Learn Italian: Il veterinario spera che la cura funzioni.

The verb spera (from sperare, to hope) expresses a desire. In Italian, verbs of hope, wish, or desire trigger the subjunctive mood in the following clause whenever the subject changes. Here, the vet is doing the hoping, but the treatment is doing the working.

Why does funzioni end in -i? Isn't funzionare an -are verb?

Yes, funzionare is an -are verb. In the present subjunctive, the vowel endings swap: -are verbs take an -i ending for all singular forms (io, tu, lui/lei). So, che la cura funzioni is the correct third-person singular form.

In English we say "The vet hopes the treatment works". Can we leave out the che in Italian?

No, unlike in English where the word "that" is often skipped, you cannot drop che in Italian when linking a main clause to a subjunctive clause. You must always include it.

Why use funzioni for "works" instead of lavori?

In Italian, lavorare is only used when a person or animal is physically or mentally doing a job. When talking about a machine, a system, or a treatment being effective or operating correctly, you must use funzionare (to function).