A system for detecting protein in mammalian urine is disclosed herein. Phloxine B buffered between pH 2-2.5 undergoes a color change from colorless to red in the presence of protein. Disclosed herein are animal litter compositions and additives comprising Phloxine B and a protein-sequestering agent buffered at a pH below about 3 which detect the presence of protein at levels indicative of ill-health in feline urine.