My dog has had IBD for several years...he was diagnosed right around 3 years ago. We have been on the Royal Canin hydrolyzed food for all of that time and it's been great for him. His signs (chronic vomiting) have completely gone away unless he gets into people food somehow. While reading the list of ingredients it may seem 'unhealthy' but the prescription diets have real scientific studies behind them showing they work and dogs do well on them. A dog with IBD basically has an allergic reaction to the food, and usually its the proteins. The hydrolyzed diets are specially processed to make the protein too small for the dog's immune system to recognize (they still digest them normally though) which prevents the inflammation. I was told that Royal Canin deep cleans the entire plant before they make any hydrolyzed food to avoid contaminating it with any other proteins. My internal medicine specialist said the over the counter 'limited ingredient' foods are not processed that carefully and may be contaminated and cause the inflammation. I've never heard of the Petco brand and would need to read more but I am skeptical that it's truly hydrolyzed at the price I see advertised online...that special hydrolyzed processing makes the food very expensive! A similar sized Royal Canin bag costs over $70, and the Hill's is closer to $90. Purina makes a hydrolyzed diet called HA you could look into as well. Luckily my dog is smaller and only eats about 7 lbs a month.