I've been thinking alot about the recent Derby tragedies (so sad...)  and I would like to relate this to training your dog for agility purposes for those of you who might be considering it.

One thing I learned early on with Bailey is that  puppies should not jump anything very high until their growth plates close.   Safe, regulation agility equipment is expensive and you need to know how to use it.  Start with a puppy agility class with a local trainer. You'll learn foundation work that you will need as you progress and work on "puppy" sized equipment. There is alot more to agility than just jumping.  A very imprecise guideline for growth plate closure in dogs would be 9 - 12 months for dogs under 50 pounds and 10-14 months for dogs over 50 pounds.  The negative impact of jumping and flexing on immature, growing bones can be devastating.

I started Bailey in agility at the age of 10 months... and worked with "baby" equipment until he turned a year old.  When he turned 1 year of age, I had him x-rayed prior to jumping him at his AKC required jump height (12-inches).   I know... 12 inches doesn't seem very high for a type A rat terrier does it?  It isn't really.... Bailey can jump three times that high, (as evidenced by the missing bunch of bananas from the kitchen counter one day when I returned home after being gone for only an hour).   But to continually jump a dog at a higher height than he is structurally built for is stupid and dangerous to the dog's health. 

So I took the time and incurred the expense of making sure he was old enough and structurally  'sound' enough to do what I wanted to do with him.

Just wish the people in the horse-racing industry would do the same....

And not just the racing industry Nora - other parts of the horse world.  When I trained in Germany we didn't back a young horse until well into their 3rd year.  And NO horse should ever be jumped before 5 years old.  Quote from Reiner Klimke, noted dressage trainer: As Klimke says, "One must have the patience to wait until the horse is physically and mentally ready for the work demanded of it."

BTW I'm now seeing comments in horse forums that Three Belles' ankles were not "closed'.

http://www.suite101.com/article.cfm/young_horses/69350/1

"Thoroughbred racehorses are asked to carry a jockey at high speed, for long distances, in one of the most strenuous equine sports there is, at the age of two. Yet Lipizzaner stallions in Vienna, who carry out leaps and pirouettes requiring the greatest of suppleness and concentration, are left in their fields until they reach the age of five. Which is right?

The debate over what age to start riding a young horse is a fierce one in the horsey world, and it raises tempers faster than you can say "physically mature". Which is what the whole debate hinges on - for opinions differ widely as to when a horse is sufficiently developed enough to take the weight of a human being.

As your horse grows, his bones and joints get stronger through the fusion of his growth plates - flexible areas which, at birth, are separated by a layer of crushable cartilage and allow the horse's bones to lengthen and grow. There's a widely-held belief that these growth plates only exist in a horse's knee: but in fact, there are growth plates almost everywhere that a horse has joints. They are all weak points, and unable to bear much weight, until they fuse - that is, the cartilage disappears and they join together in one strong unit. "