I have a Pug puppy who is about 7 months old. She has shots but I want to begin giving her preventative heartworm medication as soon as possible, but I heard something about having to do it before a certain age... Is that true? I think someone told me that I need to start it by 6 months of age... Will it be just as effective if I start now? I'm hoping it's not true about needing to get it before 6 months... I'm just wondering what the facts are.
Thanks!