Newer kidney tests spot early changes in senior dogs that look healthy

If you share your home with one of the many senior dogs out there, here is good news. Vets now have newer tests that pick up kidney changes before the usual blood work does.

In a new study of healthy older dogs, these tests found early kidney changes in dogs whose standard results looked completely normal. That means your dog’s kidneys can be checked more closely, and early is the best time to know.

How the study worked

Researchers looked at 61 neutered older dogs with no signs of illness and no other abnormal lab results. They measured cystatin C in the blood and a urine marker called the NAG index, then compared them with standard creatinine results. The work was a cross-sectional study, meaning a snapshot in time, published Aug. 28, 2026, in Veterinary Sciences. Because cystatin C helped sort the dogs into groups and the team did not directly measure kidney filtration, the results show a clear pattern that future follow-up studies will confirm.

What they found

Of the 61 dogs, 17 had at least one elevated newer marker even though their creatinine was normal. That is 27.9% of the dogs, or more than a quarter.

All 17 of those dogs also had normal urea, another standard blood test. So the changes showed up before the usual tests turned abnormal. Cystatin C found most of them.

The urine NAG index, which is a sign of stress on the kidney’s tiny filtering tubes, was elevated in 6 of the 17 dogs, or 35.3%. SDMA, another kidney blood test vets use, was elevated in none of the 17.

In plain words: dogs that looked fine on the standard tests had something worth noticing, and the newer tests were the ones that noticed it.

Why can a normal result miss something?

Creatinine is a waste product that your dog’s blood carries to the kidneys. How much of it shows up depends partly on muscle. As dogs age, they lose muscle, so a creatinine number can look reassuring when it should not.

Cystatin C is a protein that is less affected by muscle mass. That is why it works well as a second look in older and thinner dogs.

The takeaway for you: a normal result on one test is a good sign, and pairing it with other tests gives a fuller picture.

What you can do today

Check when your dog last had senior blood and urine tests. If your dog is 8 or older and it has been more than a year, call your vet’s office and book a senior checkup. When you call, ask which kidney tests the clinic can run.

At home, keep fresh water out at all times. Keep an eye on how much your dog drinks and pees, plus weight and appetite, and mention any change at the visit. A short note on your phone makes that easy.