Hi Sir. If your pet has acute gastritis, fast your pet for 12 -24 hours.. After 24 hours without vomiting you can feed a small amount of highly digestible bland foods such as plain cooked chicken, Bone broth, Rice, Boiled sweet potatoes, pureed pumpkin, Plain yoghurt, Boiled eggs (u could remove yolk during gastritis)..A cooked egg could be good for your pet unless your pet has pre existing health condition such as Acute pancreatitis or Food allergy to eggs.