It's also a good preventative any time your dog (or you) has to take antibiotics. Antibiotics not only kill the bad bacteria, they will also kill some of the beneficial bacteria. The probiotics will restore or maintain the proper balance in the intestinal tract.
About 40 years ago, my aunt had a friend that was prescribed antibiotics, and she foolishly thought that if taking it as prescribed was going to cure her, why not just take them all at once? It put her in the hospital and she almost didn't make it.
There is another way to restore balance in the gut .... fecal transplants:
Fecal transplants may stall as FDA cracks down on docs - NBC News.com