Blood tests before anaesthesia?
Screening your pets’ blood prior to giving an anaesthetic is always a good idea!
It can significantly reduce medical risk and provide baseline levels, which become part of his/her medical records for future reference. We certainly find some parameters that are raised which were unexpected especially if your pet appears to be in good health. This helps us tailor your pet's anaesthetic and provide the correct level of fluid level required, this can reduce the risk of complications. On occasion we may re-schedule your pet's procedure so that we can treat whatever has arisen if that is deemed necessary. If the tests are within the normal ranges then we can proceed with confidence, knowing that anaesthetic risk is minimised.
The anaesthetics that we use here are similar, and in many cases the same, as are used in human medicine. They are gold standard in the veterinary field and the risk from receiving an anaesthetic remains very low in our patients.
One of the less welcome effects of anaesthetics and sedations is the reduction in blood pressure (called hypotension). The deeper or longer the anaesthetic the lower the blood pressure can go. When this happens the body is under increased stress to try and keep the blood at an adequate pressure. This makes the organs work much harder. Young, old and sick animals are especially at risk from this, as their organs are already working at a high capacity.
If the blood pressure is reduced for a long period of time then the organs can become damaged, aggravating disease which has not yet become apparent. If severe hypotension occurs, the brain and heart can be damaged. To help prevent this happening we use intravenous fluid therapy.
By placing a patient on intravenous fluids it becomes possible to elevate blood pressure to a relatively normal level. This reduces the stress to the heart and other major organs, reducing likelihood of circulatory failure during anaesthesia.
In an ideal world all anaesthetised patients would receive intravenous fluids as it is a preventative measure and we do this at White Cliffs Vets. Elderly, ill and young patients find it harder to cope with hypotension. Not only does it increase their risk from general anaesthesia but prolongs their recovery.
If there is an underlying kidney problem then the drop in blood pressure may cause kidney failure that cannot necessarily be repaired. If intravenous fluids are used the flow of blood to the kidneys is stronger, reducing risk of damage and helping flush the anaesthetic out of the system post operatively.
Healthy adult animals are less at risk from hypotension; their bodies generally are able to cope with the extra stress of being under anaesthesia although it is difficult to predict what effect the anaesthetic will have on the animal's body. So while not essential, we would recommend that they are used where funds allow.
Pre-anaesthetic blood testing involves a small sample of blood being taken from a vein in the leg or neck. Blood is tested for liver and kidney damage, diabetes, protein and electrolyte levels. The red blood cell number and white blood cell numbers are checked to make sure your pet is not anaemic or infected.
Intravenous fluids are given through an intravenous catheter, which is placed in a vein in the leg. This is secured in place and then a type of sterile saline solution is given before, during and after the surgery. All animals undergoing surgery have an intravenous catheter placed in them for surgery. Your pet may go home with a small bandage on their leg and this is where the catheter will have been placed. This bandage, if not removed by us, will need to be removed later on in the evening. Intravenous fluids cost varies slightly depending on how long they are needed and how big the pet is. Both preoperative blood testing and intravenous fluid therapy will often be covered by insurance policies.
If you have any questions please do not hesitate to ask either one of the vets looking after your pet or one of our nurses who will be only too pleased to help.