Pet bloodwork, explained: what those numbers tell us

You drop your dog off for a sick visit, or your cat for her senior checkup, and a little while later someone hands you a printout full of abbreviations. CBC. ALT. BUN. Creatinine. A few numbers have little arrows next to them. It looks like a secret code.

We will always translate. But it helps to know the basics, because bloodwork is one of the most useful tools we have, and it is less mysterious than it looks.

The two tests we run most

Almost every blood panel starts with the same two pieces. The first is a complete blood count , or CBC. That one counts cells: red blood cells, which carry oxygen; white blood cells, which fight infection and inflammation; and platelets, which help blood clot. Too few red cells points toward anemia. A shift in white cells can mean infection, inflammation or plain old stress.

The second piece is a chemistry panel . Instead of counting cells, it measures the chemicals in the liquid part of the blood. That is where we get a read on the kidneys, the liver, blood sugar, protein levels and electrolytes like sodium and potassium. For older cats and any pet with a suspicious weight change, we usually add a thyroid level too.

Our in-house lab runs both of these, plus urinalysis and fecal exams, and results are usually back within the hour. If your dog is vomiting, we would rather know whether his kidneys are involved before you leave the parking lot. You can read more about what we run on site on our diagnostics page.

A few numbers worth knowing

• BUN and creatinine are the classic kidney numbers. When the kidneys slow down, waste builds up in the blood and these climb. Dehydration nudges them up too, which is why we often ask for a urine sample as well.
• ALT and ALP are liver enzymes. A bump can mean the liver is irritated, but they also rise with certain medications, muscle injury and an overactive thyroid, so we read them alongside everything else.
• Glucose is blood sugar. High can mean diabetes, though a scared cat on an exam table can run it up all by herself.
• T4 is the main thyroid value. In older cats it tends to run high with hyperthyroidism. In middle-aged dogs it tends to run low with hypothyroidism. Same test, opposite worries.

One number alone rarely tells the story. A mildly high liver enzyme in a happy, bouncy dog is a very different conversation than the same number in a dog who has lost four pounds. We look at the whole picture, including what you tell us is going on at home.

Why we want bloodwork when your pet seems fine

If Biscuit is acting normal, why poke him? Two reasons. The first is that pets are very good at hiding illness, cats especially. In one study that screened 259 cats their owners believed were healthy, about one in five turned out to have a problem already, most often early kidney disease or an overactive thyroid. Those cats were eating and purring at home. Blood is simply harder to fool than a food bowl.

The second reason is baselines. Every pet has their own normal. If we know what your dog's kidney values looked like at age four, a small creep upward at age eight means something, even if it is still inside the printed reference range. This is why we build a blood panel into senior exams for pets over seven and recommend those visits every six months. You can see how those work on our wellness exams page.

Kidney disease, thyroid trouble and diabetes are all far easier to manage when we catch them early. Catching them early almost always means catching them on paper before you see them on the couch.

What the draw is actually like

Most pets handle a blood draw better than their people expect. A technician holds your pet gently, we take a small sample from a leg or neck vein, and the whole thing takes less time than reading this paragraph. Some dogs never stop wagging. Some cats have opinions, and for those we go slow, use a quiet room and sometimes a little something to take the edge off. Nobody is wrestled.

If we are running the sample in house, you can often wait or run a quick errand and come back. Anything we send to the reference lab takes a business day or two, and we will call you either way. If the printout confuses you, ask. We would rather spend five minutes explaining than have you worrying in the car.

When to call us

If your pet is drinking or urinating more than usual, losing weight without trying, eating less, vomiting more than once, or just seems off in a way you cannot put your finger on, that is a good reason to call. Bloodwork is often the fastest way to find out whether something is going on inside. And if your senior dog or cat has not had a panel in the last year, now is a good time to schedule one before the holidays get busy here in Nashville.

Call us at (615) 833-4423 or book online, and we will get your pet on the schedule. We will happily walk you through every arrow on the page.