Can dragons shapeshift

In several stories, dragons have been known to shapeshift. This trend is more prominent in Asian mythology; as it was a natural ability of gods, and demi-divine creatures, also known as youkai in Japan, such as a kitusne (multi-tailed fox) or tanuki (a native creature of Japan believed to have magic powers). Now, while I have Japan several times, dragon myth extends all over Asia. One well known dragon that shape-shifted was the dragon in the Chinese story, "Journey to the West". In the beginning of the story, a monk on a pilgrimage has his horse devoured by a dragon prince. As punishment, he has to take the horse's place. Interestingly enough, the fact that the horse is actually a dragon seems to be a forgotten fact throughout the story.

As an interesting contrast, in Western literature, it is often humans (or a close relation thereof) that take the shape of dragons instead, such as Fafnir: dwarvin prince driven to protect gold. If it occurs at all. However, there is one story of Melusine. It is a French tale of a woman of the same name. A nobleman falls in love with her, and, depending upon the version, the woman either asks that her husband leaves her alone for one day out of the week, or does not go to church. Either way, the husband finds out that she is a dragon and she leaves him. One version I read ended on the note that should a member of the supposed family die, a dragon can be seen flying overhead in grief.

Now, the idea of shapeshifting dragons has been greatly popularized, especially in the role-playing game Dungeons and Dragons and several books. Typically, this ability is explained via magic or an innate ability of the dragon itself. Whatever the reason, it is a well accepted ability of the dragon, provided there is an explanation of the ability at all.