We have no evidence that Bob injected the joint. He might not have. He might have injected it at 14 days and thought he was clear, or 21 or 30, or whatever, and had a horse with an odd metabolism that took longer than expected to clear it.
One thing I will point out is that it probably totally inaccurate to assume that just because you are “supposed” to rest a horse after a joint injection, it means you “have” to rest a horse after a joint injection. If you ask 10 vets what their post joint injection protocol is, you will get 11 answers. I have heard and seen anywhere in the spectrum from:
Wrap and stall for 24 hours, paddock x 48 hours, turnout x 48 hours, then slow intro to work over the next several days.
to…
Give 'em the rest of the day off, one low impact day, and then put 'em to work to get that joint moving - that tiny needle puncture is plugged with fibrin by now and you don’t want that spreading.
For the record? An injection of a steroid is pretty darn immediate. That’s why we give steroids. They dial inflammation back very quickly. That’s also why you’re average riding horse is getting HA (longterm lubrication) and many vets no longer use steroids in joints, as it is a fast but shortterm fix that increases the risk of infection. Doesn’t mean you don’t give both HA and steroids together - immediate relief + longterm lubrication - just means steroids alone for arthritis (which is why you and I are using joint injections but certainly not why most racehorses are using joint injections) are a poor choice in the eyes of most practitioners I talk to.
My own horse received steroids in his coffin joint long ago because the lameness guru narrowed the issue down to that area after doing everything up to and including an MRI. The steroid helped. Why did it help? Because he had a deep sole bruise, and getting a dispersal of steroid through the area dialed the inflammation down and made him comfortable enough to look almost immediately sound. It took three years of owning him before I got his tendency towards sole bruises under control. It took weeks at a time for every bruise, whereas that one time steroid injection immediately fixed the “problem” - or at least hid it. I wasn’t interested in the risks associated with injecting steroids (I also now knew it wasn’t a joint issue) so instead of experimenting with injections every time, I got to wait around and twiddle my thumbs while he healed. Of course, I wasn’t staring down the Derby, just missed clinic after missed clinic and missed show after missed show.
Yes, I wince at the idea of injecting young horses with steroids, not to mention all the other drugs they use. I met a lovely, lovely Standardbred gelding who died of renal failure at five years old. Rescued off the track, landed at the perfect home, got to enjoy it for a little, and then probably died because his trainer over used anti-inflammatories or Lasix or who knows what steroid or other performance enhancer and blew out his kidneys.
This is why we need racing to come down like a hammer on every teeny, tiny, piddling positive test. The horses get no say on what goes into their bodies.