How are food allergies diagnosed?
Reliable diagnosis of allergies, especially food allergies, is far from an exact science. Neither the skin tests which inject antigens into the skin and look for reactions, nor ELISA (enzyme-linked immunosorbent assay) or RAST (radioallergosorbent) tests which detect antigen-induced antibodies in the dog’s blood, have proven to be accurate or reliable–false positives and false negatives are common (again, especially when used for determining suspected food allergies).
If food allergies are suspected, a more accurate test is the food elimination test, but this is not the easiest of tests to perform either: a) Most foods contain multiple ingredients and it is almost impossible to isolate the one offending food source. b) Many food sources (corn, for example) are found in a great number of foods, oftentimes hidden as filler. c) Since it takes four to eight weeks to eliminate a food source from the dog’s system, the total food source elimination testing needs to continue for at least this long–far too long for most folks (or their dogs) to endure.