I have always noticed that my colt...4yr old... always stumbles in the hindend. I noticed it last year when I started riding him. I notice it mainly on firm ground out trail riding or walking across the pasture. In worked up dirt I don't notice it at a trot or lope. I also notice he stands with his back legs crossed.. just thought I would throw that in there in...might mean nothing.  Is this stifle related? I have a vet apt for next Thurs. 

EPM.

Could be several things but EPM tops the list

My gelding stumbles on the left hind when stopping or slowing down a gait etc. Has done it for years. This spring we decided to prolotherapy the stifles and he no longer has the issue. 

stifles, hocks, epm.

Sounds like EPM. One of the test a vet does is cross the horses legs. They are supposed to un cross them fairly quickly. If they do not I’m cross them that is a big sign of EPM. 

I assume they are crossing the back legs? Mine stands with his back legs crossed all the time.

Other than stumbling now and then on a ride... he doesn't stumble at a trot or lope or when I am working him. he really uses his hindend.  I don't think we have EPM in our area?

Your horse is probably not stumbling, his stifle is catching . Very common in young horses, especially geldings. You’ll feel it mostly on downward transitions (like going from anlooe to a trot) or going down hill.Sometimes lack of fitness will cause it. Open growth plates on the tibial crest can cause it, hormone imbalance, sore Hocks/stifles or EPM can cause it.

They cross both front and back from each side, one at a time. Where abouts are you from

Bumping this up... would like to talk to anyone who is knowledgeable on EPM... you can send me a PM 

I would be getting my horse seen sooner than next week. This isn't good 

https://m.facebook.com/story.php?story_fbid=1610387679095199&id=263253420769845

the  link should take you to a very informative video on EPM  by Dr Crosby. 

I had a horse that did this. He was 16. Had him tested for EPM....negative. He had cervical vertebral malformation of the C4- C5 of the spine. 3 vets confirmed and said he was born with it and they usually start showing signs at 3 to 4 years old. One vet worked on the track for many years. You might look into it. They also told me this mimicks signs of EPM.

With his age I would try to rule out wobblers for sure before jumping to EPM.  Definitely worth checking in with your vet.  

He *could* also be going through a normal I-don't-know-where-my-feet-are colt growth spurt (which is nothing) in addition to the suggestions above.

Me too. Who has the info on the research/product from Florida?

Parhogenes.com

Decoquinate and levamisole. 

IMO not strong enough or long enough treatment.