Heartworm prevention is very important. I used to live in Oklahoma, where heartworms were very uncommon and didn't require prevention as much. So, when we moved to Florida, we didn't think at all about heartworm prevention, and my puppy, Thunder (13), started having convulsions and seizures. We took him to the vet, and it was discovered that he had heartworms. They think he was having seizures because one may have been lodged in his brain. They had to do a reverse, which is killing the babies first, then the adults, because his case was so severe. After they finally killed all the heartworms, after having to suffer so much watchin my puppy suffer so very much, he developed congestive heart failure due to the fact that the worms had expanded his heart, and now they were gone. And the worm, though dead now, still was in his brain. He still had seizures... certain things triggered them... sunlight, drinking when he came in... he lost almost all control of his bladder, and his stool was so runny we had to wash him off everytime he went. A short time later he died. He was a wonderful puppy, and I'll never forget him. I just wish I would've known the pain he would've gone through, and the threat that was there. I am an aspiring veterinarin, and I was a vet tech. I tell everyone I know that say they have dogs to put their dog on heartworm prevention, even if I don't know them.
Now, my sister found a stray who looks like a brown version of my Thunder puppy. He has heartworms. He's only about three, and his case isn't bad, so his chances are good. He's such a sweetie. He only likes me and my sister right now. Poor guy... it's very obvious that he's been abused a lot.

But he's taking a liking to me and my sister.
If you would, pray for him to be okay through his heartworm treatment.