Jennifer, is Iverheart a soft "treat" type of chew, or a tablet? If it's a tablet, and if it's scored (ie if there's a line running down the middle), then it is safe to halve and/or quarter the dose. As a former nurse, I was taught that only scored tablets could be safely divided for dosing, because the medication amount is constant throughout the pill. As Karen mentioned, that's unfortunately not always the case though with non-scored tablets or chew type medications. We had to switch Chica from Heartgard to Interceptor, because she had a seizure after her first Heartgard dose
, due to ivermectin sensitivity. I sure hope Novartis starts Interceptor production again though, because I was only able to get a 6 month supply from the vet, and it was the last box he had left! It's getting harder and harder to get nationwide.