I work in a vet clinic and I haven't heard of any of our patients having a reaction to Trifexis. With that being said, I trust Heartgard more just because it's been around for so much longer. I have also given Trifexis when we get free samples with no problems though. I will say though if you don't trust Trifexis, you may not want to give Comfortis either. It has the same ingredient in it (spinosad) as Trifexis for killing fleas. |