Flea, tic, worm = bath before spot on. Athena had a reaction to the spot on. She was sick once on the settee and then into my hands as she was on the bed. She was making the typical, human like, I’m probably going to vomit noise. She then had diarrhea the following day. We bathed her in mild water to open her pores up and it made it easier to separate the hairs by her neck. Looking it up, these reactions are quite common so keep checking your pup.