Food vs Environmental Allergies in Pets: How to Tell the Difference

Is your dog constantly scratching, licking their paws or suffering from recurring ear infections? Or perhaps your cat has developed itchy skin or is grooming themselves more than usual?

Allergies are a common cause of skin problems in pets, but did you know that not all allergies are the same?

Two of the most common types are food allergies and environmental allergies. While they can cause very similar symptoms, the triggers and approaches to diagnosis and treatment are quite different.

Understanding the difference is an important first step towards getting your pet some relief.

What Are Food Allergies?

Food allergies occur when a pet's immune system reacts to a particular ingredient in their diet. The reaction is usually triggered by a protein source, although other food ingredients can occasionally be responsible.

Common food allergens in dogs and cats include proteins such as:

• Beef

• Chicken

• Dairy products

• Fish

• Eggs

Contrary to popular belief, food allergies aren't necessarily caused by feeding a particular food for too long. A pet can develop an allergy to an ingredient they have eaten for years without any previous problems.

Food allergies can develop at any age and may cause skin problems, digestive symptoms or both.

What Are Environmental Allergies?

Environmental allergies occur when a pet's immune system overreacts to substances in their surroundings.

These substances, known as allergens, can include:

• Grass and tree pollens

• Flowering plants and weeds

• Dust mites

• Mould spores

• Other airborne environmental allergens

Environmental allergies are commonly associated with a condition called atopic dermatitis.

Some pets experience seasonal flare-ups, while others have symptoms throughout the year, depending on the allergens involved.

Food vs Environmental Allergies: What's the Difference?

One of the challenges with diagnosing allergies is that food and environmental allergies can look remarkably similar.

Both can cause itching, skin inflammation and recurring ear infections. However, there are some patterns that may help our vets distinguish between them.

1. When Do Symptoms Occur?

Food allergies: Symptoms can occur at any time of the year because the pet is regularly exposed to the ingredient in their food. They generally don't follow a seasonal pattern.

Environmental allergies: Symptoms may become worse at particular times of the year, particularly when pollen levels increase. However, allergies to dust mites and mould can cause year-round symptoms.

2. Which Areas of the Body Are Affected?

Food allergies: Dogs may experience itching around their ears, paws, face, belly and rear end. Recurring ear infections are also common. Some pets experience digestive symptoms such as vomiting, diarrhoea or frequent bowel movements.

Environmental allergies: Commonly affected areas include the paws, face, ears, armpits and belly. Cats may develop scabs, hair loss or excessive grooming, particularly around their head and neck.

There is considerable overlap between the two, so the location of the itching alone cannot confirm the cause.

3. Are There Digestive Symptoms?

Food allergies: Some pets with food allergies experience gastrointestinal problems alongside skin irritation. These may include vomiting, diarrhoea, soft stools or increased bowel movements. However, many food-allergic pets have skin symptoms without any digestive problems.

Environmental allergies: These generally cause skin and ear problems rather than digestive symptoms.

If your pet has recurring digestive issues as well as itchy skin, a food allergy may be worth investigating.

4. Does Your Pet Respond to Dietary Changes?

Food allergies: Symptoms may improve when the offending ingredient is removed from the diet. However, this needs to be established through a properly managed dietary trial rather than simply switching between different commercial foods.

Environmental allergies: Changing your pet's food generally won't resolve environmental allergies, although some pets can have both conditions at the same time.

How Are Food Allergies Diagnosed?

The most reliable way to diagnose a food allergy is through an elimination diet trial.

This involves feeding your pet a specially selected diet for a set period, usually around eight weeks or sometimes longer, depending on their symptoms and response.

Our vets may recommend either:

• A hydrolysed protein diet: The proteins are broken down into smaller components, making them less likely to trigger an immune response.

• A novel protein diet: This contains a protein source your pet has not previously eaten.

During the trial, your pet must eat only the prescribed diet. This means avoiding treats, table scraps, flavoured medications, chews and other foods that could interfere with the results.

If symptoms improve, our vets may recommend a controlled food challenge by reintroducing the previous diet to see whether the symptoms return. This helps confirm whether a food allergy is responsible.

Simply changing your pet's food and noticing an improvement isn't enough to establish a diagnosis.

How Are Environmental Allergies Diagnosed?

Diagnosing environmental allergies involves a process of elimination.

Our vets will examine your pet, discuss their medical history and look at the pattern of their symptoms.

Other potential causes of itching must first be ruled out, including fleas, mites, skin infections and food allergies.

In some cases, allergy testing may be recommended to identify specific environmental allergens. This is particularly useful when considering allergen-specific immunotherapy, a treatment designed to gradually reduce the immune system's reaction to particular allergens.

It's important to understand that allergy testing alone cannot diagnose environmental allergies. The results need to be interpreted alongside your pet's clinical signs and history.

Can Pets Have Both Food and Environmental Allergies?

Yes! Some pets can have both food and environmental allergies.

This can make diagnosis and management more complicated, particularly when symptoms overlap.

For example, a dog may have an environmental allergy that causes seasonal itching but also have a food allergy contributing to ongoing skin irritation.

In these cases, our vets may recommend investigating and managing both conditions.

What Can You Do to Help Your Itchy Pet?

If your pet is scratching more than usual, licking their paws, experiencing recurring ear infections or developing irritated skin, it's worth arranging a veterinary examination.

In the meantime:

• Keep up with regular flea and parasite prevention.

• Wash your pet's bedding regularly.

• Wipe paws after outdoor activities to remove pollen and other irritants.

• Avoid introducing multiple new foods or treats while investigating a possible food allergy.

• Keep a record of your pet's symptoms, including when they occur and whether they appear to get worse at certain times of the year.

Avoid making major dietary changes or starting treatments without discussing them with our vets first.

Helping Your Pet Find Relief

Whether the cause is something in their food bowl or something in the environment, persistent itching is uncomfortable and can significantly affect your pet's quality of life.

The good news is that both food and environmental allergies can often be managed successfully with the right diagnosis and an appropriate treatment plan.

If your pet is constantly scratching, licking or chewing their skin, don't assume it's just a passing irritation.

Book an appointment with our clinic. Our vets can help investigate the cause of your pet's symptoms and find the best way to get them feeling comfortable again.