Dogs that have a black palate include the chow chow, the Pyrenean mountain dog, the Pyrenean shepherd and the Estrela mountain dog. The black palate is a genetic predisposition and is caused by darker skin pigments called melanin granules.
It is believed that melanin is the skin's natural response to ultraviolet radiation as it is able to dissipate nearly 99.9 percent of harmful UV rays. It is normal for these malinin areas inside the mouth to spread to the tongue or change shape as a dog matures. However, it is important to check these malinin areas regularly for bumps or raised surfaces. Normal malinin areas should be smooth and flat. Dogs with bumpy or raised malinin surfaces should be taken to a local veterinarian as soon as possible, as this may be a symptom of melanoma. It is important to also seek medical advice if a black tongue or gums is noticed in a breed of dog that is not predisposed to this physical trait.
This coloration could also be caused by cyanosis. Cyanosis is the darkening of the tongue, gums or palate due to insufficient oxygen circulation in the blood. Cyanosis can be a symptom of heart or respiratory disease. Any dog that is displaying symptoms of cyanosis should be evaluated immediately by a veterinarian.