Many pets suffer recurrent skin problems
relating to allergies. Allergic reactions are
caused by overzealous response of the body’s immune system to a
foreign substance (antigen). Frequently, the instigating factor(s)
in allergic reactions can come from the food we are feeding our
pets. When the immune system is exposed to
certain foods, it may produce antibodies directed against that
substance. On repeated exposure, these
antibodies cause the release of chemicals that cause the allergic
symptoms. In most cases, the offending antigen
is related to the protein component of the food. Certain ingredients
in pet food are more digestible than others. Feeds that have lower
digestibility leave more residues in the intestine that may promote
allergic reactions. For the most part, no one
food is known to be more “allergenic” than another.
However, since many pet foods contain similar ingredients
(corn, soy, wheat, beef, chicken) if may appear as if these items
are more frequently related to allergies.
The symptoms of food allergies mimic those of
inhalant allergies. In fact, many pets that have
food allergies will also have inhalant allergies and vice versa.
The following is a list of the common symptoms seen with food
allergy dermatitis.
Most often, there is no real seasonal change in the
symptoms of food allergy (unless the pet also has inhalant allergies).
How do we diagnose food allergies?
Diagnosis of food allergy is not a simple matter.
While there is a blood test that purports to test for this
problem, it has not been shown to be reliable and is therefore not used
frequently. The only way we can truly tell if a pet
is food allergic, is to use an elimination diet. This means that we must
eliminate all the foods that the pet has been accustomed to eating and
replace them with a new diet that is less likely to be allergenic.
An ideal “non-allergenic” diet would consist of highly digestible
feeds to which the pet has never or rarely been exposed.
The body’s immune system is very effective at
recognizing foreign proteins. However, it has been
shown that if the protein molecules are small enough (less than a
molecular weight of around 8,000 Daltons), the immune system will ignore
the protein and not make a response to it. Based on
this information, Hill’s Pet Nutrition has developed two
diets that we employ to both test and treat suspect food allergic pets.
These diets are called Z/D (for zero antigens) and
Z/D ultra. In both of these diets,
Hill’s has taken the protein components and broken them down
(by a process called hydrolysis) into fragments that are smaller than
the 8,000 Dalton threshold needed to produce an allergic reaction.
In the Z/D product, potatoes are used
as the carbohydrate source since most pet foods do not contain potatoes.
In the Z/D ultra, even the carbohydrate source has
been broken down so that there are no protein fragments larger than
6,000 Daltons.
When we are attempting to make the diagnosis of
food allergy, we feed only the Z/D or Z/D ultra
diet. No treats, table food, snacks etc will be given during the first 2
months of the diet challenge. If the symptoms
improve or disappear during this elimination trial, we have good
evidence that the problem is food related. If we
want to be certain, we can re-introduce the original food to the pet and
observe for recurrence of symptoms. The itchiness will usually recur
within a week or two.
How do we treat suspect food allergies:
Once the diagnosis of food allergy has been made,
we generally continue feeding the Z/D diet to avoid
further allergic symptoms. Sometimes we can try alternative feeds that
do not have any of the ingredients found in the original offending diet.
Unfortunately, pets that have a tendency to food allergy may
become allergic to any of the new diets unless they have the unique
protein components found in the Z/D diets.
shipped to us. Because there
are no preservatives in the serum, it must be refrigerated and there is
a very small chance of infection associated with the injections.
You will be taught proper technique in handling the serum, which
should minimize this risk.
What do we do to take care of my pet’s skin
problem while the food trial is proceeding?
During the original elimination diet trial, we will
use various drugs and products to help relieve your pet’s suffering and
clear up pre-existing lesions. These drugs typically may include
Prednisone (a form of cortisone), antihistamines,
medicated shampoos and conditioners, and
essential fatty acid supplementation.
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