puppy with heart murmur

Question
We have a 10 week old boxer puppy with has been diagnosed with a level 3 (on scale of 1 to 6) heart murmur.  She seems to be too thin as we can see her ribs, although she does eat.  Can this be from heart murmur and what should we be feeding her?

Answer
You should be feeding a puppy chow now and very little else.  Switching to an adult chow for the
larger breeds at 4- 6 months, slows growth and helps develop sturdier
joints.

Your dog definitely should be narrower at the waist than the hips and chest.
You should be able to easily feel the ribs, but not see them.  Each dog is
different.  Standard recommendations are a good place to start, but each dog
must have its food adjusted to its individual needs. Here is a link to a good illustrated guide,
http://www.longliveyourdog.com/twoplus/RateYourDog.aspx

Would she eat more if you gave it too her?  There are some dogs that refuse to eat enough to completely hide their ribs.  What does the vet say about her weight?  If the vet isn't concerned, and she won't eat any more, let well enough alone.