My Vet says to start HW prevention before the 6 months age. Make sure your dog is a breed that can take ivermectin .......When using Ivomec as a heartworm preventative, how early can you start giving this to puppies or what is the earliest age you can give the Ivomec to a dog?
I have always started mine between 4 mo. and 5 mo. of age and have had no problems.
If you need help with dosing please post back or pm me.
Best , oldhounddog