I believe that they have pretty much hit full height at 9 months to 12 years, but do not have full muscular development for about another year. Our trainer does not recommend a lot of low jumping or any high jumping at all until at least 18 months. I may be off -- someone will correct me if I am. :)
Heather, Mommy to skinkid Toby and Furkids Sir Wally of Pugzu and Duke Leto Prancypants the Fragrant.
Also Mom to Just Dakota the Canadian X gelding; pudgy budgies Kiwi, Fidget and Bree plus rescue budgies Spud, Minty, and Wendy. Stepmom to Monty Python.
Main squeeze of high school sweetie Scot.