For dogs – any changes can go overlooked for days and even weeks at a time, thanks to the coat covering their bodies. If one day you were cuddling with your dog and came across some purple patches on its belly, you would be alarmed as any fur parent will.
In a nutshell, hyperpigmentation is the skin turning into a darker coloring. In your doggie’s case, its belly is usually milky white with fur, but it turns purple, blue, and sometimes even black because of hyperpigmentation.
Hyperpigmentation (Acanthosis Nigricans) is classified into two types – primary and secondary. Primary hyperpigmentation is not curable. It is more of a cosmetic concern, and you can consider it as a beauty mark on your dog, just like you would for freckles and birthmarks.