Your dog just turned 8, and at his annual checkup the vet recommends a “senior bloodwork panel.” You nod along, they hand you an estimate, and suddenly you’re staring at a list of acronyms, BUN, ALT, T4, CBC, wondering what any of it means and whether you actually need to spend the money right now when he seems perfectly fine. I’ve had this exact conversation in the exam room hundreds of times. Here’s what I wish every pet owner knew before that appointment.

Why Bloodwork Matters More in Senior Pets Than You Think

The honest answer to “does my healthy-seeming older pet really need this?” is yes. The reason comes down to one frustrating biological fact: dogs and cats are masters at hiding illness. It’s a survival instinct baked in over thousands of years. By the time a pet is visibly slowing down, drinking more water, or losing weight, organ disease is often well advanced.

Take kidney disease. A cat can lose 70 percent of kidney function before showing any symptoms you’d notice at home. Caught at 50 percent loss through routine bloodwork, the disease is manageable for years with diet changes and sometimes medication. Caught at 70 to 75 percent? You’re already in crisis management mode.

Senior bloodwork gives you a baseline. Even if everything comes back normal this year, that result is valuable because it tells your vet what normal looks like for your specific animal. Next year, a value that’s technically still within the reference range but has jumped significantly from your pet’s own baseline can be an early red flag. Population-wide reference ranges don’t tell the whole story. Your pet’s individual trend does.

What’s Actually in a Senior Panel

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A basic senior panel typically includes two components: a complete blood count (CBC) and a chemistry panel, sometimes with add-ons depending on your pet’s age, breed, and history.

The CBC looks at blood cells. Red blood cell counts tell you about anemia and hydration status. White blood cell counts signal infection, inflammation, or immune problems. Platelet counts matter for clotting.

The chemistry panel is where organ function lives. The main values your vet watches closely:

  • BUN and creatinine: kidney filtration markers. SDMA is a newer, more sensitive kidney marker that can flag problems even earlier, and many senior panels now include it.
  • ALT and ALP: liver enzymes. Elevated levels suggest liver stress or damage.
  • Glucose: screens for diabetes, which is common in older cats and dogs.
  • Total protein and albumin: reflect nutrition, liver function, and gastrointestinal health.
  • Electrolytes (sodium, potassium, chloride): critical for heart function and adrenal health.

Thyroid testing (T4) is often added for cats over 7 because hyperthyroidism is the most common hormonal disease in older cats and is very treatable when caught early. Dogs get thyroid testing too, though they tend toward hypothyroidism instead.

Some vets also recommend a urinalysis alongside bloodwork, because urine-specific gravity gives context to kidney values that blood tests alone can’t provide.

How Often Should Senior Pets Get Bloodwork Done

The general guideline, supported by AAHA hospital accreditation standards, is every six months for senior and geriatric pets. “Senior” typically starts at age 7 for dogs and cats, though large and giant breed dogs age faster and may be considered senior at 5 or 6.

I know twice-yearly testing sounds like a lot. But consider that six months in a dog’s life is roughly three to four human years. A lot can change.

If your pet has already been diagnosed with kidney disease, diabetes, hyperthyroidism, Cushing’s disease, or is on long-term medications like NSAIDs, steroids, or phenobarbital, your vet may want bloodwork every three months. Those drugs are hard on the liver and kidneys, and monitoring isn’t optional, it’s how you catch problems before they become emergencies.

For a pet with zero known issues and normal results? Annual bloodwork is reasonable until around age 10 or 11, when the every-six-months recommendation becomes more important.

Reading Your Pet’s Results: A Practical Breakdown

Your vet will go over results with you, but if you want to understand the printout yourself, here’s a plain-language guide to the most common findings.

ResultWhat It Might MeanNext Step
Elevated BUN/creatinineReduced kidney filtrationRecheck with urinalysis, consider renal diet
Elevated SDMA with normal creatinineEarly kidney stressMonitor closely, recheck in 3 months
High ALTLiver cell damage or stressInvestigate cause: medications, diet, hepatic disease
High ALPLiver, bone, or adrenal involvementContext matters: age, symptoms, other values
Low albuminPoor nutrition, liver disease, GI protein lossFurther workup needed
High glucosePossible diabetesConfirm with fructosamine test
High T4 (cats)HyperthyroidismTreatment discussion: medication, radioactive iodine, diet
Anemia (low RBC/HCT)Blood loss, chronic disease, bone marrow issueDepends on severity, recheck or further testing

Here’s what most people don’t realize: a single abnormal value rarely means disaster. Your vet looks at the whole picture, not one number in isolation. A mildly elevated ALT in an otherwise healthy 9-year-old dog who just had a fatty meal is very different from an elevated ALT in a dog who’s also lost weight and stopped eating.

How to Prepare for the Appointment and Get the Most From It

A little preparation makes a real difference, both for the accuracy of results and for your own peace of mind.

Before the appointment:

Fast your pet for 8 to 12 hours before bloodwork. Food can elevate glucose, triglycerides, and some liver enzymes, skewing results. Bring a list of every supplement, medication, or flea/tick preventative your pet takes, certain products affect bloodwork values. Note any changes you’ve observed at home: increased thirst, more frequent urination, changes in appetite or weight, unusual lethargy. Ask your vet if they plan to run an in-house panel or send it to an outside lab. Outside labs are often more comprehensive and accurate for subtle abnormalities.

At the appointment:

Ask for a printed copy of the results with reference ranges. Many clinics offer portal access now. Ask your vet to flag which values are outside your pet’s own historical baseline, not just outside the population reference range.

After results come back:

If something is abnormal, ask specifically: “What do we watch for at home?” and “What’s the timeline for the recheck?” Don’t leave without a clear next step.

Senior bloodwork isn’t about finding something wrong. It’s about knowing your pet well enough to catch something early, when there’s actually room to act. The pets I’ve seen do best in their final years are almost always the ones whose owners started paying close attention at 7 or 8, before there was any obvious reason to worry. That proactive window is worth protecting.

This article is for general informational purposes only and does not constitute veterinary advice. Pet health symptoms can have many causes and require professional evaluation. Always consult a licensed veterinarian for diagnosis and treatment specific to your pet.

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