Food allergies are relatively rare in dogs and cats. For every 5 dogs with atopic allergies, there is one with food allergies. Food allergies are also rarely only food allergies. Most pets with food allergies also have some atopic allergies.
Food allergy symptoms include year-round itching, recurrent skin and ear infections, intermittent loose stool, and licking around the anus. Dogs are unique in that they often develop an allergy or intolerance to the protein in their food. They typically develop issues when they are young, between 1 and 4 years of age. This allergy develops over time; it doesn’t typically appear soon after switching foods.
The only way to determine if your pet has a food allergy is to perform a diet trial. There are food allergy blood tests available, but they are not accurate, so unfortunately a diet trial is the only way to know for sure if your pet has food allergies. This trial consists of transitioning to a veterinary prescription dog food. There are two categories of prescription dog foods: “novel protein diets” and “hydrolyzed protein diets.” Novel protein diets are made from a protein source that your pet has not eaten before, such as kangaroo or venison. It is increasingly hard to find true novel proteins for many pets because many foods contain multiple proteins, and more “exotic” meats are frequently used in treats now. The other concern with novel protein diets are cross-reaction allergies. This is where a dog may be allergic to chicken but is also allergic to duck, even if they had never had duck before. In general, novel protein diets are only 75% effective for animals with food allergies. The second and better option is hydrolyzed protein diets. These are foods in which the protein is broken down to a molecule too small for the body to recognize as an allergen.
During this food trial, it is very important that your pet to eat nothing other than this diet. This includes dog treats, human table food, pill wrap, or flavored medications; if they do get these treats then we need to start the trial over.
Food trials last 8–12 weeks, as it frequently takes this long to see improvement in itching and infections. During this trial, you should keep track of your pet’s daily itch level to monitor for trends. We recommend an itch level in which itch level 1 is normal and itch level 10 is non-stop itching to the point of bleeding.
If your pet responds well to the diet (25 to 100% decrease in itch levels) the next step is feeding their old diet again to see if the itching and infections return. This step allows us to differentiate food allergies from seasonal allergies that may no longer be present in the environment. If the itching and ear/skin infections return upon re-feeding their old diet, then we will want your pet to stay on the prescription allergy diet lifelong.
We recommend Hill’s Derm Complete, Royal Canin Ultamino, or Purina Elemental diet for your pet. Please transition to this new food over 4 days:
- Day 1: 25% new food/75% old food
- Day 2: 50/50
- Day 3: 75% new food/25% old food
- Day 4: 100% new food
This will help decrease upset stomach issues.