Yes he did discuss how we could find out. Firstly he said from his experience the majority of dogs allergies are more environmental issues (pollen, dust, seasons) than food. He said he would estimate that only about 20% of cases are food issues. However, he said this is not to say this is not Bobby's problem. From what I understand, he is trying out the course of antihistamines to see is it seasonal related. If it goes away then Bobby might need a course once or twice a year. If this doesn't work he said we can do allergy testing. From these results we can try eliminating certain foods etc and if this isn't successful they can create tablets based on what the allergy test results. This he said only has a 50% success rate according to seminar he attended recently. Then he said if that doesn't work we could try Atopica.
You might find Monica Segal's latest newsletter, which is on trying to treat this problem and find the source of allergies, helpful:
The dog she is referring to is her cavalier.
Thanks so much for that Karlin. Great article with lots of helpful tips. His bedroom will soon be cleaner than mine :p.