O cachorro latiu, mas o gato não miou.

O is the masculine singular definite article, meaning the.

So:

• o cachorro = the dog
• o gato = the cat

Portuguese often uses definite articles in places where English might or might not use them, so having o here is completely natural.

They are in the simple past, more specifically the pretérito perfeito in Portuguese.

In this sentence, they describe completed actions in the past:

• latiu = barked
• miou = meowed

So the sentence is talking about what happened: the dog barked, but the cat did not meow.

They are the third-person singular past forms of the verbs:

• latir = to bark
• miar = to meow

Conjugation here:

• latir → ele/ela/você latiu
• miar → ele/ela/você miou

So:

• O cachorro latiu = The dog barked
• O gato miou = The cat meowed

These forms match he/she/it in English, but in Portuguese they also work with noun subjects like o cachorro and o gato.

Portuguese does not use a helper verb like do/did for negation.

Instead, the normal pattern is:

• não + verb

So:

• não miou = did not meow
• literally: not meowed

This is very common in Portuguese:

• Ele não falou = He didn’t speak
• Ela não saiu = She didn’t leave

Mas means but.

So here:

• O cachorro latiu, mas o gato não miou.
• The dog barked, but the cat didn’t meow.

This is different from mais, which means more.

Compare:

• mas = but
• mais = more

This is a very common mix-up for learners because the words look so similar.

Because mas joins two contrasting clauses:

• O cachorro latiu
• o gato não miou

In Portuguese, it is very normal to put a comma before mas, just like in English before but when joining two full clauses.

So the punctuation here is standard and natural.

A simple Brazilian Portuguese approximation:

• não ≈ now, but with a nasal sound
• latiu ≈ lah-CHEEW in many Brazilian accents
• miou ≈ mee-OW

A few notes:

• não has a nasal vowel, which English does not really have in the same way.
• In many Brazilian accents, ti before an i sound becomes something like chi, so latiu often sounds like la-CHIU.
• miou has two vowel sounds together and is stressed on the last part.

The tilde in não marks nasalization.

So ã is not pronounced like a normal a. Air comes through the nose as well as the mouth. The tilde is an important spelling mark in Portuguese and changes the sound of the word.

In não, it helps produce the nasal sound that makes the word distinct.

Because Portuguese does not need a subject pronoun when the subject is already stated.

Here, the subjects are clearly named:

• O cachorro latiu
• o gato não miou

So adding ele would be unnecessary.

Portuguese often avoids repeating subject pronouns when the meaning is already clear.

Yes, but the meaning and tone can shift a little.

Both can mean dog, but in Brazilian Portuguese:

• cachorro is the everyday, most common word
• cão can sound more formal, literary, or appear in fixed expressions

So in a simple sentence like this, cachorro is the most natural choice for everyday Brazilian Portuguese.

Yes, very similar.

The basic order is:

• subject + verb
• subject + não + verb for the negative clause

So:

• O cachorro latiu = The dog barked
• o gato não miou = the cat did not meow

That makes this sentence quite beginner-friendly, because its structure is close to English.