Can Metamucil help my dog with soft stools and anal gland issues?

Metamucil may help some but I would keep her dose very small like around 1 teaspoon twice a day. You could also try to just add a small amount of canned plain pumpkin instead of the Metamucil. I would also consider trying to add in a probiotic and a sensitive stomach diet. I like a few different types of probiotics - propectalin, vetriscience probiotic chews, purina pro plan fortiflora or proviable. If you decide to switch her food, I would transition her from the old food to the new food very slowly over a 2 weeks period. If you haven't had her examined by a vet I would strongly recommend to have her looked at. There are a lot of things that can also cause loose stools like parasites, food sensitivities, inflammatory bowel disease, bacterial infections, giardia, and much more. Your vet will start with checking a fecal sample. I hope this helps!