Never mind --- I 'googled' it and found that there can be side effects, although very rare. Obviously, our dog had one of those rare side effects and I won't be giving it to him again.

I originally got it for our other dog who had a bad case of hot spots that we thought might be due to flea allergies. Still, I don't think I will be giving her another dose either and will see if she breaks out again. Since she had no reaction to the Advantix, I will continue it with her if it looks like she has a problem without it for the next two months.