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Understanding Blood Tests for Cats

Your cat will have a variety of testing done throughout their life, including bloodwork. These tests help detect diseases and protect their overall health. Here, our Crystal Lake vets talk about the different types of blood tests for cats, why they are needed and when they might be done.

The Purpose of Blood Tests for Cats

If your cat needs bloodwork for the first time then you have questions about what the vet is looking for and why they need to have it done. Knowing what to expect can help to put your mind at ease.

Let's begin by discussing some of the most commonly performed blood tests for cats.

Complete Blood Count (CBC)

A CBC, or complete blood count, measures and examines a cat's blood cells. Some of the information that your vet obtains with this blood test includes:

  • 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 are responsible for forming blood clots.

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

Blood urea nitrogen (BUN) and creatinine are blood chemistries that are routinely measured as part of larger blood panels. If the BUN is high, it can indicate dehydration, kidney dysfunction, or a liver problem.

Creatinine is specific to kidney function. High levels indicate that the cat's kidneys are having difficulty clearing the creatinine from the body, indicating that kidney disease may be developing.

Alanine Aminotransferase (ALT) & Bilirubin

ALT and bilirubin are blood chemistries that are also often present in routine blood panels. High levels of ALT and bilirubin indicate issues affecting the liver.

Glucose (Blood Sugar)

Glucose, or blood sugar, is mostly tested to determine whether a cat has diabetes mellitus, during which the glucose result will be quite high. If your cat is showing low blood sugar levels it can point to other conditions allowing your vet to continue with secondary testing.

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

    FELV and FIV are routinely tested for in kittens and periodically throughout adulthood. These viruses are life-threatening and can't be cured once your cat gets infected, so it's important to keep tabs on a cat's status.

      Thyroxine (T4)

      T4 is usually monitored in cats as they get older. A high T4 might indicate the development of hyperthyroidism, a commonly diagnosed condition in cats. High thyroid levels can cause a myriad of different signs in cats, including increased appetite, weight loss, eating non-food items or wanting more human food, and increased vomiting.


      Electrolyte levels, including potassium, sodium, and chloride, can tell a veterinarian a lot about a cat's health status, including information about hydration levels and organ function, especially the kidneys. Electrolyte imbalances can result in many signs of illness in cats, including heart arrhythmias and muscle weakness.

      When should my cat have blood tests?

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

      During your cat's initial vet visit: 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.

      As part of their routine exam: 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 and other bodily fluids like urine can help identify conditions the examination portion of a physical cannot.

      When they are sick: Cat blood tests are suitable for cats that are not displaying any overt signs of illness, disease, or injury, but are acting abnormally.

      Prior to 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.

      Cat Blood Test Results: Explained

      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, otherwise known as hypoalbuminemia. Albumin is a protein that is produced by the liver to help regulate blood volume and fluid retention.
      • 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.

      Blood tests for cats serve as very valuable tools in a veterinarian's toolkit for helping to detect, identify, diagnose, treat, and ultimately prevent 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.

      Is your cat showing signs of an internal medical condition? Contact our Crystal Lake vet specialists to learn more about referrals to our animal hospital.

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      Companion Animal Specialty and Emergency Hospital is accepting new patients! Our specialists and experienced emergency veterinarians are passionate about restoring good health to animal companions in Crystal Lake.

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