Food allergy

In animals as in humans, food allergies manifest as different clinical diagnoses. It can be manifested as purely IgE-mediated diseases (like urticaria, angioedema and anaphylaxis), purely cell-mediated diseases (with eosinophils or lymphocytes, such as inflamatory bowel disorders) and as both IgE and cell-mediated, which based in evidence, it seems to be the case for food-induced atopic dermatitis.

Prevalence of food allergy

The true incidence of food allergy is still not entirely clear, but has been reported to range between 10% and 25%, in dogs with allergic skin disease. It is also estimated to be around 1/3 of dogs with atopic dermatitis. It is described a stronger incidence in dogs under 1 year of age or above 6 years old.

Labrador retrievers, West Highland White Terriers, Boxers, Rhodesian
ridgebacks and Pug breeds are some of the breeds predisposed to developing food allergies. The most common described allergens responsible for food allergies in dogs are beef, chicken, egg, milk, wheat, soy and corn.

Clinical signs

The most common symptoms are dermatological or gastrointestinal (or a combination of both).

Dermatological signs are varied, and often indistinguishable from those associated with atopic dermatitis.

Gastrointestinal symptoms may include vomiting, diarrhoea, weight loss, abdominal discomfort, flatulence and frequent defecation (more than three times a day).

The most common symptoms are dermatological or gastrointestinal (or a combination of both). The dermatological signs are varied, and are often indistinguishable from those associated with atopic dermatitis. When pruritus is not responsive to corticosteroids, a food allergy should be considered. However, if pruritus responds to corticosteroids, that does mean that no food allergy is present.

Generalised or localised non-seasonal pruritus (of the face, ears, paws, armpits, inguinal and perineal regions) is the most frequently described symptom. The patient experiences severe itching, resulting in excessive and unnatural scratching, biting and licking.

It is also possible for the effects of a food allergy to be below the “itch threshold”, with only flare-ups of pruritus occurring when there are increased levels of environmental allergens during the high-pollen season. Otitis externa and recurrent pyoderma, with or without pruritus, has also been associated with food allergies.

Gastrointestinal symptoms may include vomiting, diarrhoea, weight loss, abdominal discomfort, flatulence and frequent defecation (more than three times a day).

Inform owners about how allergens can be found in more than just the feed
Treats are a common villan when an elimination diet is unsuccessful

Diagnosis

Food allergy represents an etiologic diagnosis, both in animals and humans, with different clinical diagnoses. It can be manifested as purely IgE-mediated diseases (like urticaria, angioedema and anaphylaxis), purely cell-mediated diseases (with eosinophils or lymphocytes, such as inflamatory bowel disorders) and as both IgE and cell-mediated, which based in evidence, it seems to be the case for food-induced atopic dermatitis.

Serum tests are only designer to reveal IgE sensitisations to allergens, including food allergens, therefore, such tests cannot predict cell-mediated diseases.

IgE-mediated food allergies are those in which signs occur within the first hours after an allergen ingestion (i.e., challenge).

Lymphocyte-mediated diseases occur days after a challenge.

In recent studies on food allergen characterization, there was a very good correlation between IgE serology to the food allergen and the positive reactions that occurred early (i.e. less than 12 hours) after a challenge with that same allergen.

Food elimination trials

The diagnosis is confirmed by the recurrence of clinical signs when the food that was given previously is reintroduced to the diet.

If the patient’s symptoms improve during the elimination trial, the next step is to “challenge” the patient with the food and ingredients received previously.

During an elimination trial, the patient must not receive any other food, treats, leftovers, medications, vitamins, or supplements that contain protein other than the one chosen for the trial.

Pet Allergy Xplorer (PAX Food)

PAX is the first commercial serological IgE-specific test that uses allergen extracts and molecular components to identify which allergens are affecting pets.
Molecular allergology is a state-of-the-art approach to the detection of sensitisations, whereby defined single allergen components are used for the determination of specific IgE in place of traditionally-used allergen extracts.
The molecular components are purified or recombinant proteins that provide a higher level of standardisation than allergen extracts and enable a more precise identification of IgE sensitisations.

While there is no doubt that the current testing of food allergens has not been sufficiently predictive of food allergy to justify their use in clinical practice, the use of molecular allergology warrants to reevaluate this position.
There is evidence that food allergies—an etiologic diagnosis—represent, in fact, a group of clinically and pathogenically different entities, from the IgE-mediated urticaria, angioedema and anaphylaxis to the cell-mediated gastro-intestinal diseases; food-induced atopic dermatitis likely involving both mechanisms.

IgE sensitization tests, are only designed to detect the sensitizations of IgE- mediated food allergies, which are those with signs recurring within the first hours after an oral food challenge. As such, the PAX offers an attractive solution to detect IgE sensitizations to molecular food allergens, which should prove of help to select allergens for oral food challenge and/or to select food ingredients unlikely to cause immediate reactions.

SOLO®

SOLO is a mono-protein feed for dogs and cats that can be used to identify food allergy or food sensitivity, as part of an elimination trial, or to provide a protein source as part of a home-made diet.

It can also be used for patients convalescing after surgery, for tube feeding, for picky eaters, or as an addition to other food to increase protein intake.

It contains no additives, colouring agents or preservatives and has a palatable flavour.