Has anyone tried Trifexis.  What are the thoughts out there on it?  My vet recommended it.  They are currently on Heartgard and Comfortis.  It would be great if I could give only one pill to them.  They always seem a little down after taking their meds.  I am worried on whether or not it really works for heartworm.  Several years ago I had a dog that the vet put on Revolution, at that time it was the new rage on an all in one.  My poor chow mix ended up with heartworm.  After that, the vet…