i have a eight week old king charles spaniel with a heart murmur .
what should i do

Was it the breeder or the vet that told you about the heart murmer???

Well depends on you? Did you buy the puppy from the breeder knowing this? If your vet has pointed this out to you you have two choices.
1.You can go back to the breeder and asked for a full refund .Has the puppy sold was not healthy and had a default.
2.If you decide to keep the puppy tell the breeder the problem and say can you get some sort of refund
You can live with a dog with a heart defact

Hi dont panic a lot of pups have a murmur at this age which is why it is called a puppy murmur when you go back for next vac. it should be gone some times it is there a bit longer but very weak your vet should have told you this.

My Tibetan Mastiff bitch (Thea) was diagnosed as having a heart murmer and she led a foll happy active life for 12 years.