Common Food Allergies in Pets and Why Dietary Trials Matter

When your dog or cat won't stop scratching, has recurring ear infections or suffers from ongoing digestive problems, it's natural to wonder if food could be the cause.

While food allergies do occur in pets, they're actually less common than many people think. Identifying whether food is the culprit requires a careful and systematic approach, which is where a veterinary dietary trial comes in.

What Is a Food Allergy?

A food allergy occurs when your pet's immune system reacts to a particular ingredient in their diet. This is different from a food intolerance, which doesn't involve the immune system but can still cause digestive upset.

Food allergies can develop at any age, even if your pet has been eating the same food for years.

The ingredients most commonly associated with food allergies are proteins, including:

• Beef

• Chicken

• Dairy products

• Lamb

• Eggs

• Fish

Less commonly, other ingredients may also be involved.

Signs Your Pet May Have a Food Allergy

Food allergies often affect the skin, digestive system or both.

Common signs include:

• Persistent itching

• Recurrent ear infections

• Red, inflamed skin

• Excessive licking or chewing of the paws

• Hair loss

• Vomiting

• Diarrhoea

• Frequent anal gland issues

These symptoms can also be caused by environmental allergies, parasites, skin infections or other medical conditions, so it's important not to assume food is to blame without a veterinary examination.

Why Blood Tests Can't Reliably Diagnose Food Allergies

Many pet parents are surprised to learn that there isn't a simple blood test that accurately diagnoses food allergies in dogs and cats.

At present, the most reliable way to diagnose a food allergy is through a carefully managed elimination diet, also known as a dietary trial.

What Is a Dietary Trial?

A dietary trial involves feeding your pet a specially selected diet for several weeks while completely avoiding all other foods.

During the trial, your pet must not eat:

• Treats

• Table scraps

• Dental chews

• Flavoured medications (unless approved by our veterinarians)

• Bones

• Any food other than the prescribed diet

Even a small amount of another food can interfere with the results and mean the trial has to start again.

Most dietary trials last 8 to 12 weeks, although our veterinarians will recommend the most appropriate duration for your pet.

Why Prescription Diets Are Important

Many over-the-counter "limited ingredient" or "hypoallergenic" diets may still contain trace amounts of other proteins due to manufacturing processes.

For this reason, veterinarians often recommend a therapeutic diet such as Hill's Prescription Diet during a dietary trial.

These diets are carefully formulated to minimise the risk of triggering an allergic response while still providing complete and balanced nutrition.

Depending on your pet's needs, our vets may recommend:

• A hydrolysed protein diet, where proteins are broken down into very small pieces that are less likely to be recognised by the immune system.

• A novel protein diet, containing a protein source your pet has not previously eaten.

What Happens After the Trial?

If your pet's symptoms improve during the dietary trial, our veterinarians may recommend gradually reintroducing the original food or specific ingredients to confirm whether a food allergy is present.

This step helps distinguish a true food allergy from other skin or digestive conditions that may improve for unrelated reasons.

Once the offending ingredient has been identified, many pets can enjoy excellent long-term control simply by avoiding that ingredient.

Patience Pays Off

Dietary trials require commitment and consistency, but they are one of the most valuable tools we have for diagnosing food allergies.

Although it can be tempting to offer just one small treat, every extra mouthful can affect the results. Sticking to the plan gives your pet the best chance of finding long-term relief from uncomfortable symptoms.

We're Here to Help

If your pet is constantly scratching, experiencing recurring ear infections or struggling with ongoing digestive issues, a food allergy may be worth investigating.

Our veterinary team can determine whether a dietary trial is appropriate, recommend the most suitable prescription diet, and guide you through each step of the process.

With the right diagnosis and nutrition plan, many pets with food allergies can live comfortable, happy lives with their symptoms well under control.