I use Bactaquin for Katie I originally got it from Dr. Fosters and Smith free when I purchased Cosequin, but now I get it from Costco.com. At the moment, its no longer available there. There are many other effective probiotics to buy that are more cost effective than FortiFlora. I've read on this forum that Dogzymes Probiotics Max are good.
Nature's Farmacy - Store - Product Details Pet Probiotics | Probiotics for Dogs & Cats - Mercola.com