We've been using Sentinel for several years for our dog, and it has worked great. It's convenient and easy to use - just put it in dog food or give it like a treat. We used to live in Texas where fleas and heartworm were a problem, and she's never had a problem with either. No side effects.

I have used another brand when I could not get Sentinel. My dog did not like it and to get her to take it I had to put peanut butter on it. Now that we can get Sentinel again our dog loves it and it makes giving it to her a lot more enjoyable. It works very well and does not make her sick when given to long after she eats. The price was better than any other sites I have found.