Hi Linda-
It sounds like there is a lot of owner error at play here.
Firstly Metronidazole is an antibiotic, so you should have kept him on it for the full round. The protocols have changed and it seems 3-5 days is standard now for antibiotics. However, when you take them off an antibiotic early the body has not had a chance to completely kill off all of the bacteria that was causing the problem, so those bacteria adapt and become resistant to that antibiotic making it less effective/ineffective next time it’s needed.
Secondly, when switching to different brands of food, you need to read the recommended feeding suggestions for that particular food and not assume you can feed the exact same amount of food as your previous food. For example, Merrick Grain Free Chicken is 460 kcal/cup and 3.50% fiber, vs Science Diet Oral Care which is 275 kcal/cup and 9.5% fiber. As Cockalier Mom said, the dramatic difference in kcals and fiber accounts for his hunger and larger and more frequent bowel movements. Essentially he was being starved on accident. So no I would not say that Science Diet is the culprit here at all, nor is it a bad food.
