"Leashed" means to tie or secure something, usually an animal, with a long, thin rope or strap called a leash, to ensure it doesn't run away or get lost.
So if you want your pup to be comfortable going on leash walks on the street, this needs to start early as well. (drjensdogblog.com)
Have you ever come across off leash dogs on your walk? (grishastewart.com)
I used a shock collar on her to deter her from unwanted behaviors as well as to help with off leash training (again, wasn't needed for my golden). (caninejournal.com)