How Much Vet Care Is Enough?

JPUPPY asks: "How much veterinary care is reasonable and how much is too much? I just took one of my 4 dogs in for a check up and was told she now has a heart murmur (she's 10 years old). The vet told me she might need heart medication and certainly needed lots of tests. $500 later, x-rays and blood tests all showed totally normal, but the vet wanted to have an EKG for another $300. All for a dog who apparently feels fine. I feel guilty for hesitating to run more tests, but money is definitely an issue. How are we supposed to know how much to do for a pet?"