That is a shame the meds did not clear him up and he still has loose stool.

Can you give a bit more background on him? How old is he? What has he been fed in the past and did he have firm stool on that food? Has he been healthy up until recently?

It could be a food intolerance. I have a 12 plus yr old dog that developed a food intolerance about a yr ago and it is tough to find what she can eat and digest. She does great on cooked sweet potato (about 5 ounces) and cooked fish (about 4-5 ounces) twice a day but I am trying other meats now.

If it is not caused by a parasite, what else could it be? Did the vet have any ideas?