possible heart problems in young rabbit?

Question
I am a breeder and my nearest "rabbit-savvy" vet is over 70 miles away.  I am reluctant to stress this rabbit with a long drive if I can avoid it.

I have a 7 week old baby rabbit that is half flemish giant and half english lop.  His mother's milk never came in and I have formula fed him (with the formula mixture you recommend) since he was a newborn.

For a while he seemed like he would be a runt but was developing ok.  However, now I am very concerned because he does not want to run around like he used to and when I compare him to some 3 1/2 week old flemish babies, he is not much bigger than they are.

My biggest concern is that his torso is almost "barrel-shaped" with stumpy little legs, a small head, and long ears.  If I didn't know better, I would think he had gas (and I have tried to treat him for that).  

But to be honest with yo u- this is more of a "his development is off" type of thing and what I'm suspecting is that he has heart issues or something else that is causing his torso to grow (at least it is larger than it was before) but nothing else is growing.

Have you ever seen this before?  

I am assuming I will lose him within the next week or so - but I was just curious if you've ever seen/heard of this before.

Answer
Dear Peg,

The baby might have some form of congenital abnormality, but whether his heart is involved is anyone's guess.  There are so many different things that can go wrong--chromosomally or developmentally--to produce abnormal phenotype that it's anyone's guess what could have caused this little one's problems.

I hope he does okay.

Dana