I just got back from picking Tassie up at the vet from her ultrasound to see what was up with her heart murmur. She, of course, did great and everyone loved her and said how sweet she was. But the results weren't the greatest. Luckily, it's not the worst case scenario which I forget what part of the heart that involves, but it ends in surgery. She has a problem with the biggest valve. It's not shutting properly and is letting blood get into the chamber. Over a long period of time, this causes the heart to grow larger and the lining to get thinner and weaken. So the heart would get bigger and weaker. The worst news is that her lining is already thinning, which the vet and the ultrasound dude were surprised at since she's not even 2 years old yet.
The vet was very unsure as to what this exactly means - the fact that there is already a change in her heart definitely didn't give anyone warm fuzzies, and probably means that in another year, untreated, it would be worse, and really shorten her lifespan. He couldn't say that for sure since she is not a pure breed that has history he could go on. He said we can put her on blood pressure medication and this should definitely help the condition from progressing faster than if she wasn't on any medication. I asked why we wouldn't want to put her on the medication and his only reason was cost - so I'm thinking it's way expensive like hundreds of dollars a month, but it turns out it will be more like $30 a month. So I said, GIVE ME THE MEDICATION!!! Seriously, we don't want to gamble with her life over $30/month. So that is good news and I hope that it really does help her heart!
She'll get another ultrasound in a year (and probably every year after that) to monitor what's going on. AND another good thing is he said this should not in any way limit her activities - so she is free to run as much as she wants.