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Understanding Blood Tests for Cats

Understanding Blood Tests for Cats

Bloodwork for cats is a valuable diagnostic tool in most veterinary clinics. In this post, our Lexington vets explain why blood tests for cats are important and what each test result might mean.

Feline Blood Tests

When your veterinarian suggests bloodwork for your cat, you may not be sure what they are looking for. Even the most experienced pet owners can be terrified of not knowing why their cat needs a medical procedure and what the results mean.

 Below are some of the common blood tests done on cats and what they tell the veterinarian.

Complete Blood Count (CBC)

A CBC measures and examines a cat's blood cells. It gives the veterinarian a wealth of information. Some of these include:

  • Red blood cell (RBC) counts, proportions, and health - RBCs carry oxygen, iron, and other nutrients around the body.
  • White blood cell (WBC) counts, proportions, and health - WBCs help fight inflammation, infection, cancer cells, and parasitic intruders.
  • Platelet counts and health - Platelets control blood clotting.

A CBC can tell a veterinarian if a cat is anemic, dehydrated, fighting off inflammation or an infection, and whether your cat has internal bleeding.

BUN & Creatinine

BUN and creatinine are two blood chemistries that are routinely measured as part of larger blood panels. A high BUN level may indicate dehydration, kidney dysfunction, or a liver problem.

Creatinine levels are more closely associated with kidney function. High levels suggest that the cat's kidneys are having difficulty removing creatinine from the body and that kidney disease is developing.

Alanine Aminotransferase (ALT) & Bilirubin

Routine blood panels frequently contain blood chemistries such as ALT and bilirubin. They are mostly indicative of liver health, and if they are abnormally high, it usually means there is a problem with the liver.


Glucose, or blood sugar, is usually tested to see if a cat has diabetes mellitus, in which case the glucose level will be quite high. Low blood sugar levels can also give a veterinarian important information about a cat's overall health.

    Feline Leukemia Virus (FELV) & Feline Immunodeficiency Virus (FIV)

    Kittens are routinely tested for FELV and FIV, and adults are tested periodically throughout their lives. It's crucial to keep track of your cat's health in relation to these viruses because they are life-threatening and cannot be treated once your cat has been infected.

      Thyroxine (T4)

      As cats get older, their T4 levels are frequently checked. Cats frequently develop hyperthyroidism, which can be detected by a high T4 level. Cats with high thyroid levels may experience a range of symptoms, including increased appetite, weight loss, eating non-food items or craving more human food, as well as more frequent vomiting.


      Potassium, sodium, and chloride, which make up electrolyte levels, can reveal a lot to a veterinarian about a cat's health, including hydration levels and organ function, particularly the kidneys. Heart arrhythmias and muscle weakness are just two of the symptoms that electrolyte imbalances in cats can produce.

      When Bloodwork May Be Necessary

      There a many reasons your vet might suggest bloodwork for your cat. Here are the most common reasons:

      It's your cat's first exam - We recommend blood work at the time of your cat's first exam because it helps us establish baseline health, check for any congenital abnormalities or potential concerns, and help us form an individual wellness plan for your cat.

      During semi-annual and annual wellness exams - Cat blood tests are usually recommended for all life stages from kittens to geriatric cats as part of their routine wellness checkups. These are extremely beneficial in our mature patients, as we often see cats' health and happiness return to normal when blood tests catch illness early. Cat bloodwork, along with other bodily fluids like urine, can help identify conditions the examination portion of a physical cannot.

      If a cat seems sick - Cat blood tests are suitable for cats that are not displaying any overt signs of illness, disease, or injury, but are acting abnormally.

      Before surgery - Cat blood work is used to determine the general health of the liver, kidneys, and other organs, which helps a veterinarian select the safest form of anesthesia. Bloodwork can also help determine the surgical risk level in all cats, especially elderly or injured patients.

      What Your Cat's Blood Test Can Tell You

      The results of feline blood tests are essential to helping veterinarians diagnose and treat medical conditions both within the blood itself, as well as in organs such as the kidney and liver. During a blood test for cats, various chemicals in the bloodstream are analyzed. Some examples are:

      • Cat blood tests can indicate a deficiency in albumin levels, which indicates a possible liver issue because albumin is produced in the liver, or intestinal or kidney issues as albumin can be lost if these are diseased.
      • Blood tests for cats can detect abnormal hormonal-chemical responses to environmental and internal stimuli, which indicates a potential issue with the patient's endocrine system.

      We can then order any additional feline bloodwork or procedures required to diagnose and treat the condition once we've established a link. In this way, feline blood tests are extremely valuable tools in the toolbox of a veterinarian for detecting, identifying, diagnosing, treating, and, ultimately, preventing illness or disease.

      Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

      If your cat is showing signs of illness, a blood test may be necessary for a diagnosis. Contact our Lexington vets to book an appointment today.

      Emergency Care

      Bluegrass Veterinary Specialists + Animal Emergency is open 24/7 for emergencies and is accepting patients for advanced diagnostic appointments. Our experienced vets are passionate about the health of Lexington companion animals. 

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      Contact (859) 268-7604