I just purchased a six month supply of Frontline Plus on Ebay from a veternarian.  When I received the product I noticed it was manufactured in Australia.  I compared it to my previous Merial Frontline Plus product, manufactured in U.S.,  and noticed there were discrepancies...so I called the U.S. Merial Technical Info hotline at 1-800-660-1842 and talked to a Merial technical staff member about my concerns.   Merial said that all Frontline Plus products are produced in France, however they are produced in accordance with EACH countries EPA or regulatory commission's guidelines for that particular country (for their particular pests, etc.)  They would NOT agree that the American and Australian product was the same because of this.  They also said they could not guarantee a product manufactured for Australia.  When I asked what were the specific differences, they invited me to write their scientific staff.  I emailed the Ebayer seller, a vet, who insisted both products were the same but agreed to refund my money.  I am now a little wiser and will definitely make sure any chemical product I purchase is for U.S. application, especially on my precious little doggie.