Ha, my mom just sent me this:

Notice leash. Headed for door, went out a ways, then ran back in so fast the leash dropped out of my hand. Then she tore around the whole house a couple of times then landed in a dining room chair without hanging herself somewhere on the leash. So we took the harness and leash off. We’ll practice more another day.

This cat, btw, is named Baby Huey.  She’s huge.  Mom just calls her Baby.