Yes. There are different types. Mostly it is related to overall interaction with humans, but can be more or less when talking about stranger versus family/owner interactions. As far as I know Estrelas will test you, but will understand and respect a strong leader. Sao de Miguels are a bit more testing from what I understand. I know a person who expressed caution about handler redirection. Most of these breeds are a bit rank. It is part of being a good guard. I thought one of our Presa owners here had one on those breeds as well. I could be wrong though...