Large dogs accumulate age markers faster than small breeds

Large dogs show age-related molecular changes faster than smaller breeds, according to a US study reported by ERR.

Researchers analysed genetic data from nearly 900 dogs representing about 120 breeds. They examined chemical markers attached to DNA, known as methyl groups, whose loss or addition is considered a biological sign of ageing.

The study found that large dogs accumulated these epigenetic changes significantly faster than small dogs. Changes also occurred faster in males than females, even when the male dogs had been neutered at a young age.

Based on the findings, the researchers developed a biological clock that can estimate a dog’s age to within one year. Dogs whose epigenetic age was higher than their chronological age faced a greater risk of dying in the following two years.

The researchers said mobile sections of DNA known as jumping genes may help explain the findings. Methyl groups normally keep these sections in place, preventing them from interfering with other genes. In large dogs, the markers may be lost faster with age, potentially allowing jumping genes to move and disrupt the work of important genes.

The loss of these markers and the release of jumping genes are linked to inflammation and faster ageing. Researchers suggested that females may age more slowly because their additional copy of the X chromosome could help balance age-related epigenetic changes. The findings were published in the journal Science.