Chicken fat is an excellent source of essential fatty acids and an excellent source of energy.  When fed appropriately for the metabolic needs of the individual, and in moderation, fats are essential to good health and survival. Without fat in your pet’s diet, their fur, skin, eyes, immune system, brain, and blood cells would suffer. Dogs need good-quality fat especially if they reside in cold climates, or exert lots of energy running or hiking, racing long distances, or herding cows and sheep. Higher fat diets in the winter time will keep your pets warmer and will provide them with better stamina to adapt to the cold and wind.

Typically irritants are animal or plant proteins, not fat.  What some people or some animals, for that matter, are really allergic to are the proteins - proteins called antigens. Oils do not contain antigens or proteins. So if someone is allergic to chicken or corn, for example, this is not a concern. They will not be allergic to the chicken fat in any of the Timberwolf diets.