History records that something remarkable happened to Marie Antoinette (1755-1793), the ill-fated queen of France. The night before her jailers walked her to the guillotine her hair allegedly turned white. She is not the only person whose hair lost its color because of a major stressful event. According to historical reports, Sir Thomas More (1478-1535) also had his hair suddenly turn white in the tower of London. This was the night before his execution by King Henry VIII for refusing to sign the act that declared Henry to be the Supreme Head of the Church Of England. More modern accounts tell of survivors of bombing attacks in World War II whose hair turned white as a result of the anxiety they had experienced. Furthermore an examination of "before and after" photographs of United States presidents shows a highly visible increase in the amount of gray hair by the end of a four-year term. Some scientists suggest that this is a consequence of the stresses experienced in that office.
Whether we are stressed or not we all expect our hair to begin to turn gray as we age. At the age of 45 for 50 years it is expected that most of us will have visible graying. With increasing age dogs also begin to turn gray and this lighter hair appears first on the dog's muzzle and face. This graying is usually quite noticeable by the time the dog is 7 or 8 years old.
Of course there is a lot of variability in the age when a person's hair begins to turn gray and the same is true for dogs. Some dogs can show graying on their muzzle as an early as 1 or 2 years of age. Genetics clearly plays a role, but other factors, including stress also contribute.
Hair color comes from melanin, a pigment which is produced in each hair follicle. There are two hypotheses as to how graying comes about. The first is that aging wears down your DNA, somehow inhibiting the production of the cells called melanocytes that produce melanin. The second hypothesis says that your hair gets bleached from within because hydrogen peroxide is also produced in small amounts in the follicles. Normally this bleaching compound is kept in check by another enzyme called catalase but eventually this enzyme ceases to be produced.
Scientists are still not clear how stress might prematurely trigger either of these processes, however in 2011 a team led by Nobel prize winner Robert Lefkowitz offered a clue. It has to do with exposure to stress related hormones, specifically the catecholamines (such as adrenaline and noradrenaline). If such exposure goes on for a prolonged time it has many negative effects, and these can reach all the way down to the level to where they affect the operation of the genes that control hair pigment. This can cause premature graying in people, and some new data suggests that the same stress factors can also cause your dog to gray earlier.
Recent research by a team headed by Camille King of the Canine Education Center in Aurora, Colorado, shows that anxiety and a personality factor called impulsivity can predict premature graying in dogs. Their findings are reported in the journal Applied Animal Behaviour Science*. This was a fairly large study involving 400 dogs 1 to 4 years of age. Although the study included a variety of different breeds, the researchers had to exclude dogs whose hair color was too light to allow them to see the presence or absence of gray muzzle hair.
Photographs were taken of the head of each dog and later independent scorers determined how much graying had occurred on the dog's face, and how far the gray hair crept along the muzzle line. The dog's owners were also given a questionnaire which included a set of items to determine the typical anxiety and impulsivity levels in their dogs. Anxiety was defined as a reaction to a possible or imagined danger and its symptoms include restlessness, fearfulness, stress whining, cringing to avoid being touched, and submissive urination. Impulsivity is a personality trait which looks a lot like hyperactivity in dogs. Dogs that are high on this trait are distractible, hard to calm, have difficulty maintaining a stay position, are endlessly barking and jumping up on people, chasing and so forth.
Although the researchers used some high-powered statistical regression analyses on the data, the basic findings are quite clear. To begin with, as you might expect, older animals were more likely to show graying of the hair on the face. One little surprise here was the fact that female dogs tended to show more graying than males.
When the researchers turned to the critical variables they found that the more anxious and impulsive a dog is, the more likely it is to show premature graying of the hair of the face. The most graying was found on dogs which were fearful of loud noises and unfamiliar people or unfamiliar animals.
The neat thing about these findings is that a dog which is showing premature graying is essentially hanging out a flag which indicates that he is under stress and may have impulse control problems. The researchers describe it this way:
"One practical implication of the findings of this study involves the possibility of using observations of muzzle grayness in a diagnostic manner to address anxiety, impulsivity, or fear issues. That is, if dog professionals (veterinarians, applied behaviorists, dog trainers, etc.) are able to note premature graying in their assessments and or training, then these dogs might be assessed more thoroughly for anxiety/impulsivity/fear problems and, if necessary, started on behavior modification programs earlier in their developmental life stages."
In other words, if a young dog is already beginning to show graying on its muzzle, then it may be time to start thinking about teaching the dog some coping skills and behavior control.
Stanley Coren is the author of many books including: Gods, Ghosts and Black Dogs; The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome
Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission
* Data from: Camille King, Thomas J. Smith, Temple Grandin & Peter Borchelt (2016). Anxiety and impulsivity: Factors associated with premature graying in young dogs. Applied Animal Behaviour Science, 185, 78-85.