Your dog scratches frequently, even with no fleas in sight. Their ear is constantly inflamed. Their coat is dull, and their skin is reddened. Or perhaps their stomach has been rumbling and their stools irregular for weeks.

You've tried everything — different shampoos, supplements, antiparasitic treatments. But the problem keeps coming back.

One of the most underestimated causes in these cases is what you see every day: the food bowl.

Food allergy or intolerance? The difference matters

First, an important clarification that often causes confusion.

Food allergy — is an immune system response. The dog's body mistakenly identifies a food protein as a threat and reacts by producing antibodies. Symptoms can appear even with minimal amounts of the offending food and tend to be constant over time.

Food intolerance — is a digestive, not immune, response. The body struggles to process a specific ingredient. Symptoms are primarily gastrointestinal and tend to be proportional to the amount ingested.

In both cases, the solution is similar — identify the offending food and eliminate it from the diet — but allergies tend to have broader and more persistent symptoms.

Symptoms: how to tell if the problem comes from food

The most challenging aspect of food allergies in dogs is that the symptoms overlap with those of many other conditions — from atopic dermatitis to environmental allergies, from parasites to skin infections. No single symptom alone can "diagnose" a food allergy.

What matters is the combination and persistence over time.

Skin symptoms

• Intense and constant itching — 
  paws, ears, groin, armpits, muzzle
  
• Redness and inflammation of the skin, especially in the folds
• Dull, brittle, or excessive shedding coat
• Lesions from scratching — the dog scratches until wounds appear
• Recurrent ear infections — ear infections that reappear after each treatment

Gastrointestinal symptoms

• Frequent vomiting — not occasional, but recurrent
• Chronic diarrhea or continuously soft stools
• Abdominal bloating after meals
• Excessive flatulence
• Weight loss despite apparently normal feeding

Behavioral symptoms

• Restlessness, especially at night when itching is most intense
• Irritability related to constant physical discomfort
• Decreased appetite in severe cases

💡 Important sign: if skin symptoms are present all year round without seasonality, and do not improve with antiparasitic treatments, food allergy is one of the first things to rule out.

The most common foods responsible for allergies in dogs

Contrary to what many people think, dogs don't develop allergies to new foods — they develop them to foods they have eaten for a long time. The immune system needs repeated exposure before developing an allergic response.

The most frequent allergens in dogs are:

🥩 Beef — the most common, present in many commercial foods 🍗 Chicken — second most frequent allergen, often hidden as "poultry meal" 🐄 Dairy — milk, cheese, yogurt 🌾 Wheat and gluten — common in economic dry food 🥚 Eggs 🐷 Pork 🐟 Fish — less common, but present

⚠️ Pay attention to labels: many commercial foods contain "hidden" proteins — chicken can appear as "poultry extract," beef as "beef meal." Always read the full ingredient list.

How it's diagnosed: the elimination diet

There is no 100% reliable blood test for food allergies in dogs. Serological tests available on the market have limited reliability and are often a source of false positives.

The gold standard diagnostic method is the elimination diet — the only truly reliable tool.

How it works

The dog is fed a diet with proteins and carbohydrates they have never eaten before — called "novel proteins" or "hydrolyzed proteins." The most common novel proteins are:

• Horse
• Kangaroo
• Ostrich
• Deer
• Insects (increasingly used)

Alternatively, diets with hydrolyzed proteins are used — proteins broken down into fragments so small that the immune system no longer recognizes them as a threat.

Duration

The elimination diet must last at least 8-12 weeks strictly. No other food, no treats, no table scraps. Even a single bite of the suspected food can invalidate weeks of testing.

How it's interpreted

If symptoms improve significantly during the elimination diet, it is likely that the cause is dietary. At that point, foods are reintroduced one at a time — if symptoms return with a specific ingredient, that is the culprit.

What to do while waiting for diagnosis: skin care

While you await the results of the elimination diet — long and often frustrating weeks — your dog continues to have irritated skin and a compromised coat. There are things you can do to alleviate discomfort without interfering with the diagnostic process.

Hair and skin care

The skin of a dog with food allergies is already inflamed and reactive. Any aggressive product — shampoo with synthetic perfumes, strong surfactants, dyes — can worsen the situation.

During this period, it is essential to use products with the fewest possible ingredients, all natural and delicate.

The Fragrance Free ShizenPet line is formulated precisely for this: no essential oils, no fragrance, only functional ingredients — ionized bicarbonate, 0.9% vegetable surfactants, pomegranate seed oil, and grape seed oil. The bare minimum

to clean and hydrate without adding potential irritants to already compromised skin.

Paws — the most exposed area

The paws of dogs with food allergies are often among the areas most affected by itching. The dog licks continuously, creating that characteristic reddish fur between the toes (oxidation from saliva).

Regular paw cleaning with Dry Shampoo ShizenPet Fragrance Free reduces the accumulation of environmental allergens that add to food allergens, alleviating the total load on the immune system.

Prevention: what we can do before an allergy appears

There is no way to prevent food allergies with certainty. But there are practices that can reduce the risk or slow down development:

Dietary variety from puppyhood — exposing the dog to multiple protein sources from a young age seems to reduce the risk of developing allergies to specific proteins in adulthood.

Read labels — choose foods with a short, transparent ingredient list, avoiding generic "meat meals" that hide undeclared allergens.

Do not change food frequently without reason — frequent and sudden diet changes stress the digestive system. If you want to change, do it gradually over 7-10 days.

Beware of treats — many commercial treats contain beef or chicken. If the dog shows sensitivity, even one treat a day can be enough to keep the allergic response active.

When to go to the vet

Food allergies cannot be managed alone. The vet is essential for:

• Excluding other causes (parasites, atopic dermatitis, fungal infections)
• Properly setting up the elimination diet
• Managing acute symptoms with specific therapies (antihistamines, corticosteroids if necessary)
• Interpreting diet results and planning food reintroduction

If symptoms are intense — open skin lesions, significant weight loss, severe ear infections — don't wait: early intervention prevents the situation from becoming complicated.

Conclusion: the food bowl can make a difference

Food allergies in dogs are more common than often thought — and it often takes months or years to diagnose them because symptoms are attributed to other causes.

Observing your dog, keeping a symptom diary, and consulting your vet with precise information are the first steps to finding the right answer.

Food is the foundation of health. It's worth choosing carefully. 🌿

Read also: Why does your dog lick their paws? | Does your dog eat grass? Here's what they're trying to tell you | Is baking soda bad for dogs and cats?