Some dogs naturally have darker tongues.
According to the American Kennel Club, there are over 170 different dog breeds. As you might expect, with this many different breeds, dogs can come in all shapes and sizes. One notable trait is the appearance of a blue-black tongue. This can be due to any number of natural factors, though it can also be a symptom of illness.
Chow Chow
The Chow Chow's greatest claim to fame is its blue-black tongue, which makes many people think of this dog breed whenever they hear that a dog has a black tongue. The truth is, the Chow Chow is not the only dog breed with traits that cause blackness on the tongue, though it is one of the few that have completely black tongues. Interestingly, Chow Chows have pink tongues at birth, and the color darkens to blue-black by the tenth week.
Chinese Shar-Pei
The Chinese Shar-Pei is another breed of dog which can feature a completely blue-black tongue. Like the Chow Chow, the Chinese Shar-Pei is an ancient breed born with a pink tongue but later grows into a blue-black hue. Where these breeds obtained this trait is unknown, but the Chinese Shar-Pei have had blue-black tongues for as long as man has recorded it.
Semi-Blue-Black Tongues
Many breeds have the potential for puppies to develop pink tongues with blue-black spotting, and it doesn't always mean the dog is part Chow Chow or part Chinese Shar-Pei. For example, the Akita, the Australian Shepherd, the Bull Mastiff, the Cocker Spaniel, the Dalmatian, the German Shepherd, the Golden Retriever, the Irish Setter, the Labrador Retriever, the Newfoundland, the Pomeranian, the Rottweiler, the Shiba Inu and the SIberian Husky are all known to feature spotted tongues.
Black Tongue Illness
Like humans, dogs can suffer from illness that can lead to unnaturally black tongues. One of the main causes of such is malnutrition, in which the dog does not receive enough food for long periods of time. The primary reason the tongue goes black is due to niacin, a vitamin found in abundance in meat and meat byproducts. Consult your veterinarian if you believe your dog's black tongue is due to malnutrition or any other unnatural factors.
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