Once diet has been altered based on allergy testing, elimination diet or random choice, it may take as long as two months to see the benefit.  If a longer period has passed and your pet is still scratching, it is time to look further.  If skin scrapings, fungal (ringworm) cultures, yeast preps and other diagnostics have not been performed, it is time to do these now.  It may also be time for some general diagnostic laboratory tests such as blood chemistry and blood counts as well as thyroid evaluation.  As previously mentioned, any number of disease conditions can manifest themselves in the form of skin disease.  If all of these lab tests return with normal results, then it is very possible that the basis for your pet’s itchiness is allergic.  Just as in the chance of any one of many dietary components being implicated in diet related skin disease,  any one of thousands of potential environmental allergens can likewise affect your pet.  Contact agents that your dog or cat touch such as wool, cotton or fill material used in beds can contribute to the discomfort.  Inhaled substances such as ragweed, grass or plant pollen, weed spores are but a few of the many materials that can cause symptoms.  How can we determine which of these substances are relevant to your pet?  Once again allergy testing comes to our rescue.  There are two types of allergy testing currently being offered.  One is known as intradermal testing (previously patch testing ).  In this method  a series of minute amounts of specific allergens are injected just under the skin of the pet and the skin’s response is noted.  It may be done in one or two sessions depending on the patience of the pet.  In the other type of allergy testing, as was mentioned in an earlier post with regards to food, a blood sample is taken and sent out and evaluated for a   antibody reactions to particular substances. This is often known as RAST testing.  It depends on your veterinarian which method is used as there are advantages and disadvantages to both. In the final in this series of posts on dermatology we will discuss how to evaluate the results of this testing and how to use it to bring relief to your pet.