Christa I'm thinking it's the poo thats changed and not the litter. I use Fresh Step and I haven't noticed any difference in it lately. Maybe you just got a bad batch? It could also be because little Brodie is growing up! Are you sure it's not a stonger urine smell? I know Brodie is still really young but some of those little boys grow up quicker than others. Nobody has any runny poo do they?