A.The probiotic I prefer over all others on the market are those composed of soil organisms. Initially, I started using Primal Defense by Garden of Life. While others are now becoming available, it is the original and the one I still prefer. As far as topical treatments for yeast go, a product named Malaseb might help; consult with your veterinarian. The true way to know which vitamin C to chose would be determined by blood results and by looking at the enzymes that reference acid and base balance.