Iris waits at the Rainbow Bridge...did Trifexis kill her?

My family is grieving. Iris left us suddenly this week after a sudden and brief illness. This is her story as told by our Mom. Nothing will bring Iris back, but please give a second thought before you switch to Trifexis, a new heart-worm preventative that just came on the market this year.

from Pam Monahan: Iris suddenly became very ill last week with intestinal issues. She was treated twice at our regular vet; once for diarrhea and then for vomiting, lethargy, not eating. Her lab results came back normal except for her thyroid, which was very low. She started medication for low thyroid, but then starting vomiting. She had been at the emergency vet for two days of tests. She had many tests performed there, including 2 ultra sounds and a barium swallow. They could find nothing wrong; no blockage, no foreign object, nothing. She lost 6 pounds in a week. She worsened overnight and when we visited with her this morning we made the decision to let her go and were with her when she passed. We had given Iris and Ivy a dose of Trifexis, a heart-worm preventative/flea control medication on November 29 and Iris became ill the next day. That is when we took her to our vet. So, a week and a day later, a dog that was fine and loving life, is gone. The ER Vet initially was skeptical of my concern about this heart-worm preventative medication, but did immediately perform a necropsy, at our request. She saw no evidence of advanced cancer, but did send off tissue samples for analysis. And, she herself contacted the manufacturer of Trifexis and Iris has a case number. It certainly would have been easier if she had been eaten up with cancer or even swallowed something. So, now we are involved with a pharmaceutical company, Elanco (Eli Lilly). Just want to ensure that this does not happen to other dogs.
We are broken hearted.