Εμβολιάζω το κατοικίδιο.

Because Greek usually does not need an explicit subject pronoun. The verb ending -ω in εμβολιάζω already tells you the subject is I.

So Εμβολιάζω το κατοικίδιο naturally means I vaccinate / I am vaccinating the pet.

You can add εγώ if you want emphasis or contrast:

Εγώ εμβολιάζω το κατοικίδιο.
= I’m vaccinating the pet.

It is:

• present tense
• active voice
• 1st person singular

So it means I vaccinate or I am vaccinating, depending on context.

Greek present tense often covers both the English simple present and present continuous.

It can mean either one.

Greek present tense does not force the same distinction English does. So:

• Εμβολιάζω το κατοικίδιο can mean I vaccinate the pet.
• It can also mean I am vaccinating the pet.

Context tells you which reading is intended.

Yes. Greek verbs are normally listed in dictionaries in the 1st person singular present, so εμβολιάζω is the dictionary form.

It is related to εμβόλιο, meaning vaccine.

A useful related form is εμβολιάζομαι, which means I get vaccinated / I am vaccinated.

κατοικίδιο is neuter singular here, so it takes the neuter singular article το.

So:

• το κατοικίδιο = the pet

This is the normal noun used for pet in Greek.

Yes, that is a good observation. It originally functions as an adjective meaning something like domestic or kept at home, but in everyday Greek it is very commonly used as a noun meaning pet.

You can think of it as a shortened form of:

κατοικίδιο ζώο
= pet animal

In normal speech, το κατοικίδιο by itself is completely natural.

It is in the accusative case because it is the direct object of the verb εμβολιάζω.

In this sentence, I am doing the action, and the pet is receiving the action.

A detail that can confuse learners: for many neuter singular nouns, the nominative and accusative forms look the same. So you identify the case mainly from the noun’s role in the sentence, not from a visible ending change.

Greek uses the definite article more often than English does.

So το κατοικίδιο is very natural when you mean a specific pet, or the pet being discussed.

If you leave the article out, the meaning usually changes. For example:

• Εμβολιάζω το κατοικίδιο. = I vaccinate the pet.
• Εμβολιάζω κατοικίδια. = I vaccinate pets.

So the article helps show that we are talking about a specific, identifiable pet.

Yes. Greek word order is more flexible than English word order.

The most neutral version here is:

Εμβολιάζω το κατοικίδιο.

But you could also say:

Το κατοικίδιο εμβολιάζω.

That version is more marked and gives extra emphasis to the pet, something like It’s the pet that I’m vaccinating.

So the original order is the most straightforward and neutral one.

A rough pronunciation guide is:

Εμβολιάζω ≈ em-vo-LYA-zo
το ≈ to
κατοικίδιο ≈ ka-ti-KI-thi-o

A few helpful notes:

• The stress in εμβολιάζω falls on -λιά-.
• The stress in κατοικίδιο falls on -κί-.
• The letters οι are pronounced like ee, not like English oi.
• The Greek letter δ sounds like the th in this, not the th in thin.

You would say:

Εμβολιάζω το κατοικίδιό μου.

That means I vaccinate / I am vaccinating my pet.

Notice the written accent in κατοικίδιό μου. That extra accent appears because of the possessive μου.

This is a very useful variation, since in real life that is often what a speaker means.

Then you would normally use the passive form:

Το κατοικίδιο εμβολιάζεται.

That means The pet is being vaccinated or The pet gets vaccinated.

So the difference is:

• Εμβολιάζω το κατοικίδιο. = I vaccinate the pet.
• Το κατοικίδιο εμβολιάζεται. = The pet is vaccinated / is being vaccinated.