When itching isn’t normal: How food allergies affect pets

As a chocolate Labrador retriever, Cookie has always been energetic and playful, often engaging in agility training to stay active. When her owner first noticed head shaking and increased stool, he assumed it was common for her breed and activity level. It wasn’t until frequent ear infections set in — leading to a frustrating cycle of veterinary visits — that he became concerned about an underlying issue.  

Pet owners often watch their dogs and cats scratch, shake their heads and seem uncomfortable, without knowing how to help. Some pets experience occasional itching, while others struggle with constant scratching, ear infections, digestive issues and ongoing discomfort.

What many pet owners don’t realize is that precise nutrition may be part of the solution, helping ease these signs and support long-term health. When Cookie’s owner eventually consulted a veterinary dermatologist, he began to learn that firsthand.  

Itching and skin issues are more common in pets than many people realize. Skin allergies are the most common health issue for dogs. In 2023, over 410,500 cases were reported representing 20% of unique claims for dogs.¹

Despite how often these issues occur, food allergies are frequently overlooked as a possible cause. Food allergies account for just 1-2%² of veterinary visits but can be higher in itchy dogs seen for allergies, with reports of 18-29%. In many cases, food allergies go undiagnosed or are misattributed to other causes.

What it looks like and why it’s easy to miss

Food allergies occur when a dog or cat develops a sensitivity to a protein source in food. The most common proteins dogs are allergic to include beef, dairy, wheat, egg and chicken.³ Food allergies in pets can show up in many ways. According to Dr. Brittany Lancellotti, a veterinary dermatologist, recognizing these signs is the first step toward helping a pet feel better.

Beyond obvious scratching and itching, food allergies may appear as licking, chewing or biting at the skin, including a behavior known as “corn cobbing,” when pets chew on their own limbs and paws.

Recurring ear infections are another red flag.

Digestive issues, such as changes in stool frequency or ongoing digestive upset, may also signal a problem. These gastrointestinal signs can seem unrelated to skin and ear issues, even though they are often part of the same underlying cause. Together, these signs can escalate, leading to poor sleep and persistent discomfort that affects both pets and their owners.

Many of these signs may seem “normal.” All dogs scratch from time to time. Pet owners often blame itching on seasonal allergies, dry weather or breed tendencies. They may not realize that the frequency, intensity or combination of signs points to something more serious — and that nutrition can play a crucial role in the management plan of the pet.

Diagnosing food allergies can be challenging, which makes early consultation with a veterinarian critical.

“We do not have a reliable blood test, hair test, saliva test or skin test for food allergies in pets,”⁴ explained Dr. Lancellotti. “Food allergies are a very complicated disease process, and the only reliable test we have at this time is to feed a diet that is designed to not trigger the animal’s immune system, and nothing else, over the course of 8 to 12 weeks.”

This is where an elimination diet trial may come in, and why working with a veterinary specialist to use specifically formulated therapeutic diets can make a meaningful difference.

Cookie’s journey: From frustration to relief

Cookie’s story began like many others. Her owner noticed she was shaking her head and scratching her ears during agility training, an activity she normally loved. Over time, the scratching, head shaking and ear infections became more frequent, and digestive issues developed.

It was clear something wasn’t right.

After multiple veterinary visits without lasting relief, Cookie’s owner decided to consult with Dr. Lancellotti, who specializes in identifying and treating food allergies.

Dr. Lancellotti recommended starting an elimination diet trial, a structured and supervised feeding routine performed at home that requires commitment and patience. This approach can also help the veterinary team reach a diagnosis by narrowing in on a potential cause of the allergy. The trial must use a diet that contains either a protein the pet has never eaten before or a hydrolyzed diet, in which the protein is broken down so small that the immune system does not react.

For eight to 12 weeks, Cookie ate only a specially formulated therapeutic diet — no other foods, treats or table scraps. Regular veterinary check-ins monitored her progress.

Dr. Lancellotti recommended Royal Canin’s Ultamino diet, a veterinary-exclusive formula designed to support both the diagnosis and dietary management of food allergies in cats and dogs. According to Dr. Todd East, director of veterinary affairs at Royal Canin North America, this type of extensively hydrolyzed protein diet is essential for accurate diagnosis. This is especially important because research has found that up to 83%of over-the-counter diets labeled as limited ingredient tested positive for ingredients not listed on the label.⁵

By breaking protein down to the amino acid level, Ultamino helps reduce the risk of a pet showing signs of food sensitivities. This precision allows veterinarians to safely introduce different proteins later to identify the source of the reaction. The process, known as challenge feeding, involves carefully reintroducing specific ingredients to pinpoint which foods cause signs.

In Cookie’s case, the results were clear. At the start of the diet trial, she underwent extensive ear treatment to address damage caused by food allergies. This established an important baseline: If food allergies were the root cause, having the diet in her management plan should help her ears remain healthy.

Within weeks on the elimination diet, her stool improved and her skin was less red and irritated. Most notably, the ear infections stopped*. Once the offending protein was identified, Cookie maintained on a balanced diet and the owner knew which high value foods he could safely use as treats during agility training.

While results vary from pet to pet, Cookie’s quality of life changed dramatically. She became more energetic and focused, slept better and returned to being the active, happy dog she had been before.

The change wasn’t limited to Cookie. Her owner felt relief, too. The frequent veterinary visits stopped, and the worry over recurring ear infections faded.  He could finally relax, knowing Cookie was comfortable again.

Taking the next step

If a pet shows signs of food allergies, an elimination diet may be worth discussing with a veterinarian. Success requires patience, strict adherence to the recommended diet protocol — including no treats or table scraps — regular monitoring and the use of high-quality therapeutic diets.

Ongoing scratching, ear infections or digestive issues are not problems pets should simply live with. Pet owners who notice these signs should schedule a veterinary appointment and share their observations. A veterinarian can help determine whether food allergies may be involved and whether an elimination diet trial is the right next step.

As Cookie’s owner discovered, the source of a pet’s discomfort may be in the food bowl — and the relief can be truly life-changing.

If your pet shows ongoing signs of itching, ear infections or digestive issues, talk with your veterinarian about whether a food allergy could be involved. Visit royalcanin.com for more information.

*While these results were observed in this specific case, each pet may respond differently and pet owners are encouraged to speak to their veterinarian if they have any questions or concerns about their pet’s health.

Footnotes

(1) Nationwide, “Skin allergies, gastrointestinal disease among most common conditions that prompt veterinary visits,” accessed February 2026, https://news.nationwide.com/most-common-conditions-that-prompt-veterinary-visits-2024/

(2) Olivry and Mueller, BMC Veterinary Research, “Prevalence of Cutaneous Adverse Food Reactions in Dogs and Cats,” accessed February 2026, https://link.springer.com/article/10.1186/s12917-017-0973-z

(3) Mueller, Olivry and Prelaud, BMC Veterinary Research, “Common Food Allergen Sources in Dogs and Cats,” accessed February 2026, https://link.springer.com/article/10.1186/s12917-016-0633-8

(4) Olivry and Mueller, BMC Veterinary Research, “Can we diagnose adverse food reactions in dogs and cats with in vivo or in vitro tests?” accessed February 2026, https://link.springer.com/article/10.1186/s12917-017-1142-0

(5) Olivry and Mueller, BMC Veterinary Research, “Discrepancies between ingredients and labeling in commercial pet foods,” accessed  February 2026, https://link.springer.com/article/10.1186/s12917-018-1346-y