I have a ten year old turkish van, about 20lbs and I swear he urinates acid! No matter what sort of litter I buy- multiple cat ( I do have two cats, also a little tabby girl), clumping, any kind at all, once he uses it, it's useless! I can change it at night, and the next morning, you'd swear it's been there for days, and desperately needs changing (So then he voices his displeasure by doing his business next to the litter box.)
Please, is there anything I can do? I'm reaching a point of maybe needing to rehome my old tom before I move in August, but I'd rather keep him.