I tried Comfortis in October 08 after not having success with Frontline Plus.  I have 2 poodle mixed dogs and one Brittany.  I gave them Comfortis about 3:30 pm.  Around 5 pm, the Brittany vomited but didn't seem sick.  I put my pets outside and watched them for a while and left them out for about 15 minutes.  When I went back out, my little "Blue" was lying in the grass.  He did not respond when I called his name.  He was very limp when I picked him up but he was alive.  My regular vet was closed by this time and called the emergency vet.  They said lethargy was a side effect.  By this...