The ABCs of Cat Bloodwork: What Those Results Really Mean

One of the remarkable things about domestic cats is that they adapt to life as both predator and prey. They can hunt lizards, birds, and pesky shoelaces, but they also instinctively protect themselves from larger predators like dogs and coyotes by hiding pain to mask weakness. Since early disease detection can mean the difference between life and death, taking your beloved pet to a trusted AAHA-accredited veterinarian for cat bloodwork should be a key part of your overall approach to giving them the longest, healthiest life possible. Here’s what you need to know.

Why Feline Bloodwork is Essential

Routine bloodwork for cats will establish a baseline of what “normal” looks like for each individual cat. It helps veterinarians and pet parents know when something is wrong and needs to be addressed – and also shows health trends to monitor over time, according to Samantha O’Gorman, DVM, a veterinarian at AAHA-accredited Thrive Pet Healthcare in Natick, Massachusetts.

“It can give us a really good comprehensive look into the patient as a whole,” she says. “Obviously our cats can’t speak for themselves. Cats are really, really great at being stoic and hiding what’s wrong, and a lot of the signs that something is wrong are really subtle. So bloodwork can be a really valuable portion of the puzzle to help us keep our patients feeling healthy and catching things early so we can keep them with us for as long as possible.”

When and Why Your Veterinarian May Recommend Bloodwork

Veterinarians typically recommend feline bloodwork as part of annual wellness testing, as well as when a cat comes in for a sick visit.

“For sick patients, we can compare the previous healthy lab work that they had when they were feeling well to the labs when they’re feeling poorly,” Dr. O’Gorman explains. “That can help us assess the subtle things.”

For instance, even if a value on your cat’s bloodwork isn’t flagged as abnormal, your veterinarian can look at how it’s been trending over time and, if there’s a noticeable change, gain important clues to what’s happening that will guide treatment plans.

Cat bloodwork is also essential before surgery, since anesthesia drugs are metabolized in different parts of the body, she notes. Your cat’s veterinary team will check that kidney and liver values look good, and that platelet counts are high enough to clot blood properly.

“We just want to make sure that there’s nothing underlying that could be making it difficult for them to heal over time and that we do our due diligence to make sure every pet is safe,” Dr. O’Gorman says.

Another common time when a veterinarian will suggest a blood test for cats is to monitor whether a medication is working, such as when a cat is being treated for hyperthyroidism. After starting or adjusting medicine dosages, Dr. O’Gorman – whose own cat is named Tomcat Brady – typically likes to check bloodwork in 4-6 weeks.

Cats with chronic diseases benefit from more frequent bloodwork – every 3-6 months – though this can extend to every 6-12 months when they’re stable.

When cats enter their senior years – around 7-10 years old, depending on the breed – bloodwork is paramount, particularly since kidney disease and thyroid issues are so prevalent in older cats. Senior cat blood tests are complemented by also testing a urine sample as a key component of supporting your senior pet.

“It can give us a good look at the patient as a whole, including hydration status, to help us better understand what the values are saying,” Dr. O’Gorman says.

Thanks to veterinary research into kidney disease, with early detection through cat bloodwork and urinalysis, veterinarians can suggest management strategies involving diet changes, supplements, and medications to help a cat feel as well as possible for as long as possible.

“We have many cats with chronic kidney disease that live for many, many years very happily,” she says. “That’s always our goal.”

The Basics of Feline Bloodwork Panels

It’s natural to want cat bloodwork explained, and veterinarians are happy to discuss results with concerned pet parents. But it helps to know some basics.

Primarily, feline bloodwork involves a complete blood count (CBC) and chemistry panel. In a nutshell, the CBC calculates the number of cells in blood, including white and red blood cells (and hemoglobin, a protein carried by the latter) and platelets.

Meanwhile, the chemistry panel measures the liquid part of blood for a range of components such as blood glucose, sodium, cholesterol, potassium, calcium, and creatinine.

Though they are separate tests drawn from different vials of blood, a cat CBC and chemistry panel are virtually always done at the same time, according to Rachel Groveman, DVM, a veterinarian at AAHA-accredited LeadER Specialty Animal Hospital in Cooper City, Florida, who has three cats of her own.

“They’re run from separate tubes of blood, so you have to pull for both, but you almost never run one without the other, unless you’re just monitoring one specific value on a CBC,” she says. “If a cat was anemic (caused by low red blood cells) and you had already done complete blood work, you could just monitor the anemia with a CBC. But for the most part, when we’re looking at screening, we’re doing a CBC and a chemistry.”

Bloodwork results will show the cat’s values for each component alongside the normal range (aka reference intervals). If a cat has an elevated white blood cell count beyond what’s considered normal, it could be due to an illness or infection, or even cancer, she says. Low platelet counts can lead to bleeding disorders, while abnormally high platelets can increase the risk of heart attack and stroke from blood clots.

Through routine bloodwork, veterinarians can monitor blood sugar trends over time to keep an eye on a cat developing diabetes, which can develop slowly. Similarly, creatinine trends can alert the team to kidney disease.

Beyond the CBC and chemistry panel, kittens (and adult strays) often need an additional blood test for cats – retroviral testing – to screen for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). While there isn’t a specific test for feline infectious peritonitis (FIP), bloodwork can provide clues that lead to a diagnosis.

On the other end of the age spectrum, senior cats often benefit from a thyroid chemistry panel to see if thyroid hormones are elevated, since cats are prone to hyperthyroidism – which can lead to issues like high blood pressure and heart disease – as they age.

Due to the prevalence of kidney disease in senior cats, veterinarians might order an SDMA (symmetric dimethylarginine) test as part of diagnostic bloodwork; increases in the SDMA molecule can indicate early damage to kidneys.

Dr. Groveman emphasizes the importance of cat bloodwork to be able to catch and treat health issues as early as possible.

“Cats have very, very subtle signs of illness. They tend not to show illness until sometimes it’s a little too late,” she says. “Monitoring bloodwork is just one way to detect diseases early for them and make sure that they stay healthy and live as long as they can.”

Your Role in Maximizing the Value of Bloodwork

You and your veterinary team share a common goal: the best possible outcome for your pet. You are essentially partners in your cat’s care, so Dr. O’Gorman encourages pet parents to feel comfortable engaging in an open dialogue with your veterinarian.

“We, as veterinarians, are not going to bite. We’re always happy to answer questions,” she says. “We went to school for this. This is what we’re very passionate about. And most of us are very passionate in educating owners on why we do things as well.”

She hopes pet parents will be comfortable asking why certain bloodwork is necessary and sharing any financial concerns. For clients with budget issues, she might run a smaller chemistry panel each year – which can typically be done in-house and costs less than sending bloodwork to a lab – and a larger, more comprehensive panel every other year for wellness visits.

By communicating together and observing bloodwork trends over time, veterinarians and pet parents can make informed decisions about how to tailor care for cats. When a cat has elevated kidney values, the family might notice she is drinking more water. A cat being treated for hyperthyroidism might not be as hungry anymore. So, pet parents can become more aware of subtle behavior changes and generally more in tune with their cats.

Ultimately, understanding your cat’s bloodwork and working with your veterinarian to customize care can help you give your cat the best quality of life – and strengthen your bond.

“By understanding what each patient’s normal values are, we can make better and more nuanced medical decisions that are specific to that particular patient,” Dr. O’Gorman says. “It can also help people to feel more connected with their pets to fully understand what’s going on with their health.”