Macbeth represents a pug because they can be risky but once they get caught or realize their mistakes, they feel guilt and sorrow just like when he and Lady Macbeth planned to kill Duncan in Act II because before Macbeth actually killed Duncan, he felt guilt and wanted to back out. After he killed Duncan, he says, "What hands are here? Ha! They pluck out mine eyes! Will all great Neptune's ocean wash this blood Clean from my hand?" in this quote he is explaining that even when he washes off the blood from his hands, the memory will stay with him forever on how he took someones life.
Lady Macbeth represents a turtle because she is very strong and has a thick layer until she reaches her "soft spot". Throughout Act II, she was getting very angry at Macbeth for not being a "man and sticking to his word" on killing Duncan, so she makes up a spiteful plan to obtain making sure Macbeth gets his place as King. After Macbeth killed Duncan, he felt sorrow and remorseful and told Lady Macbeth that he is ashamed of what he did and he will not live life like it is supposed to be because of the sin he made and her response was to man up and forget what he did because what happened, happened.