Surgery & Hair Loss

by Girelk
(Utah)

Almost 1 1/2 years ago my pom had surgery on both of his back knees. The hair never grew back and lately his skin has been turning a dark color.

I did some reading and at first thought it might be black skin disease but he doesn't seem to have any sores and he doesn't have a bad smell, which from what I have read are two of the symptoms.

Any idea what it might be or how I can fix it?