Abstract: An improved litter for the accumulation of animal urine comprises a cellulosic base material which is impregnated with a pH-indicating solution to provide a visually detectable color transition at a particular pH level. Cellulosic material such as wastepaper, newsprint, cardboard, etc. can be used to form cellulosic particles that are light, absorbent, and relatively dust-free. In the preferred embodiment, cellulosic particles are impregnated with a pH indicator such as litmus which will undergo a color transition upon contact with animal urine, thus providing an indication that bacteria may be present. The color of the litter is changed from blue to red at each location of animal urination. This improved pH-sensitive litter, therefore, provides a cost-effective and environmentally safe means for pet owners to determine when animal litter needs to be changed.