Re: Animal artists ... where to sell limited edition print
If I were her, I'd google "Saint Bernard" and try to find a St Bernard oriented bulletin board or e-mail list to try to market this. Purebred dog stuff generally sells better to fanciers of that breed than to people interested in art.
If she's not in a rush, she might also check to see if there is a printed breed magazine for Saint Bernards (I'd ber surprised if there isn't). Might be worth putting a classified ad in something like that, but probably take a few months, so not a good option if she wants to sell fast.