Indeed, people have been using colloidal silver on their “Parvo puppies” (and grown dogs with Parvo, as well) for many years, and usually to great success, as this video attests.
The key seems to be to keep the puppies well hydrated, because they don’t like to eat or drink when they have Parvovirus.
So Pedialyte for animals (available from the vet or pet store) or some other hydrating fluid is given orally throughout the day, using either an eyedropper (for puppies), or for larger dogs a large syringe, without the needle, of course.
Some people recommend pouring a capsule full of Lactobacillus acidophilus (beneficial digestive microorganism available at any health food store) into the Pedialyte before administering it to the dog, as the beneficial microbes will compete for space in the puppies tummy with the Parvovirus (i.e., called “competitive inhibition”) and also help prevent some of the diarrhea, as well as the damage to the stomach lining done by the virus.
Some people also recommend trying to feed the dogs with baby food (well strained chicken, for example) in order to get some nourishment into them. Others recommend a commercial product called Nutristat (available online), which is a gel-like paste containing nutrients, electrolytes, fats and protein to nourish the dog while eating is problematic due to the virus.
Finally, colloidal silver is also administered orally, multiple times throughout the day until the dog’s appetite returns and Parvo symptoms are gone.
See my video here on how to administer colloidal silver or other liquids, orally to dogs: http://thesilveredge.com/video-pets-and-colloidal-silver.shtml