The most common food allergens are proteins, and feeding your dog the same food for a long time increases the potential to develop an intolerance or allergy. Though animal protein is found to be the main cause of food allergy in dogs, an allergy can potentially develop from any food. It is not easy to recognize the food allergen if your dog has had a multi-source diet. New food items keep getting added to the list of common allergens, and so it would be safer to take a preventive step by feeding your dog a diet with safe and known ingredients.

Top food allergens include the following :
According to BMC Veterinary Research, beef tops the chart of the percentage of dogs with reported reaction, followed by dairy products, chicken, wheat, soy, and others proving that the protein part is the problem and that it need not come from meat alone.

• Beef
  It is a common ingredient in pet foods, and that could be the reason that it is found to be the most common allergen. Reports show that 34% of allergy in dogs is due to beef.
• Dairy
  Some dogs cannot digest dairy well, which could be an intolerance or allergy. Lactose intolerance has symptoms of vomiting or diarrhea, which could indicate an allergy too. The distinction is that allergy has dermatological symptoms like itchiness also.
• Wheat
  Though allergic reactions are more common to meat; some dogs react to the gluten in grains like wheat. You have to check with your vet regarding the grains you feed your dog.
• Eggs
  Your dog’s immune system may react to the protein in egg yolk. Raw eggs are more likely to trigger allergy than cooked ones.
• Lamb
  Most commercial food is made of chicken or beef, so lamb is considered a good option in hypoallergenic diets. But lamb could trigger an allergy in your dog.
• Chicken
  Just as beef and lamb can cause an allergy, dogs could develop an allergy to chicken. Since it is one of the most common ingredients in dog food, your dog may have been consuming it for a long time, triggering an immune response.
• Soy
  Soy can cause allergy and other health issues in the thyroid and liver. It is better to avoid soy-based food as it does more harm than good.

Other foods include the following :

• Apart from the food you feed, your dog may eat or bite on grass, bark, dirt, wild berries, dung, or harmful things from the garbage like rotten food or dead animals, and any of it could be cause for allergy.
• If you are not sure of the treats and the supplements’ contents, avoid them, especially if your dog is on a hypoallergenic diet. Gelatin coated capsules have been found to cause allergy in some dogs.
• Additives such as flavors, colorants, and preservatives are other food substances that could trigger allergies.
• If your dog has an allergy for one particular type of food, they may develop an allergy to other food in the same category; for example, if they have an allergy to chicken, they may have it to duck too.