Puer canem suum vocat.

Because canem is the accusative singular form, and it is the direct object of vocat.

In this sentence, the boy is doing the action, and the dog is receiving it. Latin shows that with case endings:

• puer = nominative singular, the subject
• canem = accusative singular, the direct object

The dictionary form is canis (dog), but after a verb like vocat (calls), Latin uses the accusative: canem.

Because puer is in the nominative singular, which is the case normally used for the subject of a sentence.

Latin often tells you who is doing the action by the word ending, not mainly by word order. Here:

• puer = subject
• vocat = he calls
• canem = object

So puer is the one doing the calling.

Because suum has to agree with canem, not with puer.

Latin adjectives, including possessives, agree with the noun they describe in:

• gender
• number
• case

Here canem is:

• masculine
• singular
• accusative

So the possessive must also be masculine singular accusative:

• suum

If the noun were nominative masculine singular, you would get suus instead.

Yes, that is often the best way to understand it.

Suus, sua, suum is a reflexive possessive, meaning it refers back to the subject of the clause. So in this sentence, suum means his own, referring back to puer.

So the sense is:

• the boy calls his own dog

This helps distinguish it from possession belonging to someone else.

Because suum refers back to the subject, while eius usually refers to someone else.

Compare:

• Puer canem suum vocat. = The boy calls his own dog.
• Puer canem eius vocat. = The boy calls his / her dog, meaning the dog belongs to another person, not to the boy himself.

This is an important Latin distinction that English often leaves unclear.

Vocat is:

• 3rd person singular
• present tense
• active
• indicative

It comes from the verb vocare, meaning to call.

So vocat means:

• he calls
• or she calls
• or it calls

In this sentence, because the subject is puer (boy), it means he calls.

Yes.

The Latin present tense often covers both:

• simple present: calls
• progressive present: is calling

Which English translation sounds best depends on context. Without extra context, either can be correct.

Because Classical Latin does not have articles like English the and a/an.

So:

• puer can mean the boy or a boy
• canem can mean the dog or a dog

Context tells you which is meant.

It matters less in Latin than in English because the endings already show each word’s job.

So all of these could mean roughly the same thing:

• Puer canem suum vocat.
• Puer suum canem vocat.
• Canem suum puer vocat.

However, word order can still affect emphasis and style. A very common neutral prose order in Latin is often subject + object + verb, which is what you have here.

You know because of agreement.

Both canem and suum are:

• masculine
• singular
• accusative

That matching tells you they belong together: suum canem = his own dog.

Latin often uses agreement to show which words connect, even if the word order changes.

A little, yes.

Puer is a second-declension masculine noun, but unlike many second-declension masculine nouns, its nominative singular does not end in -us.

For example:

• servus = slave
• amicus = friend
• but puer = boy

So puer is a normal dictionary form, but learners often notice that it looks different from the more common -us pattern.

They are:

• puer, pueri = boy
• canis, canis = dog
• suus, sua, suum = his own / her own / its own / their own
• voco, vocare, vocavi, vocatum = call

Knowing the dictionary form helps you recognize how the sentence forms are built:

• canis → canem
• suus → suum
• vocare → vocat

A common classroom pronunciation would be roughly:

POO-er KAH-nem SOO-um WOH-kaht

More carefully:

• puer = POO-er
• canem = KAH-nem
• suum = SOO-um
• vocat = WOH-kaht

Pronunciation varies somewhat depending on whether someone is using reconstructed Classical pronunciation or a later school/church tradition, but that is a good starting point.