Food allergies also leave animals suffering, says study

24 Aug 2017 --- Humans are not the only ones to suffer from food intolerance and allergy symptoms like swelling in the face or an asthma attack. Other animals, such as cats, dogs and horses, are affected after feeding as well, according to a new study by the Messerli Research Institute, a cooperation between the University of Veterinary Medicine Vienna and the Medical University of Vienna. In fact, the number of pets affected by food allergies and intolerances has even converged with that of humans.

The institute has now condensed the knowledge about human and animal food allergies and intolerances into a new European position paper. The paper highlights the strong similarities in animal and human symptoms and triggers of adverse food reactions. The publication also stresses the importance of more comparative studies on the mechanisms and the diagnosis of food intolerance, and on formulating adequate measures.

Overlap in symptoms and triggers
“Not only humans but basically all mammals are susceptible to developing allergies, as their immune system is capable of producing immunoglobulin E,” explains lead author Isabella Pali-Schöll. Normally, these special antibodies help defend parasites or viruses. They are also responsible for type I allergy symptoms, which are the most well-known and immediately-occurring symptoms and include hay fever, allergic asthma and anaphylactic shock. In the field of nutrition, there are also very common non-immunologic forms of food intolerance, like lactose and alcohol intolerance, the University of Veterinary Medicine Vienna notes.

The position paper, primarily written by Pali-Schöll and Erika Jensen-Jarolim, shows that the symptoms of food intolerance are similar in both animals and humans. One difference, however, is that in the case of dogs, cats or horses, the adverse reactions mostly affect the skin, followed by the gastrointestinal tract. “Asthma or severe shock reactions have rarely been observed in animals,” notes Pali-Schöll.

There are even overlaps in the triggers of immune responses to certain foods and ingredients. Pets may suffer from both lactose intolerance and outright milk protein allergies. Some mammals also have allergic reactions to certain proteins in wheat, soy, peanuts, tree nuts, fish, eggs and meat.

Underdeveloped allergy diagnostics
Precise knowledge about the active molecules of the allergens helps assess the risks of severe reactions, especially with food allergies. Many of these allergenic molecules that affect humans have been identified and are already used in diagnostics like the allergen microchip test. As far as animals are concerned, the University of Veterinary Medicine Vienna says there is still a big need for research.

Similarly, a precise and comprehensive diagnosis is essential for establishing adequate measures against food intolerance. But many mechanisms and triggers for animals have not been sufficiently researched, in part because some test samples or substances are not even available.

Avoiding allergens remains best option
A so-called elimination diet is a prerequisite for correctly diagnosing both animals and humans, the University of Veterinary Medicine Vienna notes. This regimen means removing all sources of protein from an animal's diet. “During this period of diagnosis, the animal will be fed homemade food or diet food prescribed by a veterinarian. Only then, and if there have not been any dangerous allergic reactions before, can ‘normal’ food be gradually reintroduced,” advises nutrition scientist Pali-Schöll. With this diagnostic procedure, the allergen-free diet can be tailored to the food intolerance of the animal or human while also avoiding unnecessary restrictions.

A thorough comparison of adverse food reactions in humans and animals offers insight into the risk factors for the development of the condition, and can thus lead to improved recommendations for the prevention and treatment of adverse food reactions in animals and humans, the university’s press release points out.

At the moment there are no therapies for humans and animals, but many new variants of immunotherapy have entered trial phase. “As for the so-called sublingual and epicutaneous immunotherapy, which is treatment under the tongue or on the skin, respectively, the first few trial phases have already achieved some success. But it will take several more years for any products to see market launch and standard application,” says Pali-Schöll.

The European position paper, “Comparing immediate-type food allergy in humans and companion animals – revealing unmet needs,” was published in the Allergy journal and can be found here.