Overview
- Researchers analyzed 1,640 blood methylation profiles from 894 pet dogs to build an epigenetic clock that estimates biological age with a median error under one year.
- The study found that larger breeds have accelerated epigenetic aging in blood compared with smaller breeds, driven by faster loss of DNA methylation in regions that silence transposable elements.
- LINE1 elements, a common type of 'jumping gene,' showed particularly rapid methylation loss in large dogs, a change that can raise genomic instability and is linked to cancer and age-related disease.
- Dogs whose epigenetic age exceeded their calendar age faced higher near-term mortality, while a separate, developing sex-linked signal appeared mainly on the X chromosome and needs further study.
- Authors say selective breeding for rapid growth likely created late-life molecular costs and that experimental work is needed to test whether slowing epigenetic aging could extend healthy lifespan in large breeds.