Learn Italian: Scusa, il gatto è tuo? - Excuse me, is the cat yours?

Scusa is the informal way to say "excuse me", used when talking to a friend, a child, or someone your own age. If you were asking a stranger or someone older, you would use the formal Scusi.

Does tuo end in "-o" because the person I am talking to is male?

No, possessive words in Italian always match the object being owned, not the owner! Since gatto (cat) is a masculine singular noun, you use tuo. If you were asking about a female cat (la gatta), it would be tua, regardless of who you are speaking to.

I learned that Italian uses words like il or la before possessives. Why isn't it è il tuo?

You are right that Italian usually puts "the" before possessives (like il tuo gatto). However, when the possessive comes right after the verb "to be" (è) to mean "is yours" or "is mine", we normally drop the il or la. You can just say è tuo.

There is no question word at the beginning. How does Italian form questions?

In Italian, you do not need to change the word order or add helper words like "do" or "is" to ask a question. The statement il gatto è tuo (the cat is yours) becomes a question simply by raising your tone of voice at the end of the sentence.