Have you tried looking at some French dog breeds? Like the Grande Bleu De Gascoyne (I can see Lucius with these rather than the deerhounds like Champion Kilbourne Macleod who played Sirius, and his brothers Macbeth and Macdeva were on-set, so presumably Lucius' dogs in the pic.)

French dog names - try French literature - Dartagnan (on the pedigree I linked to) or what about the characters from Les Laisons Dangereuse? Valmont, Danceny, Merteuil, Tourvel.