heart murmur in puppy

Just been told by vet,
  2 male  cairn pups have a low grade heart murmur.  (grade 1.)
They are 6 weeks old.
Is this an  inherited thing ?
Also told it  could fix itself at next vacc. at  9 weeks  would this be the case
Never struck this before   with this breed in 20 years
any help woud be welcome

  

[Jim Humphries, B.S., D.V.M.]

Murmurs may or may not be congenital but when we see them in such young pups it is high on the list.  I have seen "functional" murmurs occur in young pups that do seem to spontaneously resolve over time - perhaps several months.  

At this point you should simply follow this murmur with more frequent veterinary exams.  Simple ascultation (listening with a stethoscope) will tell you a great deal.  If it were to increase in grade them I would worry about a congenital defect and you can proceed with x-rays and ultrasounds, ECG etc.  

good luck