Old topic, but sharing experinces doesn't hurt..

This could be also 'Cryptosporidium'.

My vet told me, that there is no cure for it. Many dogs can get it, and the owner doesn't even know about it as grown dog's body functions will kill the parasite.
Younger pups showed symptoms as described above, plus later there was also little bit blood in their stool. This parasite can cause intestine infection in young pups and in this case they were given antibiotics for the infection.
Stool sample need to be sent to a lab to make sure if it's Cryptosporidium or not.
5/6 pups had it at the age of 4 months and symptoms were gone one day after starting antibiotic treatment.

Hope this helps someone, some day...