Jen, I'm so sorry to hear about Willow's heart murmur. I sure hope it's nothing serious or at least treatable. I also believe in taking all of my cats to the vet for an annual exam and their shots. I feel it's better to be safe than sorry. Although I hate to go to the doctor, I also go every year to get my pap smear, mammagram, and every other year I have my cholesterol done. My father also has a slight heart murmur and it wasn't detected until he was in his late forties. One of my doctors also detected a slight heart murmur in me. My current doctor hasn't detected one so far.

I believe that not all heart murmurs are always detected and some are so small that it's almost impossible to hear them. I think I've also heard that people can outgrow them but I'm not sure this is true. My point is that even if you did take Willow to the vet last year, the vet may have not been able to detect his heart murmur. Please take care and keep us updated on Willow's condition.