surgery is required or recommended. You will then likely talk to two vets, one the surgeon and the other the anaesthetist. They will each talk you through their plan, which will include the


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Due to the tight ring of muscle around the entrance to a horse’s stomach, they cannot vomit so we don’t ask you to starve them for hours and hours prior to surgery. However, in order to ensure your horse has a comfortable stomach, you will be asked to take food and water away a short period of time prior to surgery.


Aſter admission your horse will be groomed and made as clean as possible to reduce contamination of the operating theatre. Pre-anaesthetic blood tests are oſten performed to check your horse’s infection status and general health. Your horse’s anaesthetist performs a full clinical examination, which flags up any reasons not to perform the anaesthetic or identify factors, which may influence their anaesthesia plan. A catheter will be placed in the horse’s vein, your horse be weighed and will then be given any required pre-operative drugs such as antimicrobials or pain relief. At this stage it may be required to clip some hair from the surgical


orses are not physiologically designed to lie up side down or on their sides for long periods of time, which makes putting them under general anaesthetic a very challeng-


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