I don’t have any experience with this, but I know it’s the most common form of canine heart disease. Canine heart disease usually develops slowly, so one important question is whether your baby has symptoms or whether the heart murmur was found during a routine exam.
Here is a fairly extensive article about it, which includes possible treatments. Not all dogs need treatment immediately, though, if they don’t have symptoms.
https://vcahospitals.com/know-your-p...isease-in-dogs