rx vitamins for pets - phos-bind 35 gm powder mardog rx vitamins phos-bind contains 100% pure and finely ground, usp grade aluminum hydroxide. the powdery form of the aluminium hydroxide is highly palatable when blended with a pet's meal. phos-bind will complex with dietary phosphorus in the bowel to help support the normal function and health of the kidney. veterinary nephrologists and internists prefer the single ingredient found in phos-bind over other products when treating and caring for kidney patients.