Stress makes dogs go grey as well as humans - new study
Going grey due to stress and anxiety is an inseparable part of being human, but new research suggests we are not alone.
A pioneering study of dogs found has found that the famously loyal four-legged animals may be suffering exactly the same fate.
A survey of more than 400 canines established that going grey around the mouth and face was not only a sign of distinguished old age.
In just the same way humans with stressful jobs acquire the “salt and pepper” look at a younger age, dogs who had undergone a harder life were found to have acquired grey hairs earlier than those with a more care-free existence.
Scientists involved in the study, published in the journal Applied Animal Behaviour Science, said they had long suspected stress manifested itself in this way, but that finding evidence for the theory had been challenging.
The research involved visiting dog homes and veterinary clinics across the state of Colorado.
Owners were asked 42 questions about the lifestyle, health, behaviour and appearance of their animals.
This included whether dogs destroyed things when left alone, if they cowered when in groups of people and if they suffered hair loss.
Impulsivity, such as how often a dog jumped up on people, was also measured.
The researchers also took a mug shot of each dog and graded each on a scale - they excluded light coloured dogs as it was harder to tell if they were grey.
The results showed that dogs which were more impulsive and more anxious were greyer than those who were calmer.
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.”
Greyness had nothing to do with a dog’s size, whether it had been spayed or neutered and any medical issues the pet had been through.
However dogs that were scared of loud noises and animals they did not know were more likely to be grey as they appeared to have a nervous disposition.
Lead researcher Camille King, who runs a veterinary practice in Denver, 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.”
He added that there was hope for owners of anxiety-prone animals, as they could enroll their dogs on special training programmes to help them deal with stress better.
In humans, grey hair is caused by the depletion of melanin, which is responsible for the pigment in hair, skin and eyes, making blondes lighter and brunettes darker.
Genes and health play the most prominent role in what age and at what speed people’s hair colour begins to change.
The average age for women to start greying is thought to be about 35, while men tend to start earlier, around 30, although grey hairs can make their first appearance in teenage years or not until the age of 50.
Earlier this year scientists at University College London announced they had identified the gene responsible for grey hairs.
They said they were confident the discovery would make it possible to create a drug to switch it off.
