The fiber can be added with each meal daily. You just need to find out which dose of that particular fiber works best and start with a smaller amount. Some dogs need more fiber and some dogs do better with less fiber. That’s something you’ll need to figure out though. For a 25 lb dog: 1/2 teaspoon of psyllium or coconut fiber or chia or a tablespoon of pumpkin puree. These numbers aren’t written in stone. My 20 lb dogs either get 1/4 tsp of psyllium or a whole teaspoon of chia.
You might also try a limited ingredient diet if there are any out there that are appropriate for large breed puppies until he gets better.
He was a little too young to leave his mother (IMO). Younger pups might not have a strong enough immune system (since he’s meds for mites) and not a strong enough gut (a healthy amount of good bacteria in his intestines) to be eating processed hard kibble. And receiving vaccinations and being on a prescription are both stressors. I’d give him probiotics to strengthen his gut.
At the end of the day, we just want are pups to be better. Even if that means Science Diet for a couple of weeks or months until he is stronger.
