When do Australian Kelpies stop growing?

​​Australian Kelpies stop growing and reach their full adult size between 12 to 18 months of age. Individual dogs will vary, of course, and some Australian Kelpies can continue to fill out and develop muscle mass up to around two years of age. Proper nutrition, exercise, and veterinary care during their early growth period will ensure the health and well-being of your Australian Kelpie as they reach their full size.