What are allergies, and how do they affect dogs?
One of the most common conditions affecting dogs is allergy. In the allergic
state, the dog's immune system "overreacts" to foreign substances (allergens
or antigens) to which it is exposed. These overreactions are manifested in three
ways. The most common is itching of the skin, either localized (one area) or
generalized (all over the dog). Another manifestation involves the respiratory
system and may result in coughing, sneezing, and/or wheezing. Sometimes, there
may be an associated nasal or ocular (eye) discharge. The third manifestation
involves the digestive system, resulting in vomiting or diarrhea.
Are there several types of allergies?
There are five common types of allergies in the dog: contact, flea, food,
bacterial, and inhalant. Each of these has some common expressions in dogs,
and each has some unique features.
What is food allergy?
A food allergy is a condition in which the body's immune system reacts adversely
to a food or an ingredient in a food.
What foods are likely to cause an allergic reaction?
Any food or food ingredient can cause an allergy. However, protein, usually
from the meat source of the food, is the most likely offender. Proteins commonly
found in dog foods are derived from beef, chicken, lamb, and horsemeat.
Isn't a lamb-based dog food supposed to be hypoallergenic?
No, although many people think it is. Several years ago there were no dog
foods on the commercial market that contained lamb. A manufacturer of prescription
dog foods formulated a food from lamb that was suitable for allergy testing,
which will be explained below. Because of that situation, lamb-based dog food
was considered "hypoallergenic".
Dogs are not likely to be born with food allergies. More commonly, they develop
allergies to food products they have eaten for a long time. The allergy most
frequently develops in response to the protein component of the food; for example,
beef, pork, chicken, or turkey. Food allergy may produce any of the clinical
signs previously discussed, including itching, digestive disorders, and respiratory
distress. It is recommended to test for food allergy when the clinical signs
have been present for several months, when the dog has a poor response to steroids,
or when a very young dog itches without other apparent causes of allergy. Testing
is done with a special hypoallergenic diet. Because it takes at least 4 weeks
for all other food products to get out of the system, the dog must eat the special
diet exclusively for 4-8 weeks (or more). If positive response occurs, you will
be instructed on how to proceed. If the diet is not fed exclusively, it will
not be a meaningful test. If any type of table food, treats or vitamins are
given, these must be discontinued during the testing period.
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