[Maximo]

Welcome to Yorkie Talk. I am very sorry to hear that the Trifexus made Abby Rose sick, and I hope she recovers completely quickly.

I thought Trifexus has Comfortis in it -- or one of the flea & tick oral preventatives. For others reading, definitely check with your vet because there would be no need for doubling up.

I hate giving this stuff to my pups too, but the risk of heartworm is even scarier. You and I both live in the very high risk zone. I decided to give my guys the preventatives year round because the weather is so unreliable and there are really only 2 - 3 months out of the year that we could maybe skip. Then we would have to have blood tests done before re-starting.

We used Interceptor before production was halted, and we are hoping for it to return soon. In the meantime, we are using Heartguard Plus with no problems. I would try that with Abby Rose.

Best wishes.