I took my 8 week old pup to the vets for her first vacine and the vet said she has a small heart murmur and it may disappear.  Anyone had this? I would just like some reasurance that it may go as she is a cavalier so I understand they can suffer with MVD.  Do they normally disappear?

They can do - but I'm afraid not always. If the parents (and preferably the grandparents) have clear, current heart certificates then the likelyhood is vastly reduced. 'Flow murmurs' are common in young pups and often correct themselves with time.
But
If the pup is from untested stock then the risk is higher, this is why buyers must only buy from breeders who abide by the breeding protocol set down by breed clubs..to include MRI screening for Syringomyelia.

But I'm sure you are now well aware of this since your other dog has SM.

hi ...............its quite common in shelties and usually disappears

I had a couple Boston pups when checked at 7 weeks had it, by the time they were 10 weeks it was gone- Dozer who is 71/2yrs old had one at 7 weeks to but cleared up and it has never came back....

Hindsight is a wonderful thing and I probably shouldnt have got this pup, neither parents were screened however the last pup I did my homework with has SM a disease I knew nothing about at the time but now both me and the bank manager know a lot about. At least no matter what this pup is insured so will get the best treatment, not that my other dog wont as I happily paid for her MRI and will continue paying for all her treatment.  Thanks for putting my mind at rest I am glad others have had disapearing murmurs.

> neither parents were screened