Deep Flexor Tendon Injury?

Question
Hello, thanks for entertaining my question.  I have a 5 year old QH that I was training for barrels when he came up with an unusual lameness.  Every day would be a new day, one day just off a little, next day fine.  Somedays he would work out of his slight 'offness' then other days he wouldn't show lameness.  After attending an intensive clinic, he became pretty lame.  I could't get in to our vet for 2 weeks so I gave him that time off.  He became more lame in that time off than before.  We have about a 1/2 acre paddock that does slope some that they have daily turnout in.  At a walk you could really see his lameness, then he would canter and run around and there was no lameness.  My vet did a lameness exam on him, there is no heat, no swelling on his leg or hoof.  (Front right).  With the hoof testers there was a very slight response across the bars and heel, but not what you would expect for his lameness.  We blocked and isolated the lameness to the hoof.  X-rays were fairly clean, maybe just a slight irregularity to the the navicular bone.  The vet said that was not enough to cause the lameness.  So, w/out doing an MRI, (which we are debating on doing), the vet ruled it as most likely being the DFT.  I should go look at a picture to make sure I have that terminology right, the tendon that runs under the navicular and connects to the coffin bone.  Anyhow, this horse has other oddities as well.  He doesn't want to cross over to the right on a hind end pivot, he'll do a little rear/hop thing and his lameness was intermittent until he had a lot of time off.  He is now on stall rest for a month, then stall/run rest for 3-4 months.  He has a wedge pad on as well.  I have never dealt with this before and have another horse that was pre-navicular if you will, and although he walks pointing his toe into the ground some, he just isn't as lame as we would expect for navicular.  One other thing I will mention, his radiographs showed that the navicular was less dense to the inside.  Medial? side.  Again, the vet said it doesn't add up to the lameness he is showing.  So, all that information to say, what is your advice and do you think it falls in line with a DFT injury?  What else could be going on in his foot to cause this lameness?  Thanks again for any advice you can give!

Answer
Deep flexor tendon injury in that area is very uncommon. This can just be foot brusing or even an abscess brewing. DO NOT do an MRI at this time. He hasnt been lame long enough nor has he had enough work-up to warrant jumping to an MRI right away and at a significant expense. I would reblock him and also, on another day, block the coffin JOINT, not the nerve, on a separate day. If he continues to be lame and to block the same way, I would also consider evaluating the collateral ligaments of the coffin joint by ultrasound. This needs to be done by someone with alot of experience at looking at these. Also, the navicular bursa can also be blocked, but it is not easy to do and needs to be done by someone with alot of experience in blocking these. The block will anesthetize the navicular bone and the associated structures in that area including that area of the deep flexor tendon and the navicular ligaments. I wouldnt get overly aggressive yet though. Common things being common, many of the lamenesses I see like this work themselves out and are presumably associated with the hoof structures. IF the lameness persists or becomes worse and the other diagnostics Ive suggested are not helpful, thats when you might consider the MRI or even nuclear scintigraphy. It could be a DFT injury, but thats certainly not the first thing I think of and this may be something much more benign. good luck. let me know how things progress.