I think the Soverign Silver will be just fine. It has small particle size. Get the dropper bottle and Drip it into the cats mouth. Then when the Silver Puppy comes the cat will be ready to drink more and you can reuse the bottle.
Any Silver is better than no Silver. Hurry before your cat falls over for the last time.
2 ounces of 10 ppm Soverign are Silver is $12! My Silver Puppy makes gallons for nothing except for the electricity and distilled water. The electrodes last forever.
If the Silver doesn't work your cat may have worms or something but I think the silver will always help if not cure.