People use Metamucil all the time to help treat constipation and diarrhea, or just to add some much-needed fiber to their diets. The fiber supplement can be useful to your pets, too. If your pet comes down with an unfortunate case of the squirts, a small amount — 1/8 to 1/4 of a teaspoon — of Metamucil can help bulk up stools to treat a mild bout of diarrhea. The same treatment can also help with constipation. Ain’t fiber a miracle? (PetMD)