Once again I can not stipulate enough, how important it is to not over exercise your puppy!
Growth plates are probably the one thing that owners forget to think about. This image below is something everyone should see.
8 - 10 week old puppy xray - notice how far apart the bones are
When you get your 8 -10 week old puppy, PLEASE keep this image in mind. Their bones do not even touch yet. They plod around so cutely with big floppy paws and wobbly movement because their joints are entirely made up of muscle, tendons and ligaments with a skin covering. Nothing is fitting tightly together or has a true socket yet.
When you run them excessively or don't restrict their exercise to stop them from overdoing it during this period, you don't give them a chance to grow properly. Every big jump or excited bouncing run causes impacts between the bones. In reasonable amounts, this is not problematic and is the normal wear and tear that every animal will engage in.
But when you're letting your puppy jump up and down off the lounge, the bed or stairs, or take them for long walks/hikes, you are damaging that forming joint. When you let the puppy scramble on tile with no traction you are damaging the joint.
Symptoms of Growth Plate Injuries
Symptoms may include but are not limited to:
Swelling
Pain
Lameness
Depression
Lack of appetite
Stiffness of the limb
Abnormal bone conformation (abnormal angle, abnormal length)
Early development of osteoarthritis
You only get the chance to grow them once. A well built body is something that comes from excellent breeding and a great upbringing - BOTH, not just one!
So, When Do Puppy Growth Plates Close?
In general, growth plates close when the dog fully matures (usually around 12 to 18 months of age). At that point, the fast multiplying cells have already filled the entire soft area and that area has become a stable bone part.
In simple words, the term "growth plate closing" means ossifying or transforming into bone tissue. The growth plate therefore continues to add to the length of the bone up until the age at which it's genetically programmed to close.
The Five-Minute Rule
This rule was invented to provide pups with age suitable exercise regimens while preventing unwanted injuries.
The five-minute rule states that every puppy should be assigned with five minutes of physical exercise (twice a day) per month of age. The rule applies for puppies and young dogs that are still growing. Once fully grown, they can be physically active for much longer.
Following that rule, a one-month-old pup should have two, five-minute lasting sessions of physical activity per day. A two-months-old pup should have instead two, ten-minute lasting sessions of physical activity per day, while a three months old pup can be physically active for 15 minutes, twice a day.
Last but not least, it is worth mentioning that by physical activity I mean lead walking, NOT ball chasing, NOT playing with older dogs and definitely NO running in the park.
Once grown you will have the rest of their life to spend playing and engaging in higher impact exercise. So keep them calm while they're still a little baby puppy and give the gift that can only be given once.
8 - 10 week old puppy xray - notice how far apart the bones are
A bit of back-story behind these xrays: This is a baby puppy (not Amstaff) who had a knock to his elbow and wasn't using it properly, so he was taken to the vet. There is nothing wrong in these x-rays, thankfully it is a soft tissue injury and he is expected to be fine.