Anyone whose dog has had allergies or other ongoing skin or digestive issues knows the pain of seeing your pup in discomfort. And it’s all the worse when you can’t immediately put your finger on what’s causing the problems and how to bring relief. In these cases, a step-by-step test known as an elimination diet may be called for.
When your vet suspects your dog has a food allergy or intolerance, they may suggest that you conduct what’s known as a dietary elimination trial, aka an elimination diet.
To give you a sense of what’s involved and if you may want to consider this option, here’s more information on what an elimination diet is, what it’s used for, and how to conduct the trial at home (under the supervision of your veterinarian, of course).
What Is an elimination diet for dogs?
An elimination diet is a diagnostic tool to help identify a specific food that is causing a reaction and/or health problem for a dog.
An elimination diet is what it sounds like: a process whereby you eliminate the foods your dog typically eats. As part of the protocol, you feed a restricted, “bland” diet for a period of time (usually several weeks) and then slowly reintroduce foods until the offending ingredient is found. This ingredient can then be avoided in the future to avoid its ill effects.
An elimination diet is primarily done for the diagnosis of a food intolerance or allergy, and, if a dietary troublemaker is identified, it can lead to a new diet as a treatment. It should only be done under the guidance of your vet, and shouldn’t be continued long-term, as it could lead to harmful nutritional deficiencies and imbalances.
When to use an elimination diet
Under vet guidance
An elimination diet should only ever be administered on the advice and under the guidance of a veterinarian. First, a vet can determine if your dog has a condition—most commonly an allergy—for which an elimination diet is an appropriate diagnostic step.
A vet can also ensure you’re following the right steps to make sure the trial is effective, and they can help ensure your pup is still getting sufficient nutrition to sustain their bodily functions while on the diet.
Vets can also clue you in to where hidden ingredients may be lurking in pet foods. Labels on traditional pet food bags often aren’t as accurate as they should be–there are common allergens that may be included in the foods but not listed. For example, some pet foods may list “natural flavor” as an ingredient without further stipulating what protein source or ingredients are contained in that flavor. So, people may believe they are buying a food free of a certain type of protein, like chicken, when there is actually chicken contained in the product via “natural flavor.” This is why many people whose dogs have allergies find that those allergies subside when they switch from heavily processed food to fresh food.
One recent study cited “concerns that commercial pet foods might contain unlisted food sources that could negate the usefulness of performing food trials,” and concluded that “the mislabeling of pet foods appears rather common.”
The vet will also be able to help manage the process of eliminating foods, as your dog may initially not be a fan of their bland diet. This can cause issues with your pup sticking to their new diet, and the vet should be able to suggest the best way to get through the first tough spots.
And, your vet can determine if an elimination diet isn’t appropriate for your pet because of a condition like diabetes.
To identify allergies
Like humans, dogs can have food allergies and food intolerances. A food allergy, also called a food hypersensitivity, occurs when the dog’s immune system sees a food protein as a foreign invader and overreacts.
Dogs can be allergic to the proteins or glycoproteins of one or more food ingredients, commonly meat or carbohydrate sources. While any individual dog can be allergic to almost any food ingredient or ingredients, many vets point to animal proteins as the most common culprits. A study published in 2016 that showed the most common triggers for food allergies in dogs are beef, dairy products, chicken, and wheat.
The most common signs of food allergy can be similar to the signs of environmental allergies and include:
- Itchy skin
- Hair loss
- Hot spots (skin infections)
- Paw infections
- Ear infections
- Vomiting and diarrhea (more often associated with food intolerances)
For dogs diagnosed with food allergies, finding a diet free from allergic ingredients is life-changing.
That’s where the elimination diet comes in. By having your pup follow this diet, you can isolate and remove the trigger, and allow their immune system to settle again, soothing their symptoms. Continued exposure to an allergen can also lead to the condition worsening, so it’s important to visit a vet as soon as you notice any signs of allergy or food intolerances in your pet.
How to do an elimination diet
An elimination diet is simple in theory, but not always easy in practice. It takes some time, patience, and willpower to ensure you’re truly ruling out potentially offending foods. Your vet can recommend a bland diet to feed during the trial, and provide tips and tricks for getting through all the phases.
While your vet may have specific instructions and variations, here are the steps you can expect to follow to conduct a dietary elimination trial.
Step 1: Create a list or spreadsheet to capture a thorough history of all the foods your dog regularly consumes, including treats, supplements, and medicines.
Step 2: Work with your vet to arrive at a nutritious but bland diet for your pet. This will usually include one protein and one carbohydrate to give your dog a good amount of energy, while still being less aggravating for their immune system. Ideally, you’ll feed a home-cooked diet, so you can be doubly sure of everything that’s going into the bowl during this time.
The protein will likely be from an unusual source, because everyday proteins are commonly the source of the allergy. The more uncommon the protein, the less likely it is a part of your dog’s normal diet, and the less likely that they are already sensitive to it.
Step 3: Follow the elimination diet as directed by your vet—usually for anywhere between 6 and 16 weeks. This helps to completely eliminate the ingredients that could be causing the allergy, and allows the symptoms to calm down. Your vet may also recommend that you shift to and from this diet gradually to reduce digestive upset caused by changing diet.
Remember to refrain from giving your dog any treats or extras, and speak to your vet about any medications or supplements that your dog takes. Things like flavored supplements and toothpaste may interfere with the trial. It may help to take notes during this period to track how your dog is feeling as the diet progresses. Make sure everyone in your household is on board with the plan.
An analysis of multiple studies found that by 5 weeks into an elimination diet, 80% of participating animals showed remission of cutaneous signs.
Step 4: As directed by your vet, reintroduce a suspected allergen. Most of the time the vet will have a suspicion as to what the allergen is. Typically, you’ll reintroduce one ingredient at a time in small amounts while you monitor for any signs of a reaction. The reintroduction of the allergen will confirm whether it is or isn’t the issue. If your dog has a flare-up, then the reintroduced food is the cause of their symptoms and can be avoided in the future. If they don’t have a reaction, move onto step five.
Your vet may recommend you do “provocative testing” or a challenge step, which means feeding the original diet to see if they show signs.
Step 5: Keep feeding the bland diet and reintroduce another suspected allergen. This allows you to eventually narrow down the most likely problem food, which can then be avoided in the future.
With patience, and communication with your vet, an elimination diet can be a powerful tool in diagnosing allergies.
If your dog is suffering from itching, digestive issues and other signs of allergies, be mindful of their daily diet, and be careful not to rely too heavily on “limited ingredient” pet foods. The term “limited ingredients” is not regulated, and there’s ample evidence that limited-ingredient products may not be very limited. A 2018 review of research found that 33-83% of non-prescription “limited ingredient” pet food products contained ingredients not listed on the label.
Again, while many dog owners find their dog’s allergies resolve when they eliminate a certain food or ingredient, for others, avoiding heavily processed, extruded foods and feeding a diet of fresh, whole food can make all the difference.