It is often routine to starve the horse overnight before surgery. Usually the horse is admitted in time for this to be undertaken at the hospital, but always check with your vet whether you need to withhold food yourself and for how long.
It is sensible to contact your insurer before any procedure; you will need their permission to operate to ensure it is covered under your policy.
Prior to anaesthesia the horse is weighed to ensure accurate drug dosage and subjected to a thorough pre anaesthetic examination. The heart and lungs are checked to detect any cardiac or respiratory problem as well as other vital signs such as temperature and mucus membrane colour to determine any health issues that might compromise the success of anaesthesia.
A pre anaesthetic blood test is run to insure that no muscle, liver damage or immunosuppression is present. The horse’s mouth is flushed and the area requiring surgery is clipped and prepared. Finally an intravenous catheter is placed in his jugular vein so drugs can be administered safely (Picture 1).
The horse is sedated to keep it calm before induction and it is led to the fully padded induction or ‘knock down’ box. The anaesthetist will administer an induction agent by injection. This is the initial stage of anaesthesia and will cause the horse to become unconscious and recumbent.
The surgical team is present to assist the anaesthesist and make sure the horse goes down quietly. The next step is to insert an Endotracheal Tube, through the mouth of the horse into the trachea (Picture 2). This tube will keep the horse’s airway open whilst delivering the anaesthetic gas to maintain the anaesthesia whilst on the operating table.
After induction as been completed successfully the horse is moved into the operating theatre using an overhead winch (Picture 3) which lifts the horse using hobbles on its legs. This may sound dramatic but it is a safe and effective way of lifting such a heavy animal.
Next the horse is positioned on the operating table (Picture 4). This is one of the most critical aspects of anaesthesia, as the horse must be positioned carefully to allow access to the area that needs attention without compromising blood flow to any muscles.
During surgery the anaesthesist is responsible for monitoring the vital signs, blood pressure, respiratory rate, heart rate and ECG. He must also constantly observe other parameters such as the amount of anaesthetic gas used and artificial ventilation (mechanical breathing assistance) if necessary. Nowadays this is done with the help of very reliable monitoring and anaesthetic machines which reduce the risks of anesthesia significantly. (picture 5)