Pin firing is a very outdated practice that used to be used more commonly to treat all manner of tendon and ligament injuries, particularly in racehorses. It really has very little therepeautic value (if any) and is a fairly barbaric practice.
It consists of injecting acidic or otherwise caustic agents into the tissue with the idea being that an acute inflammatory response will be initiated, thereby helping to 'heal' the injury by recruiting blood cells/leukocytes to the site of injury. It's a load of horse poop in my books but the sad fact is that many horses were subjected to this type of treatment (including my own mare). The 'recovery' that some horses made as a result of being pin fired was most likely due to the several months holiday they had to recover from the pin firing itself. I.e. They would have recovered just as well being spelled and not
There *shouldn't* be ongoing inflammation as a result of pin firing, and if there is (as in your case), it may be difficult to decipher if the inflammation is a result of the pin firing, or the original injury. Only a vet will be able to tell you that.
I can tell you that my mare hasn't taken a bad step and has remained sound under a light to medium workload. I probably wouldn't choose to stress her greatly with a heavy workload or a lot of jumping. Many people won't touch a horse that has been pin fired, and with good reason as there is the potential for long term side effects. Not in every case but it is certainly a risk that you run in such a horse.
In regards to this:
Originally Posted by TrailxxRider
He tosses his head and bucks around when you go to feed him in the morning too. I've never heard of a lame horse doing that
I have seen this all too often. I have seen horses that have severed tendons, ligaments and had horrific laceration type injuries behave in this exact manner. Don't be fooled by displays of high energy and moments where no lameness is evident, sadly a horse can, and will, ignore the pain response if they get excited or fearful.