Immunotherapy & Allergy Testing
In animals with a confirmed diagnosis of environmental allergies, we often recommend allergy testing in order to create immunotherapy (allergy shots or drops) as a treatment for them.
Intradermal Allergy Testing (IDAT)
Intradermal or “skin prick” testing is the preferred method since we are testing the affected organ. Certain drugs, like steroids and antihistamines, need to be stopped for a period of time prior to skin testing. Animals are sedated, the hair is clipped on one flank, and 50 allergens are injected into the skin (indoor and outdoor, house dust mites and pollens in particular). Positive and negative controls are used to gauge the response. Saline is used as a negative control since it has no allergenic properties. Histamine is used as the positive control since it reliably causes an allergic reaction. Allergens are compared to the controls. A subjective scale(based on size, redness, and firmness) is used.
Serum Allergy Testing
For some patients, a blood test may be more appropriate. In cats, subtle skin test responses are more common, so we usually start with blood testing and circle back to skin testing if needed (i.e. few or no positives on the blood test). Other reasonsfor starting with or only performing a blood allergy test: high risk with sedation (due to age/illness or brachycephaly,i.e. smush faced) or patient is on medications that cannot be stopped and wouldinterfere with IDAT.
Common Misperceptions
- Testing for the purposes of avoiding allergens is neither recommended nor successful since our pets don’t live in sterile laboratory environments - Allergens are in the air and can never be fully avoided!
- Environmental allergy is a diagnosis of exclusion. This means that we will have already made/confirmed this diagnosis PRIOR to pursuing testing.We do not do this test to “see if your pet has pollen allergies” - It is a"treatment test" and not a "diagnostic test" - we formulate treatment with the information obtained.
- The only way to diagnose food allergy is with a food trial. Skin or blood testing for food allergy has been repeatedly shown to be invalid. The results from those tests do not correlate with confirmed food allergy (many false positives and negatives) or with each other (extreme differences between companies mean none are accurate at this time).
- Saliva/hair testing for any allergy has been shown to also be invalid - the laboratory used for allergy testing is very important regarding ability to trust the results. Heska, Idexx and Nextmune are the laboratories that we work with.
