Bruno needs Heartworm Treatment

My little guy was found chained to a fence eating scraps in Louisiana. He was rescued and sent to Ohio. When I saw him, I fell in love. It wasn't until after I signed the adoption papers that I was told he's heartworm positive. I am a widow on a fixed income and this is a very costly process. I've managed to get him through the process, however, his last visit confirmed he is still heartworm positive with larvae. He only needs one injection which is $300. He's so close to the finish line. Please help us. He is definitely a fighter and such a good boy. Please help me get him healthy so he can live a life of being safe and loved.