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Food Allergies and Intolerances in Pets

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Lindsay Butzer, DVM
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Dr. Lindsay Butzer
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Puggle dog licking paws, a common symptom of allergies and food intolerances in pets.

Is your pet struggling with itchy skin, recurring infections, or indigestion? According to the ASPCA, up to 20% of dogs and cats will develop some type of allergy in their lifetime.

But what many of us refer to as “allergies,” may actually be a sensitivity or intolerance. While these terms are often used interchangeably, learning the differences can be critical in helping your pet find relief.

What Are Allergies in Dogs and Cats?

The word “allergy,” specifically refers to an immune system overreaction to a substance.

Allergic reactions happen quickly, as soon as a few minutes after exposure to an allergen.

Leading up to an allergic reaction, the immune system produces IgE (or immunoglobulin E) antibodies, which attack the allergen. This triggers the release of chemicals like histamines. Histamines cause inflammation that manifests as symptoms like itching, swelling, nausea, and gastric upset.

Severe allergies can cause an anaphylactic reaction, a potentially life-threatening reaction that can cause trouble breathing, nausea, vomiting, pain, and swelling. Like people, pets can have anaphylactic reactions to foods, bug bites, or environmental allergens.

What are Sensitivities in Dogs and Cats?

Like an allergy, a sensitivity is an immune system response, but the reaction happens much more slowly, and symptoms may not appear for hours, even days after exposure to a food or environmental trigger.

Sensitivities involve IgG (or immunoglobulin G) antibodies, which cause a delayed reaction and can remain in the body for a long time. In pets with sensitivities, a more subtle reaction can occur, and relief may not be seen for weeks after an environmental or dietary change.

In dogs and cats with sensitivities, symptoms usually manifest as red, itchy skin, hair loss, recurring ear infections, body odor caused by yeast overgrowth, though gastric symptoms like nausea, gas, loose stools, and vomiting can also occur, though symptoms are not life-threatening.

Sensitivities may be a symptom of leaky gut syndrome, a condition in which the lining of the small intestine becomes permeable, possibly due to chronic inflammation. As a result, undigested food particles can enter the bloodstream and cause an immune system reaction.

What Are Intolerances in Dogs and Cats?

Intolerances, unlike allergies and sensitivities, do not directly affect the immune system. Instead, they affect the digestive system, triggered by foods that the body is unable to easily break down.

Lactose intolerance, for example, is associated with the body’s inability to produce lactase, the enzyme needed to break down the lactose, a type of sugar that’s found in most dairy products.

Once weaned, most mammals produce less lactase as it is no longer needed to digest milk. This is why so many dogs and cats, as well as humans, have trouble digesting dairy products after they’re fully grown.

While a food intolerance primarily affects the gastrointestinal system, intolerances may affect other parts of the body, causing symptoms similar to those seen in pets with sensitivities. A compromised digestive system can cause imbalance in gut flora, which may in turn cause itching, yeast overgrowth, recurring infections, and even mood and behavior issues that can improve once the food intolerance is under control.

How Are Allergies, Sensitivities, and Intolerances Diagnosed?

Allergies, sensitivities and intolerances are not well understood, even by medical researchers and veterinary professionals. More research is needed to truly understand the differences between these conditions and even reliably diagnose pets to determine what food and environmental triggers are causing symptoms.

Possibly the most reliable, but also the most time-consuming and intensive way to diagnose food allergies or intolerances in pets is with an elimination diet. With an elimination diet, you’ll eliminate all potential allergens and triggers from your pet’s diet for about six weeks until symptoms resolve. Then, you’d gradually reintroduce foods until symptoms recur.

The 5Strands At-Home Pet Intolerance Test is another option that many pet parents have found success with. With the provided kit, you collect and submit a hair sample to the 5Strands processing center, where it is analyzed for energetic alignments that may indicate imbalances that point to potential food and environmental intolerances.

Your veterinarian can conduct in-office allergy testing using a blood test or intradermal skin testing. These tests are usually recommended for diagnosing environmental allergies, but cannot be used to diagnose food intolerances or sensitivities.

3 Most Common Causes of Allergy Symptoms in Pets

Short on time? Try ruling out the three most common causes of allergy symptoms in pets.

  1. Flea allergy dermatitis (FAD) is the single most common cause of itching in dogs and cats. Many pet parents do not realize their pet has fleas, and in those sensitive to flea bites, even one bite can cause overwhelming itching. Make sure your pet is protected with year-round flea and tick prevention.
  2. Protein sensitivities make up the majority of food-based triggers, with chicken, beef, dairy, and fish among the most common culprits. Switching to a food with an alternate protein source or hydrolyzed protein can sometimes resolve allergy symptoms in pets.
  3. Environmental allergies like grass, mold, mildew, pollen, and household cleaning chemicals are also common in pets. Symptoms that come and go with changing seasons can point to an environmental allergy.

Treating Allergy Symptoms in Dogs and Cats

While we have more questions than answers when it comes to allergies in pets, there’s still hope. You can help your pet feel better with itch relief sprays, shampoos, and skin and coat supplements, as well as probiotics and digestive aids to relieve gastric distress.

Symptoms of allergies, intolerances, and sensitivities can be nonspecific, and can be similar to those of other conditions including bacterial skin infections, parasites, and endocrine disorders. The first step you should take to helping your pet feel better is talking to your vet.

Consult your veterinarian or make a same-day virtual vet appointment with VetLive.