German shepherd dogs are known for their intelligence, loyalty and bravery as much as for their majestic appearance. Not much consideration is usually given to the appearance of a shepherd's tongue, however, unless it looks unusual, such as having black spots. Such spots bring up questions about a German shepherds lineage.
Indication of Breed
It is a common misconception that black spots on a dog's tongue mean he must be mixed with chow chow, a breed known for having a completely black tongue. Individuals of many breeds of dogs can have spots on their tongues but are completely unrelated to the chow chow. Black spots on a German shepherd's tongue are not an indication that he is mixed with another breed. It is not uncommon for purebred German shepherds to have a few tongue spots. On the other hand, German shepherd mixes can also have the spots, which means that you can't use them to determine whether or not a particular dog is purebred or a mix.
Melanin
Melanin, the pigment that causes colored spots on the skin, can create black spots on the tongue. This is normal and natural, similar to a birthmark. It is often an extension of dark coloring on a dog's muzzle. The number, size and shape of the spots are determined by genetics, although a dog with spots on his tongue may not necessarily have offspring with spots, and two dogs without spots may produce offspring with spots.
Cancer
Black spots caused by melanin are not unusual. They are present at birth and remain essentially the same shape and size throughout the dog's life. Black spots that suddenly appear on an older dog's tongue, or that appear raised or textured, may signify cancer. If your dog's pink tongue is suddenly discolored with spots, or if existing spots change in size, shape or texture, call your veterinarian.
Other Causes
Certain illnesses can cause tongue discoloration that may appear similar to black spots. These include kidney disease; low blood oxygen, often as a result of heart or lung problems; niacin deficiency; and oral ulcers. Like cancerous growths, these spots appear suddenly -- they were not present at birth. Have your vet check any change in your dog's tongue, including turning a purple-black color.