It's easy to fall into the trap of thinking the hypoallergenic dog food you're buying for Duke will take care of what ails him. After all, the label implies the food has a low chance of causing an allergic reaction. The right protein and carbohydrate sources are the ones that don't trigger a reaction.
Anatomy of an Allergy
When all's well with Duke's health, the food he eats breaks down into nutrients and amino acids, passing through his gastrointestinal -- or GI -- tract and into his bloodstream. If any partially digested foods make it into his bloodstream, his immune system kicks in, triggering an allergic reaction. Whenever Duke eats food he's sensitive to, his body mounts the same response, resulting in the symptoms you're seeing, such as a skin rash or hives, obsessive licking, paw biting and scratching. Occasionally you'll see some nausea or vomiting, but those are more common to food intolerance, which is a digestive problem. Other signs of food intolerance include gas, diarrhea, bloating and digestive distress.
Provoking a Reaction
There's no one-size-fits-all approach when it comes to hypoallergenic dog food. DogFoodAdvisor.com notes the carbohydrates most likely to trigger an allergic reaction are corn and wheat. Other potentially troublesome dog food ingredients include beef, chicken, lamb, dairy, soy and yeast. However, just because those are common causes of an allergic reaction doesn't mean one of them is responsible for Duke's skin rash or excessive scratching. The key to finding an acceptable hypoallergenic dog food is to learn what ingredient is causing your pup's allergic reaction. Your vet will work with you to develop a food trial, or elimination diet, to give Duke's immune system a rest and determine what's causing the problems.
A Novel Approach
Since something in Duke's food is causing his reaction, the first step is to look at what he's eating and steer clear of it. If he's eating lamb and rice, a hypoallergenic choice for him would be a diet that doesn't contain either ingredient. A diet using different ingredients for your dog is considered a novel diet. Carbohydrate sources in hypoallergenic dog foods include rice, sweet potatoes, white potatoes, green peas, oats, barley, pumpkin, yams and quinoa. Alternative protein sources include rabbit, tuna, salmon, duck and other game meat.
The Hydrolyzed Approach
An alternative to switching ingredients is to use a single source for protein and a single carbohydrate, while changing the protein's form. A hydrolyzed chicken diet would break the chicken into particles so small that Duke's immune system doesn't recognize the protein as a potential problem, essentially tricking his immune system. These diets tend to use corn starch and cellulose as carbohydrate sources.