Simply stated... ceramic tile floor with medium gray grout, one fast little male chihuahua who just had to mark his territory indoors, and now some areas are darker grout from pee stain! I want to get rid of stain but keep chihuahua.

Have you tried bleaching it? I mean as long as it was cleaned right away, it shouldn't have left a stain. I have ceramic, and a dog who suffers from terrible separation anxiety. One place was darkened, but I used water and bleach and a tooth brush and it looks normal now. Just be careful with the bleach on the ceramic.

Thanks Aurora_Bell! I'll try that next.

Bleach may work temporarily but if it keeps happening... White vinegar usually cleans it up. If not then make a paste with it and baking soda and let it sit over night. You will literally see the baking soda turn yellow from lifting the pee. Then wipe it up with hot water. Then wash with dawn dish soap and hot water to get rid of the vinegar smell. Trust me. Ive had dogs for years and spent hundreds on products. This is the only thing that works on everything from linoleum, to wood, to porcelin to tile.