Latir vs. ladrar
Both latir and ladrar translate to to bark in English and describe the sound made by dogs. They are synonyms, but the primary difference lies in regional preference—Brazilian Portuguese versus European Portuguese—and the level of formality.
Latir
A2This is the most common verb used in everday Brazilian Portuguese. While it is fully synonymous with ladrar, latir is the standard choice for casual conversation in Brazil. In very rare or poetic contexts, it can also refer to the beating of a heart (similar to latejar), but its primary usage is for dogs.
O cachorro começou a latir quando a campainha tocou.
(The dog started to bark when the doorbell rang.)
Não gosto quando os cães da vizinhança decidem latir à noite.
(I do not like it when the neighborhood dogs decide to bark at night.)
Se ele latir mais uma vez, vai acordar o bebê.
(If he barks one more time, he will wake the baby.)
Ladrar
B2This is the standard term used in European Portuguese (Portugal) for everyday speech. In Brazil, ladrar sounds formal, older, or literary, and is rarely used in daily conversation. However, ladrar is preserved in almost all Portuguese-speaking regions within specific proverbs and idioms.
Cão que ladra não morde.
(A barking dog does not bite.)
Os cães de guarda costumam ladrar para qualquer estranho.
(Guard dogs usually bark at any stranger.)
Ouvimos a raposa ladrar na floresta.
(We heard the fox bark in the forest.)
Summary
Use latir if you are speaking Brazilian Portuguese. Use ladrar if you are speaking European Portuguese or quoting the famous proverb cão que ladra não morde. Regardless of which you choose, native speakers from all regions will understand the meaning.