How do you explain to a 10 year old about religion/evolution?

my 10 year old lad asked me "who made dog's",my first answer was "god",he said god don't exist,(i'm not religious as such,but let the kids make their own minds up that way) so i said evolution single cell beings blah,blah,blah.who made them blah,blah,blah,big bang etc.who done that?its got to a point where i am stumped(as everyone is),next move please?