After spending a lot of time around dogs, animal behaviorist Camille King started to notice a pattern: anxious canines appeared to become more gray in color over time. The gray hairs were particularly noticeable around the dogs' muzzles, giving them a grandfatherly whiskered look.
King, a Northern Illinois University (NIU) alumnus, investigated the matter further with a few colleagues and found out that she was not just imagining the connection. According to the new study, published in the journal Applied Animal Behavior Science, stress can cause dogs to go prematurely gray.
"It is not known if dogs go completely gray due to stress," King told Seeker. "I have seen in practice where dogs will have full gray muzzles and gray around the eyes."
RELATED: Your Grouchy Dog May Actually Have Autism
She, NIU professor Thomas Smith, animal behaviorist Peter Borchelt, and researcher Temple Grandin examined 400 dogs in Colorado at dog parks, dog shows, veterinary clinics and other venues. These observations, plus dog behavior questionnaires given to the pets' owners, revealed a link between a canine's documented anxious behavior and its likelihood of developing gray hairs between the ages of 1–4, when color changes due to natural aging would be unexpected.
Independent raters looked at photos of the dogs and judged the level of muzzle grayness for each. Their judgments corresponded with those of the scientists and dog owners.
As for humans, both genetics and environment can play into a dog's mood. A dog's environment is further complicated by the owner's physical and mental health.
"There have been some recent studies that suggest that dogs can pick up their owners' emotions," King, who has her own animal behavior practice in the Denver, Colorado, area explained.
RELATED: 'Claws' on a Cats' Tongue Work Like Velcro to Clean Fur
Extremely stressed out pets will even sometimes excessively lick their fur in certain places, causing bald patches to form. The ingested fur can cause further problems.
She says dog owners should think of muzzle graying-easier to see in dark-haired breeds-as a symptom for possible underlying issues.
"Anxiety and stress can present health risks for dogs, including risk of illness and shortened life expectancy," she said. "Premature muzzle grayness could serve as one of several markers for anxiety in young dogs. Addressing anxiety and impulsiveness issues at an early age can lead to a higher quality of life."
Dog owners who notice their pet is developing premature graying of the muzzle should consult with a veterinarian or professional dog behaviorist for screening. She said "effective treatments" are available to address canine stress, anxiety and impulsiveness.
A prior study also led by King, for example, found that pressure wraps called "Thundershirts" can lower canine heart rate levels and other symptoms of stress in anxious dogs. Presumably these garments, and other treatments, could also help to preserve a dog's youthful looks for as long as possible.
WATCH: Dogs Have Feelings, Too