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The Daily Vet by petMD

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.


Regular veterinary examinations are essential to keeping your cat healthy. Your veterinarian is skilled at spotting the signs of disease early, before your cat becomes seriously ill and while the disease is likely much more treatable. Since cats tend to mask disease so well, these visits are mandatory for ensuring a long, healthy life for your cat.

During the course of a routine veterinary examination, your veterinarian will conduct a thorough physical examination, checking your cat from nose to tail. However, your veterinarian will also likely recommend performing routine blood and urine testing for your cat as well. What can these blood and urine tests show that a physical examination might not? Let’s talk about some of the specific blood tests and why they are important. (We’ll talk about the urine tests in an upcoming post.)

A basic blood screen will likely consist of a complete blood count (CBC) and a blood chemistry profile. In addition, your veterinarian may recommend testing for thyroid hormone levels. Feline leukemia and/or feline AIDS testing may also be recommended, particularly if your cat’s leukemia and AIDS status is unknown. But exactly what are these tests and what do they look for?

A complete blood count examines your cat’s white blood cells, red blood cells, and platelets.

  • White blood cells (WBCs) are part of the body’s immune system. There are several types of white blood cells: neutrophils, monocytes, lymphocytes, eosinophils, and basophils. Each type of white blood cell reacts in a specific way to a threat to the immune system. A CBC counts not only the total number of white blood cells but also each individual type of white blood cell in the blood sample.
  • Red blood cells (RBCs) are the cells in the blood stream that are responsible for carrying oxygen to the different tissues in the body. A CBC measures the total number of RBCs as well as measuring their capacity to carry oxygen based on hemoglobin levels in the blood. (Hemoglobin is the protein responsible for transporting oxygen.)
  • Platelets are necessary for blood clotting. Without adequate numbers of platelets, your cat’s blood will not clot properly and your cat will be susceptible to abnormal bleeding. A CBC measures the number of platelets in your cat’s blood.
  • A CBC also examines the individual cells in your cat’s blood for evidence of structural abnormalities that might be an indication of abnormal function or disease.

A blood chemistry profile measures the various chemical compounds found in your cat’s blood stream. There are several chemicals that are commonly measured.

  • Blood urea nitrogen and creatinine are measured to evaluate kidney function. They may be elevated due to damage to the kidneys themselves or elevations may indicate other abnormalities in the renal system that impact the kidneys, such as urethral or ureteral obstructions or dehydration.
  • Chemical compounds used to evaluate liver function include alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin. Any or all of these values may be elevated in cases of liver disease, depending on the type of disease. Abnormalities in other organ systems can also cause changes in these values. For instance, adrenal disease can affect some of these values also.
  • Electrolytes are often included in a blood chemistry profile also. Abnormalities in electrolytes such as calcium, chloride, potassium, sodium, and phosphorus can be associated with many different disease conditions. Abnormalities in kidney function, gastrointestinal disease, seizures, and many other illnesses and/or symptoms can cause or be caused by abnormal electrolyte levels in the blood.
  • Blood protein levels are also often measured in a chemical analysis. Blood proteins serve many functions in the body. Globulins, a specific type of protein, play a role in immune function. Albumins, another type of protein, help stop fluid from leaking out of the blood vessels and help transport specific molecules to areas where they are required. Other proteins aid in clotting and help regulate gene expression. Typically, a blood chemistry profile will measure total protein levels, globulin levels, and albumin levels.

The measuring of thyroid hormones (usually T4) is performed when thyroid disease is suspected. Hyperthyroidism is a common disease, especially in middle aged and senior cats. It results in elevated thyroid hormone levels circulating in the blood stream.

Testing for feline leukemia and feline AIDS are often part of a basic blood screen as well. These diseases are both caused by retroviruses, although the feline leukemia virus is different from the feline AIDS virus. Testing for these viruses may be recommended if your cat has never been tested before, if your cat has been exposed to another cat that is positive for one of these viruses, if your cat is at high risk of exposure to either virus, or if your cat is ill.

More specialized blood testing may be indicated based on the results of these basic blood tests. However, these are the tests that are most commonly recommended as part of a routine blood screen to evaluate your cat’s overall health.

Dr. Lorie Huston

Image: Thinkstock

Comments  6

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  • Terminology
    08/19/2013 02:49pm

    We have the regular blood work done in younger cats here, and then they have what the lab is calling a "geri-panel" which is covering more information in the blood stream and automatically recommended for older cats. I presume that is when the "blood chemistry profile" is included? All our cats are a new batch of youngsters so we haven't had to consider any testing recently. Such a nice break.

    Of course it also becomes necessary to consider urine testing in older animals, too, but I guess you were just discussing bloodwork with this particular article? I know veterinarians prefer not to think about having to collect urine with some cats. (-;

    I always recommend to friends and associates that they get a copy of the lab work for a file at home in case of emergency. Sometimes it just might save some time, and some preliminary testing when a cat needs a quick solution.

    It was also very useful, one time, to have our own interpretation of the lab report when a substitute veterinarian was treating our FIV+ boy one time. The veterinarian had phone us to tell us our boy had cancer. The lab hadn't bothered to read the description of his conditions, and wrote on the bottom of his report that the results suggested he might have cancer, which he didn't. It was just the reduction in T-cell count that was reducing at a normal rate for a FIV+ cat. When I questioned the results with the veterinarian, she paid more attention to our boy's file and agreed that his blood work was normal -- for him.

  • 08/19/2013 03:05pm

    The blood chemistry profile in a younger cat might be an abbreviated version of that done in a geriatric profile. For instance, in a younger cat, electrolyte levels may or may not be measured. A thyroid screen may not be necessary for a younger cat either. It really varies between one veterinarian and another though. And what is done as a screening test for a healthy young cat may be different than that recommended for a cat that is sick also.

    We'll be talking about urine testing in another upcoming post. But you're right. Urine testing is an important part of monitoring feline health too. :)

  • Bloodwork Baseline
    08/19/2013 06:04pm

    All my critters get full bloodwork with every checkup (along with blood pressure). I feel it's important to have a good baseline and to be able to see if something is "creeping" up or down.

    I'm not particularly concerned with FIV unless a kitty has already been diagnosed (keeping an eye out for gum problems and infections) and unless he/she is a biter.

    I do get concerned when I hear it called "feline AIDS" instead of FIV, though, due to the connotation and the fact that many humans will panic instead of considering it just something to watch. I have one FIV+ kitty in my clowder and it's not a problem at all with the other kitties.

  • 08/19/2013 06:06pm

    P.S. My vet emails me lab results so I keep a copy on my phone so it's always handy if a trip to the emergency room is ever warranted.

  • 08/19/2013 10:40pm

    You are so right to be annoyed when you hear the term, "Feline AIDS". I don't personally think there is any such thing as cats don't deteriorate quickly enough to develop AIDS, in my experience. AIDS is a term used when the body can no longer defend itself from disease because the T-cell count is too low.

    Our boy went into mourning when we lost our dog, who was his close companion, (couldn't be around other cats due to aggression), and he kept developing fatty liver disease no matter what we tried. Eventually he had a heart attack, but it was NOTHING to do with FIV or AIDS.

    I am glad to read your cat can interact with other cats. It was very hard on our boy. I am sure he never understood why he had to be segregated.

  • 08/19/2013 07:44pm

    If you have multi-cats, the lab tests become very important. It's nice to establish a base-line of information from these tests. We have a senior kittie who is low in potassium, which requires lab work to monitor. Then there are the "kidney kitties", those who are on "social kidney diet" and the monitoring lets us know if the diet is helping. Every now and then, someone will "miss" the litter box and no one will admit this faux pas...thus, another test. Better kitties through chemistry! Thank goodness!

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