An allergy is an immune system reaction to a specific molecule, which is
called an allergen. Most allergens are proteins, but practically anything can
become an allergen in any particular animal. In dogs and cats, the most common
allergy is to flea bites; followed by “atopy” an allergy to inhaled particles
such as pollen, mold, and dust mites.
The medical name for an allergy is a “hypersensitivity reaction.” There are
four types of hypersensitivity reactions, but most of the allergies our pets are
prone to are Type I or “immediate” hypersensitivity. This reaction takes place
quickly; usually within minutes, but up to about 12 hours after exposure. An
allergy to bee stings or flea bites are classic examples, but food allergies and
atopy also fall into this category. Some allergies are very severe and can be
life-threatening, though this is rare in pets.
The symptoms of allergies in pets usually appear in either the digestive
system (vomiting and/or diarrhea) or the skin (itchiness, redness, lesions, hair
loss, ear infections). It can be very difficult to distinguish atopy from food
allergies; and some pets have both.
In this article, we’ll focus on food allergies
Skin symptoms of allergy (referred to as “allergic dermatitis”) are
frequently complicated and aggravated by secondary infections by yeast or
bacteria. Additionally, these symptoms may not be related to food or allergies
at all; there are many potential causes of digestive and skin issues. If your
pet is having problems, please have your veterinarian take a look.
develop over time and after multiple exposures to the allergen, although they
are occasionally seen in young puppies and kittens, or after only one or two
exposures. It’s common to think that if a pet has been eating the same food for
years, symptoms couldn’t be due to allergies. But just the opposite is true:
eating the same food over a long period of time is a recipe for allergy
development. Not surprisingly, then, the most commonly used pet food ingredients
are the ones pets most commonly become allergic to. For instance, meat
by-products, liver, and meat-and-bone meal come largely from cattle, so
allergies to beef are common.
Pets Most Common Food Allergens Dogs Beef, chicken, milk, eggs, corn, wheat, and soy Cats Fish, beef, milk and milk
products Some animals have cross-reacting allergies; that is, if they are
allergic to chicken, they are also allergic to turkey, eggs, and other birds; a
beef-allergic pet may also react to other cloven-hoofed animals such as bison,
venison, or lamb. Pets who have an allergy to one thing are prone to developing
Comedian Chris Rock was once talking about friends whose child
had food allergies, and asked, “How can anyone be allergic to food?”And that’s a
good question! All animals must eat to live, so it doesn’t exactly make
biological sense that the body would reject good nutrition, or react so badly to
One way that an ingredient can become an allergen is the heat processing
that pet food undergoes during manufacturing. Heat can “denature” proteins,
which means that it distorts their shape. Shape is how the immune system tells
proteins that belong in the body apart from foreign proteins. When an abnormal
protein is picked up by an immune cell, the whole system responds, and
antibodies are produced. After that, every time that protein appears, antibodies
flock to it and stimulate inflammation. The more damaged proteins, the more
inflammation. When the offending allergen is in the pet’s everyday diet, the
situation can become quite severe and uncomfortable for your companion.
The very fact that this reaction takes place at the lining of the gut causes changes in
the lining itself. Swelling and inflammation cause the normally tight barrier of
gut lining cells to become “leaky.” This “leaky gut” will absorb more things it
shouldn’t, causing the reaction to move into the bloodstream, where it can cause
inflammation elsewhere, notably the skin.
Allergies are harder to deal
with, but the treatment for food allergies also happens to be one of the
simplest ways to diagnose them. Changing your pet’s diet to a “novel ingredient”
diet, also sometimes called a “hypo-allergenic” diet, allows the immune system
to settle down and the inflammation to resolve. The new diet should contain
protein and carbohydrate sources that the animal has not had before. Here’s how
to do a “diet trial” for food allergies:
b. Use one of the many ready-made commercial pet foods that can be used for a novel ingredient
Choose an unusual protein such as rabbit, bison, and duck, with a carbohydrates
like sweet potatoes, brown rice, and green peas. There are veterinary diets for
this purpose, but their ingredients tend to be poorer quality than a good
natural food brand.
d. Consider a raw diet. As with dry and canned foods,
sometimes animals who are allergic to an ingredient in a processed pet food will
readily tolerate the same ingredient in its raw form. However, in pets with
leaky gut syndrome, the natural bacteria in raw meat may be a risk. You can
lightly cook the food for a while until the gut has healed.
2. In most cases,
it’s best to switch diets gradually over a week or two. Cats are notoriously
finicky, and it may take even longer for them. If your pet is willing to eat the
new food right away, you can make the change faster, but be aware that digestive
symptoms could get worse at first, because the gut has not had time to adjust.
3. Feed exclusively the new food for at least 8 weeks. No cheating—o table
scraps, no treats. Giving anything but the new diet will put you back to square
one, and you’ll have to start the 8 weeks all over again.
symptoms may take up to 12 weeks to resolve, but there should be at least
noticeable improvement within about 8 weeks.
4. If the symptoms aren’t changing
at all, you may need to switch to a different diet. Remember that allergies can
cross-react, and that your pet may be allergic to more than one ingredient.
There are also several supplements that can be very helpful for allergies. These
can be used independently or in conjunction with a diet trial.
2. Probiotics are
“friendly bacteria” that are important for gut function and health of the cells
that line the digestive tract. They also have some anti-inflammatory properties.
Remember that allergic pets tend to
develop more allergies—including to new foods. Lamb and rice was once a popular
combination for allergic pets, but after eating it over a long period of time,
many pets became allergic to lamb, too. If your pet is prone to developing
allergies, it’s wise to switch foods (to different protein and carbohydrate
sources) every 3 or 4 months to prevent future problems.
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Instead, the content offers the reader information and opinions written by our staff,
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