Can a smoky sclera be normal?

摘要

A The bulldog in your picture has more extensive scleral and episcleral pigmentation than we usually see in dogs, but it is normal. In dogs, the color of the sclera depends on the thickness of its stroma, the amount of pigment it contains, and the amount of fat in its outer boundary. The sclera is thicker near the limbus and thins toward the equator of the globe, making it appear whiter at the limbus in some individuals. However, it is common in dogs to have a large amount of limbal melanin that makes the limbus appear dark-brown or black. This pigment sometimes extends posteriorly for a few millimeters either around the entire limbus or may be particularly prominent laterally (Figure 1).