The object of this article is a type of phraseological unit, namely expressions. The aim of the study is three-fold: 1) to analyse the importance of the semantic field of animals in the phraseological creation of languages and more specifically in expressions; 2) to prove that phraseology is one of the most difficult aspects of language to translate; 3) to contribute to the creation of an auxiliary tool for translators of Galician and other languages so that they can introduce a phraseology in their work which is not dependent of Spanish and has complete sociocultural connotations.