Skin Tests Used to Find Causes of Allergy

One of the biggest problems with having pets in the home is the fact that so many people suffer an allergic reaction to them. Though when the allergy first appears it may not be obvious as to what is the cause and all possibilities need to be looked at before being certain that it is due to the pet. This can be a serious problem for the health of the person suffering from the allergy and possibly the thought of having to remove the pet from the family is one that is unbearable. The next steps would be to seek medical advice so that the real cause can be found.

If the allergy is displaying itself on the skin of the patient the then one of the many tests that are used in finding the cause is the skin test. This is usually done after a careful history of the patient has been made to find out if there is any pattern or family history of the allergy, or the likelihood of it occurring just after the pet appeared. It may sound horrifying to the sufferer of the allergy but it is very effective at finding out exactly what substance is making their body react in such a debilitating way. Of the skin allergy tests there are two types, the epidermal and the percutaneous.

Epidermal Skin Allergy Tests

The epidermis is the skin that we all see, the outer layer of our skin that gets exposed to the world and protects us from it. The first type of these is simply the Patch Test, in which suspect substances are placed against the skin and held next to it by a patch. The patch when removed about 20 minutes later will show if the epidermis has reacted to the substance and displaying any skin allergy.

Another is the Friction Test, which is useful with substances like animal hair, where it is rubbed over the forearm about 10 times to see if a reaction takes place.

Percutaneous Skin Allergy Tests

Percutaneous in this case means getting underneath the outer layer of skin and applying the substance there. This is not so bad as it sounds but requires the skin to be pricked or scratched to be able to do it effectively. The first of these tests is the Prick Test, where the substance is placed upon the skin and with something similar to a needle the skin is pricked to see if a reaction forms. There should be no bleeding; it is not a deep prick but just enough to get underneath the surface. The results of this should be seen after about 15 minutes when the substance is washed away.

Another form is the Scratch Test, where the skin is scratched, again not enough to cause any bleeding and only about 5mm long. The substance may be made into a solution to enable it to have contact with the skin, but then it is given time to see if a reaction takes place.

The final skin test here is the Intradermal Test, though this is one that can be difficult to interpret. This is where a very small sample of the substance is made into a solution and injected with a small syringe and needle. This is not the same as having an injection because it is only done just under the surface of the skin, just enough to produce a tiny bump, about 3mm on the surface. This test may take a lot longer to get the results from, in some cases over weeks but is used only in specific situations where any of the other tests above cannot work. If a reaction has taken place the area where the substance was injected will flare up.

These are the most common types of skin test used and many of the simpler epidermal ones are likely to show where the allergic is coming from. It may be the case in pet allergy that the exact cause of the allergy is found and some remedy or solution will be recommended rather than the undesired removal of the pet.