Blood Test May Predict Lifespan in Dogs, Cats, and Horses

A protein marker that helps doctors understand brain aging in humans turns out to work just as well in measuring how fast our pets are growing old.

Researchers at Germany's DZNE and the University of Tübingen found that neurofilament light chain (NfL), a protein released when brain cells age or become damaged, appears in measurable amounts in the blood of mice, cats, dogs, and horses. Just like in humans, the levels rise with age.

The discovery happened almost by accident. Professor Mathias Jucker's team had been studying NfL in human dementia patients when they wondered if the same marker might appear in animals. They tested samples from over 50 species, including rabbits, lions, monkeys, elephants, and even some reptiles and birds.

The protein showed up in all mammals tested. A few birds and reptiles, including a crocodile and parrot, also carried detectable levels.

But the real breakthrough came when Dr. Carina Bergmann tracked 44 older mice over four months. The animals with slowly rising NfL levels lived significantly longer than those whose levels climbed quickly. This mirrors what scientists already knew about elderly humans, where NfL concentration links to mortality risk.

The finding suggests veterinarians could eventually use a simple blood test to estimate how much healthy time a pet has left. That knowledge could guide treatment decisions and help owners plan better care for aging animals.

The Bright Side

This research shows how breakthroughs in one field can unlock unexpected benefits elsewhere. Tools developed to fight devastating human diseases like Alzheimer's and ALS are now opening doors in veterinary medicine.

For pet owners, the potential is deeply personal. Cats and dogs age at different rates depending on breed, size, and individual health. A blood test that reveals biological age, not just calendar age, could help identify problems early or confirm that an older pet still has good years ahead.

The test could also transform care for horses, zoo animals, and endangered species by giving caretakers better information about health and longevity. Zoos could use it to make breeding decisions or adjust care plans for aging animals.

The research team collaborated with Stuttgart Zoo, the University of Zurich, and veterinary labs to gather samples across such a wide range of species. That kind of teamwork shows what becomes possible when human medicine and animal care experts share knowledge.

A simple blood draw could soon tell us what we've always wanted to know: how much time we have left with the animals we love, and how to make those years count.