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How to Tell if Your Dog is Allergic or Food Sensitive

How to Tell if Your Dog is Allergic or Food Sensitive

By Dr. Laura Duclos, Head of the Research and Development team at Puppo.

Just like humans, dogs can experience allergic reactions signaling their immune system to release histamines. Environmental factors like pollen, grasses, mold, and fleas are all potential culprits.

But so is the food your pup eats.

Reactions to food account for about 10% of all “allergies” seen in dogs and include a wide range of symptoms. But dog food allergies aren’t the most common culprit behind your dog’s symptoms—food intolerance is more likely at the root of their discomfort.

In fact, true dog food allergies are rare, and in most cases, a diagnosed dog food allergy is actually a food sensitivity (aka intolerance).

Even though you’re feeding your pup a healthy dog food, something in their diet is causing a reaction, and it may be a reaction that has developed over time. What may have been perfectly fine to eat a year ago may now cause a problem.

Dogs can get Seasonal Allergies too

Dogs can be bothered by seasonal allergies too. If you’re noticing your four-legged friend scratching more than normal or catching them with a runny nose, it’s possible seasonal allergies are to blame.
Check out this really helpful, in-depth guide by the experts at, explaining what you need to know about identifying and treating seasonal allergies in dogs.

Let’s look at some of the dog food allergy symptoms, and how it differs from dog food sensitivity.

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How to Spot a Food Allergy

Reactions to a food allergen typically occur immediately or shortly after the ingredient/food is eaten, and the symptoms are often severe.

The primary dog food allergy symptom is itchy skin. In fact, food-related skin irritation is the cause of about 20% of the itching and scratching in dogs. Their scratching and chewing may be limited to a single hot-spot (commonly the face, feet, ears, forelegs, armpits, and anus) or a full body irritation.


You may notice your pup chewing or scratching excessively, rubbing their face with their paws or against furniture, or excessive licking and chewing their paws till they’re swollen.

However, there are a few additional signs that could point to dog food allergies.

One is that your dog has recurrent (chronic) ear problems, particularly yeast infections. Another tip-off is if their itchy skin doesn’t respond to steroid treatment, or they have skin infections that respond to antibiotics but reoccur after antibiotics are discontinued.


Other dog food allergy symptoms include:

♦ Red, itchy, inflamed ears, frequent head shaking
♦ Hair loss
♦ Hives, skin rash, or inflamed skin
♦ Open sores or hot spots
♦ Coughing, wheezing, shortness of breath
♦ Runny, red, or itchy eyes
♦ Runny or stuffy nose, sneezing
♦ Odor from feet or ears (due to secondary bacterial or yeast infections)
♦ Stomach upset, gas, vomiting, diarrhea

Some pups may have an increase in bowel movements—up to 3 or more times per day, though this is a less common symptom.

How to Spot a Food Sensitivity

Food sensitivities are chronic reactions that typically build up after repeatedly eating a specific food/ingredient. It usually takes months, or even years, before the signs appear.

Though dog food allergy and food sensitivity share many of the same symptoms, more often than not, a food sensitivity will produce a gastrointestinal reaction: diarrhea, vomiting, gas, lack of appetite, and weight loss.

One reason a food sensitivity causes gastrointestinal issues is that your dog’s system is not able to process that ingredient properly (or developed an inability to process it) for various reasons. Other times we may think our pup has a food sensitivity, but it could be a result of simply feeding them the wrong ingredients, like milk. All dogs are lactose intolerant; their body is unable to process lactose in milk products properly (they lack the proper enzymes), which leads to issues like diarrhea. This is common across all dog breeds. So skip letting your pup lick the leftover milk out of your cereal bowl.

Common Foods Causing an Allergic or Sensitive Reaction

Often, a reaction to food results from overexposure to an ingredient. If your dog is reacting to an ingredient in their food, there’s a good chance it’s the protein in their diet that’s problematic. And it’s not just meat that’s under scrutiny; some veggies contain protein, so they're not automatically safe.

The top offenders are commonly found in dog food:

Dairy Products
♦ Chicken
♦ Fish
♦ Chicken Eggs

While dogs can be allergic to plant-sourced ingredients like corn, wheat, soy, and grains, they’re actually less common allergens than many people believe. So, simply switching to a grain-free dog food won’t likley cure their symptoms.

How to Identify What Food Your Dog Is Reacting To

Luckily, diagnosing food allergies and sensitivities is a straightforward process involving feeding your pup a limited-ingredient diet—which includes no treats or table scraps. By reintroducing ingredients, one at a time, you can watch for a reaction and pinpoint the allergen. The process usually takes 6-8 weeks but could take as long as 12 weeks for the symptoms to resolve.

Two common approaches to the elimination trial:

1.  Hydrolyzed protein (prescription-only) diet provides a non-allergenic as possible nutrition

2. Novel ingredient diet uses proteins like venison, rabbit, or duck instead of beef or chicken

Before beginning an elimination trial (limited-ingredient diet), it’s important that all other potential problems have been ruled out. Atopy, flea bite allergies, intestinal parasite hypersensitivities, sarcoptic mange, and yeast or bacterial infections can all cause symptoms similar to food allergies and food sensitivity.

It’s important to note: if your dog’s reaction coincided with switching their food, they might be reacting to a sudden change as opposed to an ingredient. Whether you’re feeding puppies, adult dogs, or senior, always introduce your dog to a new diet slowly to allow their gastrointestinal system the time it needs to adjust.

How to Manage Your Sensitive Pup’s Diet

Simple. Identify the foods your dog is allergic to and eliminate them from their diet. There are a few ways to control the ingredients in their diet whether going through a dog food delivery service, running to the store, or whipping it up yourself.

1.  Make them a homemade diet.

If you decide to go the homemade route and create your own fresh dog food, it’s essential to make sure your recipe has the correct balance of protein, calories, carbohydrates, vitamins, and minerals. It’s complex and should be formulated by a pet nutritionist.

2.  Purchase food from the pet store.

This can be a little challenging, and there are a few things to watch out for when searching for the best dog food for your pup.

First, it’s important to carefully review the ingredients and look for the ‘real’ protein source. Often, the main protein is something like chicken if you see the word flavor. Chances are the main protein in “Lamb Flavor and Rice” is something other than lamb. You may inadvertently feed your pup something they react to.

Also, if the label lists natural flavoring as an ingredient, it’s usually made from pork or chicken. It’s generally just a small percentage of the recipe, and mainly included to make it taste yummy for Fido. Call the company to ask what animal the flavor was made from; some highly allergic dogs cannot even have small amounts of the protein they are allergic to, and flavor could set off a reaction.

And don’t forget, grain-free dog food is not necessarily allergen-free since grains are rarely the culprit behind your dog’s symptoms.

Lastly, there’s chicken fat. While it’s healthy compared to pork or beef fat, it isn’t a sufficient source of protein. It’s very low in actual protein structure. Though it’s safe to eat, it won't provide a balanced diet or produce a healthy dog food.

3.  Purchase food specifically formulated for your dog.

Customized dog food is definitely the simplest way to go—it takes the guesswork out. There are a handful of companies, like Puppo, that formulate dog food to support each individual pup’s sensitivities and dietary restrictions. Talk to their pet nutritionists to find out if their personalized dog food is right for your dog.

The good news is, there are plenty of healthy dog food options available for supporting sensitive pups. So, finding the right treats and the best dog food for your trusted companion isn’t as tricky as it once was.

Author Byline

Dr. Laura Duclos, PhD has a  Doctorate in Nutritional Biochemistry / Veterinary Technology and Biology, and leads the Research and Development team at Puppo. She has over 16 years of experience in developing nutritional pet food that supports animal health and wellbeing. Her clinical research has been featured in prominent publications and scientific journals. She has been an invited speaker at numerous international veterinary conferences on pet nutrition and innovation.

How to Tell if Your Dog is Allergic or Food Sensitive

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