Growth Plates

Growth Plates

Growth plates for dogs close on the average at:

Proximal epiphysis of the humerus 10 to 13 months
Distal epiphysis of the humerus 6 to 8 months
Proximal epiphysis of the radius 6 to 11 months
Distal epiphysis of the radius 8 to 12 months
Olecranon of the ulna 6 to 10 months
Distal epiphysis of the ulna 8 to 12 months
Proximal epiphysis of teh femur 7 to 11 months
Trochanter major of the femur 6 to 10 months
Trochanter minor 8 to 13 months
Distal epiphysis of the femur 8 to 11 months
Lateral condyle of the tibia 6 to 12 months
Distal epiphysis of the tibia 8 to 11 months
Proximal epiphysis of the fibula 8 to 12 months
Distal epiphysis of the fibula 7 to 12 months

Barbara Nibbling

As the owner of a slow maturing breed (berners), I do not assume that growth plate closure means that the dog is ready for full height agility. I also consider the tendons, ligaments, and other "parts" that might well need some additional time to develop. I wonder what others thing about this idea -- is growth plate closure really the green light?

I had no idea the problems that poor tunnel cinching could cause -- in fact, I had no idea that there are actually rules about this. I now check to see how tunnels are held down after my dogs were hurt during runs in which chains fastened to stakes were used to hold the tunnels. Because the chain was snug between ribs (as opposed to across ribs), the dogs went in
expecting the normal tunnel height and hit a solid chain a good two inches shorter than the opening. Unfortunately, I did not understand what happened to my first dog when she yelped going in the tunnel but when the second one hit the cinched chain hard, she backed out yelping and not able to walk well. I pointed the problem out to the judge and it was fixed, but I learned a hard lesson about the need to check how tunnels are held in place.

Tracking is a great dog sport to do with puppies, and being the youngest with a TD doesn't typically raise eyebrows ;) It seems easier on their puppy minds and bodies, teaches them how to "work" and builds a nice partnership. Given that I prefer to go slowly with both obedience and agility, I start my puppies in tracking at 8-9 weeks. My youngest berner got her TD on her six month birthday last spring -- the youngest age that a dog may enter an AKC tracking test. I have done early tracking with both her mother and half-sister and believe that it is an excellent foundation for future working events, including agility.
Mary-Ann Bowman

Repeated stress and / or injury to the growth plate of a bone can cause the ossification center to stop what it's doing which is forming the epiphyseal (or physeal) scar, which is normal and desirable.

Cartilage is clear on an x-ray and so when a dog is very young, there is a clear space at the both ends of the long bones. The first radiographic sign of bone formation is the appearance of a collar of mineralized bone around the shaft which is the epiphyseal.

Damage to this ossification process in its simplest, can bow the bone - at the extreme, the ossification center stops what it's doing, and between 4 and six months, you may have a radius and ulna which don't match. Elaine Mayher

Thanks for posting this. It is interesting to think about. However, a word of caution to those who might hang their hats on it. It is an average. There are many stories of much later closing plates. My small Kelpie bitch did not have closed growth plates in may areas at 14 months. I know of a teeny dog (those are the ones who are supposed to be at the quicker end of the growth plate closure average) whose plates were not closed at about 14 months as well.

The only way to know if growth plates are closed is by x-ray. I am not a fan of putting a dog under anesthesia any more than absolutely necessary. I have made the decision that it is important in this instance. These particular x-rays slowed me down in the jump training process of Kwiekje, thereby hopefully saving her body for a long and comfortable life. Doing x-rays early on (and we did them of legs, shoulders, back, basically everything) gives us a baseline for anything that might come up later in life. I hope we have no problems but if
we do, we know where we started and can see the extent of changes. Kathryn Horn

While damage to the growth plates will cause permanent damage to young dogs,
repetitive motion injuries can happen at any age. These can be intensified if
the dog's body structure is incorrect. This is one of the major reasons for
getting baseline xrays prior to beginning any intensive training for any dog
sport. If discovered early enough (through comparison xrays), repetitive
motion injuries can be corrected before permanent damage is done. Becky Harstad

You *cannot* go by "conventional wisdom" as to time of growth plate closure in various breeds and sizes of dogs. For some years now, my agility instructor has required proof of growth plate closure before allowing young dogs to jump in our classes. (They can take classes, but must go over bars on the ground until they mature.)

Quite a few dogs in our classes have NOT been "average" as to plate closure; we have had large-breed dogs (Labs etc.) whose plates have been fully closed at 12 months, and small-breed dogs whose plates have not closed until the dogs were well over that age. Our record-holder is a Sheltie whose plates did not fully close until *21* months.

Also, what many people fail to realize IME is that the growth plates are not closed when the dog stops growing, but rather fill in *after* growth is completed. According to a number of vets I've talked to, spaying/neutering can be part of the picture on this, since it changes the production of hormones which signal maturity; dogs who are "fixed" take longer for plates to close, with those who are done early taking the longest. As with everything else, there are
plenty of exceptions!

My own small JRT- 13 lbs full grown- stopped *growing* at 9 months; IOW she reached her current height and weight at that age. I had X-rays taken at 12 months (done with light sedation), and at that time the plates on her long bones were -to quote my vet- WIDE OPEN. When she was nearly 16 months old, she needed surgery on her foot, so I had them take X-rays again; at that point, she still had a hairline (literally- you practically needed a magnifying glass to see it) of open plate, which the vet said would close w/in a week or two. Sarah Fox

Additional discussion on growth plates will be added to this page, but the discussion regarding x-rays moves onto its own page X-Rays.