Check out the X-ray image below of a 3 week old puppy.
Look at how far apart the bone growth plates are!
Growth plates are regions of cartilage that sit at the ends of the long bones. The growth plates are vulnerable to being injured and potentially fractured because they are the last portion of the bones to harden are.
As a puppy grows and develops, moving, stretching and working their muscles, hormonal changes trigger cartilage to calcify and develop into a denser harder matter. These plates contain rapidly dividing cells that allow bones to become longer until the end of puberty. Growth plates gradually thin as hormonal changes approaching puberty signal the growth plates to close and connect the bones.
A dog’s long bones do not develop from the center outward; instead, growth occurs right by the growth plate at the end of the long bones. The main problem is the fact that an injury to a growth plate may result in damaged cells that will halt growing on one side. In the meantime, the healthy, undamaged cells on the opposite side will continue to grow with the end result of the bone developing a deformity.
This X-ray vividly depicts why you should never permit puppies to jump, walk up/down stairs, over-exercise or over-train. Any type of high-impact activities or prolonged exercise on hard surfaces can potentially stunt the puppy’s bones, cause them to cease growing or grow in a crooked or misshapen way. 
This includes repetitious jumping to catch a Frisbee, jogging on concrete and hurdling full speed over or around obstacles with leg twisting movements. Further, puppies should be picked up and handled very carefully during this time as well. Doing too much activity or being incorrectly lifted while a puppy’s bones are still growing could cause dislocations, muscle tears as well as serious bone issues later in adulthood such as hip dysplasia and other orthopaedic conditions.
A good rule of thumb (Consider it the “Puppy Rule“🐶🐾) is a ratio of 5 minutes of exercise per month of age (up to twice a day) until the puppy is fully grown. For example, 15 minutes (up to twice a day) at 3 months old, 20 minutes when 4 months old, and so on until they are fully grown and can go out for much longer. After the age of 8 months, there is minimal longitudinal growth of bones going on, and by one year of age, most growth plates are fused or closed and no longer show on x-rays (source:Vet Surgery Central).
Physical activity for puppies should include- going for a walk or hike, training, Puppy Playtime, playing fetch, wrestling with other dogs, etc.
Another common cause of adolescent bone trauma or orthopaedic conditions is rapidly abnormal growth due to diet. Overfeeding your puppy can result in skeletal abnormalities, hip dysplasia (arthritis of the hips) and osteochondrosis (a condition that affects the joints of young, rapidly growing pups). A balanced diet is critical for good skeletal development and strong bones.
Puppies need plenty of hydration (you will notice that they drink a lot) and they require more protein, fat, vitamins and minerals than adult dogs. If you are cooking for your puppy, a homemade diet should contain proteins such as chicken, turkey, fish, lean beef. NO BONES or RAWHIDE!
Some Veterinarians may also recommend vitamins or supplements (glycosaminoglycans and chondroprotective agents) for high-risk breeds to help prevent damage to the growth plates.
While calcium supplements may sound like a good idea for developing strong bones, WARNING! Too much calcium can be JUST as dangerous as not getting enough. Consult with a vet and skilled nutritionist before giving any supplements or herbs and always ask about the nutritional needs of puppies when feeding a home-made or an all-meat diet.
Have fun with your new FURbaby; but remember, you wouldn’t make a 6 month old human baby run a marathon, so don’t make your puppy either!
Have a PAWSOME🐾🙏🐶 Day!
Dorothy Cline, Vet Tech Groomer Girl
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
Dorothy Cline 