An elderly cat is brought to our hospital because she is flooding her litter box with urine and drinking her water bowl dry. She also seems to be losing her appetite, along with a substantial amount of weight.

A 6-month-old puppy comes in for his neuter surgery. He has a history of excellent health at his previous puppy wellness exams, and appears in great shape.

A large-breed dog who is entering her mature adult years comes to us for her first senior wellness check. Although she’s growing older, she shows no signs of slowing down.

These three scenarios may not seem to have much in common, but they are linked by a common thread—all these pets will need blood work. You may wonder why these three seemingly healthy dogs would need blood work, but they require the same internal evaluation as a sick pet. You may also wonder what blood work could reveal about these pets’ health. Read on for Twin Lakes Veterinary Hospital’s guide to the ins and outs of blood work results, why blood work is necessary, and when your pet may require this testing. 

What does blood work for pets include?

Blood work is a general term that includes a variety of tests that are tailored to diagnose a potential medical problem in your pet, or to evaluate their health. Most commonly, blood work consists of the following tests:

  • Complete blood count (CBC) — A complete blood count is exactly that—a quantitative analysis of your pet’s blood cells. A CBC counts the number of red and white blood cells, and platelets in your pet’s blood, and compares the numbers to the normal standard for their species. Red blood cells are also evaluated for size and uniformity, and hemoglobin content. White blood cells are divided into their various types, with elevated or decreased numbers indicating certain disease processes.
  • Blood chemistry panel — A blood chemistry panel evaluates organ health and function, measures electrolytes, and assesses circulating enzyme levels. A panel can encompass a few values that focus on a specific organ’s function, to a wide range of tests that look at total-body health and function. Your pet’s needs will determine the appropriate blood chemistry panel type. 
  • Thyroid hormone (T4) testing — A separate, yet common, test, a T4 is often included in an older pet’s blood work to measure the thyroid hormone level in the blood in response to thyroid gland function. 

More specialized tests, such as endocrine disorders, organ dysfunction, and various infections, can help diagnose a multitude of pet diseases, and to measure drug levels in the body. 

What do blood work results for pets mean?

Interpreting your pet’s blood work results can be tricky without a veterinarian by your side, but those numbers boil down to:

  • Red blood cells (RBCs) — An increase in red blood cells can mean dehydration, while a decrease can indicate anemia.
  • White blood cells (WBCs) — WBC elevations can indicate infection, and some forms of cancer. Decreased levels can mean a viral infection, bone marrow abnormalities, or an overwhelming infection.
  • Platelets — A low platelet level indicates clotting issues.
  • Creatinine (CRE) and blood urea nitrogen (BUN) — These two enzymes help evaluate kidney function and hydration status.
  • Alkaline phosphatase (ALP) and alanine aminotransferase (ALT) — These two enzymes can fluctuate, based on liver function and various health issues, such as Cushing’s disease, bile duct problems, certain cancers, metabolic disorders, and toxin ingestion.
  • Calcium, phosphorus, potassium, chloride, and sodium — These electrolytes are essential for the body to carry out its normal processes, and any disturbances can pinpoint problems with bodily functions. 
  • Glucose — A mildly elevated glucose level can mean your pet is stressed or excited, while a significantly high level could indicate diabetes.
  • T4 — A high T4 means your pet’s thyroid is producing too much thyroid hormone (i.e., hyperthyroidism), while a low T4 means the opposite (i.e., hypothyroidism). Cats are more prone to hyperthyroidism, while dogs generally develop hypothyroidism.

When do pets need blood work?

All pets need blood work at some point. The most common reasons your pet will need blood work include:

  • Health evaluation — Performing blood work as part of your pet’s wellness exam helps us evaluate their health status. We can record their normal baseline when they are healthy, and then be able to spot subtle changes over time that may indicate disease development. Finding diseases early gives your pet the best prognosis and easiest treatment course.
  • Pre-anesthetic screening — Evaluating your pet’s health before anesthesia helps us formulate their safest possible anesthetic protocol, spot potential problems that will need monitoring throughout anesthesia and recovery, and to be ready to adjust our plan, as needed.
  • Illness — If your pet is vomiting, has diarrhea, or otherwise seems unwell, a blood work panel can help determine the cause. Blood work, paired with a thorough physical exam, can provide the clues for diagnosing your pet’s illness.
  • Therapeutic drug monitoring — Pets with chronic conditions, such as osteoarthritis, diabetes, or thyroid disease, require lifelong medication to enjoy a good quality of life. However, medications that treat these conditions must remain in the therapeutic range to avoid adverse side effects, so regular monitoring through blood work is necessary.

Whether your pet is ill or due for their annual wellness exam, they’ll likely need blood work to take an inside look at their health. Contact our Twin Lakes Veterinary Hospital team to schedule your pet’s wellness examination and blood work.