My buddy may be dying

Just a question about Zeus. In your initial post you stated, "...he's not aggressive and gets along with the 4 other pups." But you didn't say anything about how Hobo gets along with the other dogs.
Knowing more about each dog may help with your rehoming efforts.

Sure OC, I have six altogether, male mini wiener dog about 10 lbs, a female wiener dog about 30 lbs, a male lab mix adolescent about 45 lbs, a female pitty about 60 lbs, and Hobo, male lab mix, about 60 to 65 lbs.
Zeus gets along fine, in fact he and the younger lab play run, i know he aggravates Zeus by the way he acts sometimes but never aggressively with any of the others. I guess it's just the big male/alpha male thing, and i think Hobo is the instigator because he was here first and thinks of Zeus invading his territory.
Zeus never barks first and usually ignores Hobo's barking, he's just calm and easy going.