What is wrong with my 10 yr old Sheltie He has recently developed a liquid-like black stool ring on his anus. I clean it off but it just comes back like it's oozing out of his rectum or something?

I would strongly recommend taking your Sheltie to a veterinarian. Black discoloration to the stool typically means there is an intestinal bleed somewhere that needs to be addressed. The cause of the bleeding could be anything from a stomach ulcer to a laceration in the intestines to cancer.