Pre-anesthetic Bloodwork in Veterinary Medicine

Have you ever taken your pet in for a surgery…even a seemingly minor one…and your veterinarian requested “pre-anesthetic bloodwork” first?  Some pet owners are leery of this and the extra cost that typically accompanies it; but before you decline it, you should know how important it is. 

Pre-anesthetic bloodwork is often recommended for all animals that will undergo anesthesia, no matter how major or minor the procedure is.  This allows your vet to assess your pet’s overall health and will often give indication of any underlying conditions that may not be seen on physical examination.  At some veterinary hospitals, younger animals may be exempt from pre-surgical bloodwork unless otherwise indicated by the doctor based on the pet’s health history.  It is typically highly recommended and sometimes even mandatory for older animas, though, because the risk of underlying conditions or possible anesthetic complications are much higher as an animal gets older. 

Bloodwork before surgery also gives the vet a chance to potentially alter the drug protocol for sedation and anesthesia to a different combination of medications that are safer for that specific animal.  Every drug has its side effects, and the best possible outcome is always desired for every patient. 

Typically, your vet will request that the bloodwork consist of a complete blood count (CBC) and a serum biochemistry.  This may vary slightly depending on the species, age, and current health condition of the animal.  The CBC will primarily assess the red blood cells, white blood cells, and platelets in the blood.  This may indicate if there is anemia, inflammation, infection, or if your pet is at a greater risk of excessive blood loss during surgery.  The serum biochemistry examines levels of several chemicals in the blood associated with organ function.  In general, it will include values that assess the animal’s liver, kidneys, blood glucose, serum proteins, and possibly other parameters depending on the type of biochemistry requested.  This portion of the bloodwork is very important as the kidneys and the liver play a large part in how the body metabolizes the sedative and anesthetic medications.    

If abnormalities are found on the bloodwork, there are several potential outcomes.  Some slight abnormalities are mild and may just be due to the pet being under stress at the time.  In these cases, your vet will likely proceed with anesthesia without further testing or interventions.  In some cases, it may be recommended to recheck the values in the near future to ensure any abnormalities are not significant.  In some cases, the preanesthetic bloodwork may detect something abnormal that can be corrected prior to surgery.  An example of this would be if mild dehydration is indicated.  In this case, your veterinarian may administer intravenous fluids for several hours prior to anesthesia to ensure your pet is as medically stable as possible.  If more significant abnormalities are detected, the veterinarian may recommend postponing surgery until more testing or treatment can be performed. 

Bloodwork shouldn’t be harmful to your pet and always comes recommended to ensure a safe surgery and smooth recovery.  With this better understanding of pre-anesthetic bloodwork, you will be able to make the right decision for your pet next time you are given the option.