I think I've figured out a part of the problem. Was feeding them supplements also feeding the candida in the intestines? Maybe. Some sites think so.
I'm thinking that the problem with the supplements only started after the Full Moon (or more correctly after the Last Quarter) - which is probably when the intestinal yeast and bacteria expel their toxins? That's the time period in which two gangrenous dogs died and Icy went down in energy suddenly.
Would it help if I gave them garlic and other anti-yeast stuff during this period to detox? I've got to look into that. I did give them all the sulfates - Mag sulph, Copper Sulph, Zinc Sulph hoping the sulphate part would do the detoxing, but maybe it doesn't work that way. Maybe we should use organosulfs like DMSO, MSM, garlic to do that job.