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Understanding Blood Tests For Cats: The Results Explained

Blood tests for cats are a valuable tool in most veterinary clinics. Our Clackamas vets explain why blood tests for cats are important and what each test result might mean.

Blood Work For Cats

When your veterinarian suggests blood work 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

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

Creatinine levels are more closely related to kidney function. High levels indicate that the cat's kidneys are having difficulty removing creatinine from the body and that kidney disease may be developing.

Alanine Aminotransferase (ALT) & Bilirubin

Blood chemistries such as ALT and bilirubin are commonly found in routine blood panels. They are mostly indicative of liver health, and a high level usually indicates liver dysfunction.


Blood sugar, or glucose, is typically tested on cats to see if they have diabetes mellitus, in which case the glucose result will be quite high. Additionally, low blood sugar can provide a veterinarian with important details about a cat's general health.

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

    In kittens and at intervals throughout adulthood, FELV and FIV are routinely tested for. It's crucial to monitor a cat's status with regard to these viruses because they are potentially fatal and cannot be treated once your cat becomes infected.

      Thyroxine (T4)

      With age, cats' T4 levels are typically checked. A high T4 could be a sign that hyperthyroidism, a cat condition that is frequently diagnosed, is developing. Cats with high thyroid levels may exhibit a wide range of symptoms, including an increase in appetite, weight loss, the desire for more human food or non-food items, and increased vomiting.


      Electrolyte levels, which include potassium, sodium, and chloride, can tell a veterinarian a lot about a cat's health, including hydration levels and organ function, particularly the kidneys. Electrolyte imbalances in cats can cause a variety of symptoms, including heart arrhythmias and muscle weakness.

      Why Your Vet Might Suggest Blood Work

      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 typically recommended as part of routine wellness checkups for cats of all ages, from kittens to geriatric cats. These are extremely beneficial in our mature patients, as we frequently see cats' health and happiness return to normal when blood tests detect illness early.Cat bloodwork, along with other bodily fluids such as urine, can help identify conditions that 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 We Learn From Your Cats Blood Test

      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 blood stream 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 issue 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.

      Once we've established a link, we can order any additional feline bloodwork or procedures required to diagnose and treat the condition. In this way, feline blood tests can help a veterinarian 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.

      If your cat is displaying abnormal behavior, maybe a blood test is in order. Don't hesitate to contact our Clackamas vets to schedule an appointment today.

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