OK.

I've put Dog in the cage. But when I ask him to fix the wires or whatever, he says he's hungry!
And that he would like to hear ''Master's voice''...

What should I do?

did you play the tape?

here is a great resource for FNV: http://fallout.wikia.com/wiki/Portal:Fallout:_New_Vegas

Go on your pip-boy.

Data - Notes - Dog Command Tape.