So if you use ivermectin at a high dose to worm your dog and they already have heartworms it will kill all the heart worms at once therefore it may cuase a blockage in the heart or lungs. I suggest getting a heartworm test done at your vet before starting ivermectin just to be safe and also have them calculate a dose for you. Because the mounthly dose is quite small.
We have used ivermec to get rid of heart worms in three dogs. It takes a while to do it but it works.
Bryant is going to have a heart attack over worming posts..........................