My girl Luna is a 16 week old Cane Corso x Pressa Canario. She's coming along nicely and is almost shoulder to shoulder with my adult American Bulldog. The Vet told me she will grow until about 9 months, which sounded rather quick. I expect her to be close to full height by then but not filled out or at full adults weight by then. Having googled it, the general opinion seems to be that a mastiff will grow until 3 - 4 years. Which in turn sounds a little on the long side. When can I expect my big girls to be full Shetland pony sized?