I've wanted to do this last year, but never got the chance, so here goes...
Somebody on YouTube just posted the original opening and closing titles from the 1942 Tom and Jerry cartoon
Dog Trouble, sourced from a very good condition nitrate print, and this proves that it was indeed the very first MGM cartoon to have that red "An MGM Cartoon" card at the beginning:
http://www.youtube.com/watch?v=zk5egCBTqZoOh, and one more thing...
APRIL FOOLS! (Yes, these aren't the actual original titles, but I assume this is probably what they would have looked like.)