Pre-surgical Bloodwork by Amanda Ransome, RVT

Why does my pet need bloodwork before surgery? This is one of the common questions asked when admitting a pet for a surgical procedure. Surgery can be a scary topic for many owners as it can cause a lot of stress and anxiety since there is always some risk involved with any surgical procedure.  Checking blood work before surgery helps determine an animal’s healthy status so that this risk can be minimized.

This is why pre-surgical blood work is recommended in all animals no matter what stage they are at in life.  Pre-surgical blood work may be offered as option for younger pets but is considered a mandatory part of the surgical protocol, especially in senior pet (over 6 years of age) as older animals have greater risks when placed under anaesthetic.

Bloodwork can tell you a lot about how your pets’ organs are functioning and can detect underlying conditions that may not be found during a physical exam, especially when there are no signs or symptoms present.  Pre-surgical blood work can also provide us with blood values that we can use as a baseline for future testing and monitoring by comparing values to determine how an animal’s health has changed.  Depending on your clinic, pre-surgical blood work can be performed either a few days prior to surgery or on the day of surgery.

What is included in a pre-surgical blood screening panel?

Pre surgical bloodwork panels consist of a complete blood count, a chemistry panel and electrolytes.

Complete Blood Count (CBC):

Red blood cells (RBC) – Deliver oxygen to tissues in the body.

Platelets – Cells that are involved in blood clotting.

White blood cells (WBC) – Primary defense against infections.

Packed cell volume (PCV) – Percentage of red blood cells in the blood.

These cell levels help screen your pet for blood disorders such as anemia, blood clotting disease, inflammation, infection, autoimmune disease as well as assess the hydration of your pet. 

Chemistry Panel-

Liver –

Alanine transaminase (ALT) – Present in the liver and increased in the blood when there is a liver disease.

Alkaline Phosphatase (ALP or ALKP) – Present in the liver and tissues and increased in the blood with liver disease and conditions.


Blood urea nitrogen (BUN) – Produced when proteins that are produced in the liver are broken down and excreted by the kidneys.

Creatinine (CREA) – Produced by the liver and help carry energy to the muscles where it is metabolized and excreted by the kidneys.

A change in these values can indicate impaired functioning of the kidney and liver which are the major organs in the body that are responsible for metabolizing and excreting waste.

Blood Glucose-    Measures the amount of sugar in the blood stream.  An increase in glucose can detect diabetes in your pet although may sometimes be due to stress in cats.

Total Protein (TP)-

Albumin- Proteins produced by the body to keep fluid from leaking out of the blood vessels.

Globulin- Proteins produced by the body that are an important part of your pet’s immune system.

These proteins help determine the hydration of your pet as well as liver, kidney and intestinal disorders.


Sodium (NA), Potassium (K), Chloride- 

Balance of these electrolytes is critical to the health of your pet.  Electrolyte levels help to determine dehydration, kidney function, endocrine disease and other abnormalities.  Electrolyte imbalances should be corrected before certain procedures are performed.

All of these blood values play an important role in providing your veterinarian with the tools needed in choosing the safest and best anaesthetic protocol for your pet. As anaesthetic drugs are processed by the liver and kidneys and eliminated from the body, impairment of one or more of these organs can prolong elimination of these drugs from the body and can increase your pet’s risk under anaesthesia and during recovery.  Any severe dehydration and electrolyte imbalances should be corrected prior to surgery and any abnormal values detected should be discussed with your veterinarian.  From there, you and your veterinarian can decide on the most appropriate options for your pet.

The number one goal of our Brampton veterinarian team is your pet’s wellbeing and providing your pet with the safest surgical protocol for anaesthesia and surgery.  Pre-surgical blood work can provide owners with peace of mind in knowing that their pet’s risk for surgery has been minimized.