Stress turning your hair grey? You may not be the only one.
A new wide-ranging study of dogs has found that anxiety may have the same effect on our four-legged friends.
A survey of more than 400 canines found that going grey around the muzzle was not only a sign of old age — but stress.
Scientists who ran the study, published in the journal Applied Animal Behaviour Science, said they had long expected this to be the case.
The research involved visiting dog homes and veterinary clinics in Colorado, U.S.
Owners were asked 42 questions about the lifestyle, health, behaviour and appearance of their animals, including whether dogs destroyed things when left alone and if they cowered when in groups of people.
The study excluded fair-haired dogs, where it would be difficult to identify grey hairs.
Lead researcher Camille King said: “Based on my years of experience observing and working with dogs, I’ve long had a suspicion that dogs with higher levels of anxiety and impulsiveness also show increased muzzle greyness.”
Professor Thomas Smith, from the Northern Illinois University, said: “At first I was really quite sceptical of the hypothesis, however when we analysed the data the results were striking.”
In humans, grey hair is caused by the depletion of melanin, which is responsible for the pigment in hair and skin, something that occurs as we get older.
However, whether or not stress causes humans to go grey is still up for debate.
Stress hormones appear to be involved in the movement of melanocyte stem cells — which produces melanin — from hair follicles to the skin, but there are many factors involved.
Earlier this year scientists at University College London said they had identified the gene responsible for grey hairs.