I have used interceptor three times and I didn't see anything with my puppy but I had to go back to Heartguard with my older one becuase she has been battling digestive issues and I didn't want to add anything in that could irritate her. She did have it once in the spring and it MAY have affected her because when she took it for the first time, she had an episode of intestinal upset. I really couldn't say it was the interceptor because it was almost three or four days after she took it when she wasn't feeling well. But since she's so sensitive, I went back to Heartguard just in case. |