Duck liver is an excellent option for dogs who have allergies to chicken or sensitive stomachs. It is a good source of protein, Vitamin A, iron and selenium. It is also twice as rich as Vitamin B12 as chicken liver and has up to ten times as much vitamin D. Duck is also a great option for pets with allergies to chicken or sensitive stomachs. Novel proteins like duck may help alleviate gastrointestinal upsets or skin irritation. It should be given in moderation as a part of a balanced diet.