|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
A dun horse is used to describe any bay, black, or chestnut-based horse affected by the dilution gene that brightens both red and black pigments in its coat colour, lightening the base body coat and suppressing the underlying base colour to the mane, tail, legs, and primitive markings. The classic dun is a grey-gold or tan, characterised by a body colour ranging from sandy yellow to reddish brown.