trial'. After the trial, if the cat's allergies have cleared up it will be placed back onto it's regular food & if after a short period of time the allergies return then it is safe to conclude that the food was the cause of the allergy. After the trial you may be asked to 'challenge' your cat by  re-introducing one ingredient back into the diet. If after 2 weeks the re-introduced food hasn't caused a flair up then add another ingredient & so on. If the allergy returns with the re-introduction of the ingredient then this is eliminated from the diet once again. Occasionally new food allergies develop over time, if this happens then it will be necessary to re-evaluate the new diet. Treatment of food allergies: Avoiding the food which caused the allergies is the best method of treatment. This may either be a home made diet or a commercial one. If you are feeding a home made diet it is important to ensure that your cat is receiving the correct nutrients in the diet.