Today's Parola del Giorno is the verb sguinzagliare, which means to unleashor to let loose.
See the verb used below in its context:
La nuova legge impone ai proprietari di sguinzagliare i propri cani solo nelle apposite aree nei parchi.
The new law requires owners to unleash their dogs only in the special areas in the park.
And of course there is also the noun "guinzaglio" (meaning leash). Given the form of "add s to a verb to make it 'un'", you MIGHT think that there is also a verb "guinzagliare" (to put on a leash), but in fact there is not. There is the adjective "guinzagliato" (leashed), but to say "to put a dog on a leash" you'd say "mettere il guinzaglio al cane" or "legare il cane col guinzaglio." To have a person on a leash: "tenere qc al guinzaglio." There is no verb guinzagliare.