Be careful and you should consider talking to your vet about the dose you are giving. I am glad this dose didn't hurt your dog but you are giving over 33x the amount of ivermectin that is in a heartguard tablet. The standard dose for humans, pigs, horses and other livestock is
200 micrograms / kilogram. That works out to a dose of 0.9 ml of the 1% injectable per 100 pounds. This is the standard dose humans take.
But, as I mentioned, dogs are much more sensative and according to the heartguard product insert the dose for dogs is
6 micrograms / kilogram. That means a 100 pound dog should only get 0.027 ml. My dog was about 45 pounds so I would need 12 microliters which is a small amount that you need a specialty microliter syringe if you want to give the recommended dose.
https://heartgard.com/sites/default/...Plus_PI_BI.pdf