I have had Parents tell me that their bully can swim fine, and they could up to between 1 and 2 years of age. Sad to say, those parents lost their bullys to drowning. You may wonder...what happened? Bullys, as they grow, tend to get more dense, thicker bones and muscles, and start to be what I call "Heavy Boned". A lot of times this does not occur until after 1 year of age, thus the sad scenario above....the bully could swim fine until one day it sank and drowned. NEVER take a chance!! It is definitely NOT worth it.