She came straight from the breeder. They had all that taken care of for me and assure that she is ok to ride. Thanks for making me feel like I treated her poorly though. I would NEVER put her through something that I thought was not good for her. Anyone else have any suggestions?
Unfortunately, a lot of breeders are not 100% honest when selling ex race horses, or the owners aren't as knowledgeable as they claim to be. I have worked as a vet tech with only lameness in racehorses
(TB, QH, STBD). I have a pretty good idea that the 'blown knee' they are referring to is most likely a slab fracture and/or chipping to the 3rd carpal bone in the knee. Sometimes time will heal these kinds of injuries, but if she is going lame after only a light ride it is more than likely that the joint space is compromised by arthritis or actual bone fragments in the joint space/ joint capsule.
Regularly bone chips in the joint space don't bother horses in light riding once the initial damage has healed and the fracture has healed, but over time these chips can move/ shift and cause discomfort. Do you know if she has had surgery after her injury? If she has, and the veterinary surgeon is a good one, there will likely not be a lot of arthritis (again dependent on the severity of the initial injury).
We have had success with helping horses become more comfortable with Hyaluronic Acid and Depo injections into the joint space, as we as IM Adequan/ Legend can also help with inflammatory reactions and arthritis.
I would suggest getting some x-rays (they really aren't as expensive as most people think) from your vet and see what they say will help as all of this is dependent on what the knee actually looks like inside. There are plenty of therapies for injuries like this one and can help your horse be ridable and comfortable, it really just depends on how much you would like to spend.
Until you get a vet out though, I would suggest not riding. It may not be and and I realize that you would never intentionally put your horse in discomfort, but I think not riding until you know the issue with her knee would be the best for her.