Recognizing Food Allergies or Intolerances in Dogs

Does your dog frequently scratch, constantly lick its paws, or experience diarrhea and gas after eating? If so, it’s reasonable to suspect a food intolerance. These symptoms may be signs of a food allergy or intolerance.

However, there may be many other potential causes. Therefore, a definitive diagnosis cannot be made based on symptoms alone. A veterinary examination is essential. If there is reasonable suspicion, an elimination diet must be strictly followed, followed by a controlled provocation test.

Food Allergies and Intolerances: What's the Difference?

These terms are often used interchangeably in everyday conversation. However, medically speaking, they do not describe the same thing.

It is virtually impossible for dog owners to distinguish between the two based on symptoms alone. Therefore, in veterinary practice, the term "adverse reaction to food" is often used initially as a general term.

What symptoms might indicate a food allergy?

Symptoms can vary from dog to dog. Some dogs primarily exhibit skin problems, while others primarily or exclusively exhibit digestive issues.

Possible Skin and Ear Problems

• loose stools or diarrhea
• more frequent bowel movements
• Flatulence
• Vomiting
• Abdominal discomfort
• Weight loss or loss of appetite in cases of more severe or prolonged problems

Important: These symptoms are not specific. Parasites, infections, environmental allergies, sudden changes in diet, and various medical conditions can cause similar symptoms.

Allergies, parasites, or environmental factors?

Itching does not necessarily mean that food is to blame. Other possible causes include fleas, mites, bacterial infections, yeast, contact reactions, and environmental allergens. For non-seasonal itching, a dermatological evaluation may include an elimination diet after other obvious causes have been investigated.

The list of possible causes of digestive problems is also long. A veterinary examination is especially important if symptoms recur or persist for a long time or if there is a change in the dog’s overall condition.

What triggers a food allergy?

In the case of a true food allergy, the immune response is usually directed against the proteins in the food. Generally, a dog can react to a protein source it has consumed before. Therefore, an ingredient is not automatically low-allergenic just because it is high-quality, natural, or commonly found in dog food.

The blanket statement that grains are the most common trigger is also inaccurate. Animal protein sources can be just as relevant. It is impossible to determine which ingredient is problematic for a specific dog based on general frequency lists.

Does "gluten-free" automatically mean suitable for dogs with allergies?

No, gluten-free dog food is not automatically hypoallergenic. Food allergies are often directed against proteins, which can come from animal or plant sources. While a gluten-free diet may suit a dog’s nutritional needs, it is no substitute for a diagnostic elimination diet.

How Is a Food Allergy Reliably Diagnosed?

The most reliable approach consists of two related steps:

1. Elimination diet: For a period determined by the veterinarian, the dog is fed only a carefully selected diet.
2. Food challenge: If the symptoms improve, the previous food or suspected ingredient is reintroduced under controlled conditions. If the symptoms return, this supports the diagnosis.

Improvement during the diet alone does not prove that the dog has a food allergy. It could also result from other changes or occur by chance. An elimination diet followed by a controlled food challenge is considered the most reliable method of diagnosis.

What Type of Diet Can Be Used?

Depending on the dog’s dietary history and symptoms, the veterinarian will generally select one of the following options:

• A nutritionally complete diet containing a protein source the dog has not previously consumed
• A veterinary diet containing hydrolyzed protein
• In selected cases, a professionally formulated home-prepared diet

In hydrolyzed diets, proteins are broken down into smaller components. These diets may be used when an adverse food reaction is suspected.

A home-prepared diet should not be fed over an extended period without professional formulation. It must fully meet the dog’s nutritional requirements.

Why Strict Adherence to the Elimination Diet Is Essential

During the elimination diet, the dog must receive only the prescribed food and approved ingredients. Even small amounts of additional protein sources can make the results more difficult to evaluate.

Common factors that can interfere with the diet include:

• Treats and chews
• Table scraps
• Flavored medications or supplements
• Flavored dental care products
• Food intended for other pets in the household
• Food picked up while outdoors
• Different rewards given by multiple caregivers

Keep a simple journal throughout the diet. Record the dog’s food, stool consistency, itching, skin changes, ear problems, medications, and any unusual events. This will help the veterinarian evaluate the dog’s progress more accurately.

Are blood tests for food allergies useful?

Blood, saliva, hair, and skin tests are sometimes offered as simple allergy tests. However, these tests are not suitable for reliably diagnosing food allergies in dogs. A customized veterinary testing plan combined with an elimination diet has proven to be an effective alternative.

What should you do if your dog cannot tolerate its food?

• Document the symptoms: When do they occur, how long do they last, and what is the dog actually eating?
• Don't change your pet's food randomly: Frequent changes introduce new variables and make it harder to identify the cause.
• Have your pet examined by a veterinarian: Other illnesses, infections, and parasites must be considered.
• Compile a feeding history: Include treats, chew toys, table scraps, medications, and previous types of food.
• Strictly follow an elimination diet: Determine the type and duration in consultation with the veterinary practice.
• Don't skip the provocation test: Only controlled re-exposure can confirm the diagnosis.
• Carefully select long-term food: Once a diagnosis has been confirmed, consistently avoid the identified triggers and ensure that the diet meets the dog’s nutritional needs.

When should you take your dog to the vet right away?

Have your dog examined promptly if symptoms recur or persist for several days. Veterinary care is especially urgent in the following cases:
• Shortness of breath or facial swelling
• severe or repeated vomiting
• bloody diarrhea or blood in the vomit
• significant weakness, circulatory problems, or collapse
• signs of dehydration
• severe pain
• rapid weight loss
• refusal to eat or a significantly altered general condition

What type of dog food is best for dogs with sensitive stomachs?

For an adult dog with a sensitive digestive system, a clearly defined, easily digestible formula is a good option for the daily diet. However, the most important factor is which ingredients the dog can tolerate.
dogdog® Adult Sensitive Lamb & Rice is a gluten-free, complete food for adult dogs. It contains lamb and rice, which are easily digestible sources of nutrients. This product may be suitable for dogs whose needs align with the formula. However, it is not a diagnostic elimination diet and may not be suitable for every dog with suspected allergies. If your dog has recurring symptoms, consult your veterinarian about your dog's diet.

Conclusion

Itching, paw licking, recurring ear infections, diarrhea, or vomiting may be consistent with a food allergy or intolerance, but they do not prove it. Other causes are common and must be considered. Reliable clarity comes not from guesswork or a quick test, but from a systematic approach: a veterinary examination, a strict elimination diet, and subsequent controlled provocation testing. Only then can a dog food that is suitable for the long term be specifically selected.