@OP, I hope your veterinarian continues to be helpful and answers your questions.
(excerpt below from http://www.petmd.com/dog/conditions/infectious-parasitic/c_multi_giardiasis?page=2) Parasitic Diarrhea (Giardiasis) in Dogs
Treatment
Treatment is typically done on an outpatient basis unless the dog has become sick and weak. Prescription drugs along with bathing are combined to reduce the likelihood of repeat infection and to remove the parasite from the dog’s body. Repeat fecal exams are often required to confirm that the infection has been removed, as an ongoing (chronic) infection can be debilitating for the animal.
Living and Management
It is important to observe for signs of dehydration, especially in younger animals. Administering the prescribed medication and taking the animal back in for examination are also important in a successful recovery.
Prevention
Since one of the highest incidences of the infection spreading is in a kennel, seek places that offer private spaces for pets in order to avoid contamination from the other animals.
