The present study examined the association of anxiety and impulsivity with premature muzzle grayness among young dogs. A sample of 400 dogs, ages 1–4 years was obtained at dog parks, shows, veterinary clinics, and other venues. Each dog was photographed and the degree of muzzle grayness was rated on an ordinal scale ranging from “no gray” to “full gray.” White or pale colored dogs were dropped from the study because it was impossible to determine degree of grayness. Each owner filled out a questionnaire assessing the constructs of anxiety and impulsivity, as well as other behaviors and characteristics. To prevent response bias, owners were told that the purpose of the study involved dog lifestyle. Distractor items were added to the survey to prevent the owner from guessing the purpose of the survey. Examples of survey items indicating anxiety included: destruction when left alone; hair loss on vet exam or being in a new place; and cringes/cowers in response to groups of people. Examples of survey items indicating impulsivity included: jumping on people, inability to calm, loss of focus, hyperactivity after exercise. In our sample of young dogs, latent variable regression showed that the extent of muzzle grayness was significantly and positively predicted by anxiety (p = 0.005) and impulsivity (p < 0.001). Dog size, spay/neuter status, or medical problems did not predict extent of muzzle grayness. Fear responses to loud noise, unfamiliar animals and people were associated with increased grayness. Ordinal regression analysis showed that muzzle grayness was significantly predicted by fear of loud noises (p = 0.001), unfamiliar animals (p = 0.031), and unfamiliar people (p < 0.001). Premature graying in young dogs may be a possible indicator of anxiety, fear or impulsivity issues in dogs under four years of age.