Small and large dogs run on different clocks
The reason one young dog is finished while another of the same age is still visibly growing is mostly body size. A small breed has a short distance to travel to reach her adult frame, so her growth plates close and her height settles relatively early. A large or giant breed has far more skeleton to build, and her growth continues over a much longer period, with the biggest breeds still adding frame and then muscle well into young adulthood. This is also why two puppies in the same training class can look like different life stages despite sharing a birthday. Comparing your dog to a neighbour's dog of a different breed is therefore almost useless, while comparing her to her own measurements from a few months ago tells you exactly where she is.
What finished actually means in the body
Growing happens in stages, and they finish at different times. Height is usually the first thing to level off, as the growth plates at the ends of the long bones close and the legs reach their adult length. After height settles, many young dogs continue to fill out: the chest deepens, the head broadens in some breeds, and muscle develops over the shoulders, back and hindquarters, so the dog's weight and shape keep changing even though the measuring stick says she is done. A young dog in this filling-out stage often looks less gangly and starts to move with more coordination and strength. When vets talk about a dog being skeletally mature, they are talking about those growth plates closing, which is the milestone that matters most for exercise, feeding and decisions such as neutering timing.
Signs growth is slowing in your own dog
You can read the trend at home with simple, regular checks. Measure her height at the shoulder against the same door frame or wall mark every few weeks, and weigh her on the same scale at a similar time of day. When several measurements in a row barely change, height growth has effectively finished, even if she still looks youthful. Notice proportions too: puppies and adolescents tend to look leggy, narrow and slightly too big for their paws and ears, while a finishing dog's body catches up with itself. Keep the numbers dated and together rather than relying on memory, because growth slows gradually and the plateau is much easier to see in a written series than in the dog you look at every day.
Why the endpoint matters for food and exercise
Knowing whether she has finished growing changes practical decisions. Puppy food is formulated for building a body, so a dog who has plateaued usually needs a planned move toward adult feeding and portions watched more carefully, while a large-breed youngster who looks enormous may still genuinely need her growth diet. Vets often time certain conversations, including neutering and joint care, around skeletal maturity, which is one reason breed and size feature so heavily in their advice. If you are unsure where your dog sits, ask at her next routine visit and bring her measurements, because a vet who can see her growth curve can give a far better answer than one working from her age alone.
Keep her growth story in one place
Recording her height, weight, food changes and the point where her growth levelled off gives every professional who sees her the same clear picture, whether that is her usual vet, a trainer planning her exercise, or a boarder feeding her while you travel. Store that growth record in her KinsLe Pet Passport, where her records sit together in one portable packet ready for vet visits and handoffs, so the question of whether she has finished growing is answered from her own documented history.