6 month old sheltie with grade 5/6 heart murmur

I have a 6 month old Sheltie named Max. I bought Max from an Amish breeder. I asked him questions and saw the parents...but I guess I didnt ask the right questions. He was around 9 weeks when I bought him, 5 days later I took him to a vet for his first shots. The vet had a hard time listening to his heart and took him in the back room to listen better. She said she thought Max has an echo or possibly a small heart murmur. 2 weeks later I went to get his 2nd shots...same thing happened. She said that she cannot say for sure if it was a murmur or an echo, but if it was a murmur, then he would likely outgrow it. 4 weeks later i took him to a different vet to get his last shots and that vet said Max had a grade 6 murmur and was going to die, possibly of sudden death. I was shocked...going from possibly nothing, to a HUGE deadly murmur. I was devastated, but wanted to go back to the first vet to get a second opinion, That was on the 16th of June. the vet did in fact grade his murmur a 5/6, took an x-ray, saw the enlarged heart and fluid in the lungs and gave him 6 months to live. Max runs around like a normal healthy puppy. He gains weight, eats a lot, no labored breathing, his gums are pink, and hes getting bigger every day. I guess my question is, is there any medicine that i can give him without taking him to a cardiologist, as I just cannot afford heart surgery, and I already know that his heart is bad and I feel like an ultrasound will tell me what I already know. What signs do I need to look for other than labored breathing or coughing? He is a puppy, so he takes naps several times a day, but always loves to play and run. should i not let him do these things? What is the life span of a puppy with a grade 5/6 murmur w/o surgery? Will he get better as time goes on? As Max gets bigger, does it make more room for the enlarged heart? I am going absolutely insane, we love this little guy very much, he is the best dog we have ever had, so smart
Amber and Max

[Kimberly Coyner, D.V.M., DACVD]

All of your questions are best answered by a cardiologist after evaluation of xrays and heart ultrasound, and I recommend at least getting a consultation. They may be able to prescribe medication to prolong your dog's life. Fluid in the lungs indicates heart failure and usually death will occur within a few weeks if untreated.

[Justine Lee, D.V.M., DACVECC]

I would definitely take your dog to a cardiologist - it may be a PDA, which is a congenital defect that is very easy to fix, but expensive. They may be able to give you options. In the least, the cardiologist may be able to help you find someone willing to adopt your puppy and pay for the surgery themselves. I know this is hard, but I also have a cat with a congenital heart murmur (6/6), so know where you're coming from. The lifespan would be POOR and significantly shorter without this potentially life-saving procedure. Also, the longer you wait, the worse the prognosis due to long-term changes to the heart. I'd get this looked at ASAP for your puppy's best outcome. No oral medication would help in this situation if it was a PFA - just catheterization to fix it (or surgery).