What Causes a Dog's Hair to Turn White?

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A dog's hair may turn white because of an underlying illness or stress or as a natural part of getting older. Like humans, dogs' hair normally turns white or gray when they reach a certain age. If you see dog whiskers turning white much earlier than expected, the cause of it could be unrelated to age. A vet might offer some clarification about what's causing premature graying in your dog.

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A dog's hair may turn white from age or illness.
Image Credit: Akchamczuk/iStock/GettyImages

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Why hair turns white

Melanin gives hair its pigment, and it provides protection from the sun's harmful UV rays. If the hair follicle produces more melanin, the hair grows in with more pigment and has a richer color. If it produces less melanin, the hair contains less pigment and may appear gray. In a hair follicle that produces no melanin, white hair grows. Genetics determine how much melanin a hair follicle produces, but other factors, such as hormones, inflammation, UV rays, age, and pigment disorders, can affect how much melanin your dog's hair contains.

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Age and genetics

Dog whiskers turning white is a common sign of aging, and it usually means a dog has entered his senior years. Genetics is the main factor that determines exactly when hair starts to turn gray as a result of aging. Once hair starts to turn gray, those hairs won't return to their natural color.

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At what age do dogs get a gray muzzle? Dogs usually have gray in their muzzle by around 5 to 7 years old. Giant breeds (over 91 pounds) tend to age faster than smaller breeds and become senior by the time they're 5 years old. Small and medium-size breeds become senior at 7 years old.

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At what age do Yorkies turn silver? A Yorkie's coat changes over time, usually starting out predominantly black and developing more of a tan color in adulthood. A senior Yorkie (8 to 10 years old) might get a few extra silver hairs; however, Yorkies never turn completely gray.

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Stress and anxiety

A dog's premature graying hair could be caused by stress. Dogs as young as 1 year old have been seen with gray muzzles, and many of them have something in common. Younger dogs with prematurely gray hair often have poor impulse control, experience separation anxiety, or are fearful of people, animals, or sounds.

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According to a study published in Applied Animal Behaviour Science, anxiety and impulsivity are strongly associated with premature graying in dogs between 2 and 4 years old. These findings are similar to what has been observed in humans. If the effects of stress on graying hair in dogs are consistent with humans, stress-related graying in dogs might return to its original color if the stress is eliminated.

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Underlying health issues

Certain health issues can cause hair to turn white prematurely. The thyroid gland affects many bodily functions, such as temperature, metabolism, shedding, heart rate, and digestion. A dog with an underactive thyroid gland has a condition called hypothyroidism. Since the thyroid gland affects nearly every organ, an impairment can cause symptoms including weight gain, skin infections, and premature graying. With treatment, your dog's hair will likely return to its original color. If you suspect that your dog has hypothyroidism, take him to the vet.

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