Ah, vets, actually. Give them an insecticide to eat to kill heartworms. OK, it’s a small dose. Give it to them monthly with a dose designed to go up to 45 days (or longer if they’re at the low end of the weight). Give it to them year round even though heartworms are only a danger during mosquito season. Then up the power to last 12 weeks and wonder why problems start happening.
Oh, and give a medicine with a slight side-effect of seizures to a breed with a higher than normal incidence of seizures. That’s DVM.
Very unfortunate situation.