A similar expression to this is: "a leopard never changes its spots".
Notice that both of these sayings feature two different animals?
When we talk about a person who finds it difficult to change their way of doing something, we often refer to them as 'a creature of habit'.
Hi
I've just found this website which looks very interesting for my needs of improving my English.
I know a proverb in French like this one but with a monkey and faces... Then I felt in the horses's trap.
I recently realised with an ipad and a translator that I have difficulties to formulate corrects sentenses (by the place of a verb, articl, subject... Must normally be).
We can't teach a monkey faces... By looking on dog's proverb above, it makes me thinking about the circus, which if I am not wrong a very old way to do it in Europe.