Prescription food goes through a process. It is hydrolyzed.
Meaning the dog won’t react to any proteins in the food despite the ingredients.
That’s why commercial food does not compare.
https://www.petmd.com/dog/what-hydrolyzed-protein-dog-food?mobi_bypass=true. excerpt below
What Is Hydrolyzed Protein Dog Food?
Protein is a vital component to any diet. Your dog’s muscles, hormones and disease-fighting antibodies are all proteins. To make what their bodies need, dogs take proteins from food, break them down into building blocks called amino acids, and combine those amino acids into new proteins.
In some animals, dietary proteins can trigger an abnormal immune response. Hydrolysis uses water to chemically break proteins into pieces that are so small that the immune system no longer reacts to them. Veterinarians typically prescribe hydrolyzed protein dog foods to treat two diseases: food allergy and inflammatory bowel disease.
