My 4 yr old pup just got diagnosed with heart worms even though i have the vet receipts to show I have had him tested every year and negative. And the vet gives a shot once every 6 months to prevent. Pup has been coughing more and more so took him in. First they thought it was trachea problem. Then they checked out his lungs. Have any of you ever been through this? My neighbor told me it's not cheap and the dog can still die. Should I let them give him the needle z or spend 1000 ...side note I am from Iowa.