We currently have Mac on Sentinel but yesterday we found a tick on him. My husband wants to use Frontline. The vet said we should switch him to Interceptor and add Frontline. Any suggestions? I know alot of you prefer natural products. My husband is not real keen on that idea thinking they won't work as well. Does Interceptor work as well as Sentinel (i know it doesn't do anything for fleas whereas Sentinel starilizes (sp) them.)? What about Frontline vs. Advantage?