Why We Recommend Pre-Anaesthetic Blood Tests and I.V. Fluid Therapy

hat is a pre-anaesthetic blood test?
This is a blood test that is performed prior to sedation/general anaesthetic. It is done the day the surgery/procedure (unless your veterinarian specifies otherwise).

What are the key benefits of getting this testing done?
Two of the organs responsible for processing anaesthetic are the kidneys and liver and disease of these organs is not always apparent when your veterinarian examines the patient in consult. Pre-anaesthetic blood tests enable us to detect any issues with these organs prior to giving sedation/anaesthetic drugs. With this information we can formulate a plan to better reduce the risk to these organs. This may involve changing the drugs used or even the entire approach to surgery. In very rare cases we may need to cancel surgery due to the findings on the blood tests.

We will measure the Packed Cell Volume (PCV) (% red blood cells) to make sure your pet is not anemic before starting the procedure. Some blood loss occurs during most surgical procedures. We do not want to begin a nonemergency surgery on a patient with a low PCV. A presurgical level is also important if excessive bleeding occurs during surgery or if we suspect bleeding internally after surgery in that we can compare post surgical PCV level with presurgical PCV levels.

We will determine the Total Protein content of the serum to make sure your pet is adequately hydrated. A dehydrated patient undergoing anesthesia could potentially result in kidney failure. Total protein is also important in interpreting the PCV level.

Which patients are these tests often recommended for?
Patients over the age of 6 years are more likely to have kidney and liver issues so pre-anaesthetic blood tests are often routinely recommended for these animals. Pre-anaesthetic blood tests may also be recommended if we are suspicious of disease. For example, if the animal is unwell or if there may be an internal disease causing the surgical condition.

What are intraoperative I.V. fluids?
These are fluids given intravenously (into the blood stream) before, during, and after a procedure/anaesthetic.

What are the key benefits of providing I.V. fluids?

  • The biggest side-effect of anaesthesia is hypotension (low blood pressure) and I.V. fluids help us to maintain/increase blood pressure. The kidneys, liver, and heart in particular are very sensitive to changes in blood pressure. If the animal already has some kidney/liver/cardiac issues, keeping blood pressure within a normal range becomes especially important.
  • We can replace fluids that might be lost during surgery. For example, if there is some bleeding, we can replace some of the fluids lost in the blood.
  • We help correct dehydration that might have occurred before surgery.
  • We can help correct electrolyte imbalances.
  • By having I.V. fluids in place, we are also more quickly able to give emergency drugs if needed.

Which patients are I.V. fluids often recommended for?
Patients over the age of 6 years are more likely to have issues with organs that are sensitive to changes in blood pressure, so I.V. fluids are often routinely recommended for these animals. I.V. fluids may also be recommended if we are aware of a medical condition which would benefit from their use (eg. kidney disease/liver disease/dehydration/heart disease). They may also be recommended if the animal is to have a long anaesthetic which increases their chance of hypotension (low blood pressure).