Purina Life Span Study data used to test biological age tool in dogs

In research published in GeroScience, Nestlé Research scientists applied a bloodwork-based biological age algorithm to data from the well-known Purina Life Span Study. The analysis found that lean-fed dogs had a significantly lower biological age relative to chronological age after 7 years of life, a gap that appeared years before survival differed between the groups.¹

The Purina Life Span Study followed 48 Labrador retrievers from 1987 to 2001.² Dogs fed to stay lean throughout life lived a median of 1.8 years longer than littermates fed as controls.^2,3 The Purina Institute marked the study’s 25th anniversary this month and describes the work as the first lifelong dietary study in dogs.⁴

How the aging tool works

The Nestlé Research team built and validated the algorithm using bloodwork and health records collected over more than 12 years from 829 dogs at a pet care center. The algorithm combines 10 values from a standard complete blood count and serum chemistry panel.¹

Each additional year by which a dog’s estimated biological age exceeded its chronological age was associated with a 75% higher risk of death. In nearly half of the dogs whose biological age ran more than 1 year ahead, no more than 1 individual marker fell outside its reference range.¹

The researchers applied a modified version of the algorithm to the Life Span Study’s blood count and serum chemistry data, because 2 of the algorithm’s markers were missing from the older dataset.¹

The authors wrote that this type of tool does not qualify as a diagnostic test by itself. Instead, they proposed using the tool to complement existing tests by flagging when a deeper health assessment may be needed.¹

All of the paper’s authors are employees of Nestlé Research, which funded the work. The authors disclosed that patents related to the work have been filed.¹

About the original study

In the Life Span Study, funded by Ralston Purina—now Nestlé Purina—investigators paired the 48 Labrador retrievers from 7 litters by sex and body weight at 6 weeks of age. Dogs in each pair were randomly assigned to a control group or a lean-fed group. Feeding began at 8 weeks of age.²

All dogs ate the same diet, but the amount differed. Each lean-fed dog received 75% of the food its control-fed partner had eaten the previous day.² Control dogs initially ate free choice. When the dogs were 3.25 years old, investigators fixed the control dogs’ portions to prevent serious obesity.²

From 6 to 12 years of age, control-fed dogs averaged a body condition score of 6.7 on a 9-point scale. Lean-fed dogs averaged 4.6.²

Lean-fed dogs went longer before needing long-term treatment for a chronic condition. The median age at which treatment began was 12.0 years for lean-fed dogs, compared with 9.9 years for control-fed dogs.²

The Life Span Study investigators highlighted osteoarthritis among the late-life diseases that were delayed in lean-fed dogs. At 8 years of age, 10% of lean-fed dogs had osteoarthritis in 2 or more joint types, compared with 77% of control-fed dogs. By the end of the study, 83% of control-fed dogs had radiographic evidence of hip osteoarthritis. That figure was 50% for lean-fed dogs.²

The investigators noted that the diseases leading to death were generally similar between the 2 groups. The main difference was timing.²

Bringing it to the exam room

The Purina Institute said routine body condition scoring and nutrition counseling can make healthy weight part of preventive care. The institute pointed to an ideal score of 4 to 5 on a 9-point scale for dogs.⁴

Julie A. Churchill, DVM, PhD, DACVIM (Nutrition), of the University of Minnesota College of Veterinary Medicine, said in the Purina Institute’s announcement that she integrates the study’s findings and talks about them with pet owners every day.⁴

“The message is simple but powerful: feeding pets to maintain a fit and lean condition supports longer, healthier lives,” Churchill said.

References

1. Herzig S, Zollinger A, Texari L, et al. A biological age based on common clinical markers predicts health trajectory and mortality risk in dogs. GeroScience. 2025;47(1):45-59. doi:10.1007/s11357-024-01352-4
2. Lawler DF, Larson BT, Ballam JM, et al. Diet restriction and ageing in the dog: major observations over two decades. Br J Nutr. 2008;99(4):793-805. doi:10.1017/S0007114507871686
3. Kealy RD, Lawler DF, Ballam JM, et al. Effects of diet restriction on life span and age-related changes in dogs. J Am Vet Med Assoc. 2002;220(9):1315-1320. doi:10.2460/javma.2002.220.1315
4. 25 years later, landmark Purina Life Span Study still shapes healthy weight conversations for dogs. News release. Purina Institute. October 12, 2026. Accessed October 16, 2026. https://www.prnewswire.com/news-releases/25-years-later-landmark-purina-life-span-study-still-shapes-healthy-weight-conversations-for-dogs-302905985.html