Thanks for the additional information.
Diarrhea in puppies is most often due to one of three problems:
- Intestinal parasites
- Dietary indiscretion or eating something from the house or yard that does not sit well in their stomach
or intestines or something that is stuck inside of the intestines
- Intolerance to the ingredients in the food
There are other more rare conditions such as Addison's disease, which is a low cortisone level in the body or pancreatic enzyme deficiencies though these are usually only suspected if the above three are completely ruled out.
I am glad that you are taking him to the vet. I would definitely have them check a fecal sample to rule out parasites as the cause. If the vet does not see any parasites I would still recommend treating him with a dewormer just in case one of the parasites was missed on the fecal test which can happen very easily.
If the deworming and the fecal test do not give any answers, then I would consider a different diet for him. Blue Buffalo is not a bad food at all, but I have seen many young puppies that do not digest the ingredients very well and simply by switching to a different food you may see all of his problems resolves.
I had one of my patients that was a doberman puppy on the Blue Buffalo and we decided to switch him over to Royal Canin puppy and within a few days he was normal therefore I would recommend using one of the core food companies like Royal Canin, Science Diet, Nutro Max, or Eukanuba. These diets are all well researched and are very healthy for your puppy.
The drinking excessively may be because he is losing extra fluids from having softer stool therefore should resolve once his stools are better.
Hope this helps -please reply if you have any other questions.