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Why Does My Cat Need Blood Work before Anesthesia?

Posted March 15, 2015 in Cat Checkups & Preventive Care

Dr. Phil Zeltzman is a traveling, board-certified surgeon in Allentown, PA. His website is He is the co-author of “Walk a Hound, Lose a Pound” (

Zee Mahmood, a veterinary technician in Reading, PA, contributed to this article.

cat getting blood work done

Your veterinarian will likely require blood work before your cat has anesthesia for dental work or surgery. What is the point of running blood work? Is it a way to pad the bill? Is it a scam designed by veterinarians who want to retire on the beach?

Blood work is actually the easiest, fastest, cheapest and least invasive way to investigate, discover and monitor many health conditions. It is typically either sent to an outside lab or analyzed in-house, (i.e., at the clinic). Your cat's blood work is handled by well-trained technicians and performed on sophisticated, automated machines. The price of blood work is based on the cost of such advanced and accurate machines, sample preparation, sample handling by the nurses and the analysis by the veterinarian.

Why is blood work performed?
There are several reasons for this test, all with one goal in mind -- making sure that your cat is healthy enough for anesthesia and surgery. Since it is unlikely that your cat will tell the veterinarian what could be wrong inside, your veterinarian can use your cat's blood work to get a better understanding of what is going on beneath the surface.

What can be found from blood work?
There are two main parts in routine blood work: the chemistry and the Complete Blood Count (or CBC).

The chemistry consists of an analysis of various enzymes, proteins and other chemicals in the bloodstream. These levels can indicate healthy or unhealthy conditions of the organs. Liver function is analyzed to detect liver disease, Cushing's disease, trauma or the presence of a liver shunt, a rare condition that causes blood circulation to bypass the liver. Eliminating the possibility of a shunt is very important for any kitten undergoing anesthesia.

Kidney function is similarly analyzed to detect kidney disease. Ideally, kidney blood work goes along with a urinalysis to specify what type of kidney disease may or may not exist. Your cat's chemistry also investigates blood glucose or sugar. Electrolyte levels are measured to check for dehydration, metabolic disorders and kidney disease. The function of the pancreas and the thyroid function can also be tested. Older cats can have a hyperactive thyroid gland (hyperthyroidism), which is important to detect before anesthesia.

In addition to analyzing the chemistry of the blood, your veterinarian can run a Complete Blood Count. The CBC provides detailed information about the various blood cells and platelets. Low counts of certain blood cells can indicate hidden diseases such as anemia, bleeding or even bone marrow or immune system disorders. High counts of certain blood cells can indicate conditions such as dehydration, inflammation or infection.

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Dr. Phil Zeltzman is a board-certified veterinary surgeon and author. His traveling practice takes him all over Eastern Pennsylvania and Western New Jersey. You can visit his website at, and follow him at