DIETARY ALLERGIES IN DOGS AND CATS
Any foreign substance that breaks into the body is normally rejected. That is what happens when you prick yourself with a thorn, or in case of organ transplantation. It is the immunitary system, which is in charge of defending ourselves against any external aggression, that is responsible for these reactions. Happily, the body is normally able to make a difference between foreign substances essential for life, and others that threaten its integrity. This is why we usually tolerate very well the differents kinds of foods composing our diet.
For allergic people and animals, the tolerance is more selective: some foods are not “ recognized ”, and abnormal reactions arise. Dietary allergies are usually directed against the proteins of specific ingredients.
Symptoms of a dietary allergy
A dietary allergy is first characterized by intense itching. The animal itches so much that he mutilates himself, inducing severe lesions. In dogs and cats, the most affected areas are the head, the ears, the neck, and forelimbs. Sometimes, digestive troubles are observed: diarrheas, vomiting, abdominal pain…
Dietary allergy diagnosis
Dietary allergies are rare diseases: they would represent less than 10 % of allergies in general, and they would be responsible for about 1 % of cutaneous problems in dogs and cats. Allergy is often confused with dietary intolerance. This is also an adverse reaction of the body to an ingredient or a food additive, but it does not involve the immunitary system. For example, it may be:
- a milk or a cereal intolerance due to a lack of the specific enzymes (lactase or amylase), necessary for the digestive process;
- a reaction linked to direct intake of pro-inflammatory substances, without any previous sensibilisation period (i.e: histamine in low quality ingredients);
- excessive fermentation in the large intestine, inducing the release of toxic substances (i.e: very low-digestibility proteins)…
To start pointing out an allergy, the clinical signs must be associated with the ingestion of a special type of food. To investigate it, the animal is fed “ an elimination diet ”, or “ hypoallergenic diet ”, exclusively composed of a restricted number of ingredients that are not present in the usual diet.
As lamb meal is uncommonly fed to pets by their owners, it is often proposed for such diets. It does not mean, however, that an animal cannot progressively become allergic to lamb meat proteins, it has already been seen… Moreover, in “ lamb (and rice) products ”, the lamb is usually not the single source of proteins. This type of products is helpless for the diagnosis and the treatment of dietary allergies.
In case of allergy, cutaneous signs disappear within 1-3 weeks in 25 % of cases, 4-6 weeks in 50 % of cases, and sometimes, 9-10 weeks are even necessary. The cat answers quicker than the dog. Even if itching disappears, allergy will be confirmed only if a “ provocation test ” is performed. Progressively, each of the previous ingredients likely to be responsible of the allergy is reintroduced. Normally, a setback of the clinical signs must happen within 1-2 weeks.
All the most common ingredients of pet’s diets are likely to cause an allergy problem. The most often involved food products are: chicken, beef, fish, egg, milk, wheat (in irish Setter), soy… 60 % of allergic dogs react to more than 2 different proteins.
This protocole is quite long and disappointing for the owners who often refuse to step back to identify the specific allergen, when a new diet brings satisfying improvement. Then, some immunologic tests can be proposed, but they are not yet reliable.
Treatment of a dietary allergy
The animal must be fed a diet free of the proteins causing the allergy. However, let’s point out the fact an animal can get sensibilized again towards one of the components of the new diet. The whole thing is then to be done again…
Dietary allergy is an uncommon problem, and it is very difficult to identify it precisely. In most cases, this is a dietary intolerance, and switching to a higher quality food makes the cutaneous and/or digestive troubles disappear.
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