What Causes Purple Pigment in a Dog's Tongue?

The chow chow and shar pei are two dog breeds where purplish-black tongue color is normal.
Photodisc/Photodisc/Getty Images

When you bring home a puppy with a bright pink tongue, you may find yourself startled when that tongue begins to develop purple, blue or black pigmented spots or turns completely dark. Two breeds, the chow chow and the shar pei, are born with pink tongues that gradually turn completely purplish due to increased pigmentation. The cause of this excess pigmentation is unknown but can occur in mixed breeds as well as show breeds, which can develop spots. Beware that medical conditions can contribute to color changes on the tongue.

Breeds Prone to Purple Spots

When you bring home your Labrador retriever and he suddenly develops purple spots on his tongue, this doesn’t mean he is mixed with a chow. Certain breeds develop spots of excess pigmentation similar to how humans are born with birthmarks. In most cases, your dog probably has darker spots on other areas of his body as well. There are more than 30 breeds known to have tongue spots including German shepherds, collies, rottweilers, Irish setters, cocker spaniels and Dalmatians.

Other Possible Medical Reasons

While excess pigmentation does not cause medical problems, purple, blue and black discoloration of the tongue can be a sign of health problems in a dog with a normally pink tongue. Black tongue is a nutritional deficiency caused by too little niacin in the diet. Cyanosis causes a bluish tint to the tongue and is due to decreased oxygen in the blood.