SI Diagnostic Blocks

[Pally]

So this question is purely out of curiosity. I don’t have a horse with suspected SI disease (heck, I don’t even have a horse at the moment) but always looking to learn more.

I was watching a talk by Dr. Sue Dyson about canter dysfunction. She emphasised a big part of how she knew it was dysfunctional in many examples was because of the positive changes that ensued after diagnostic analgesia of (aka blocking) the SI. I honestly didn’t know you could block the SI. I don’t have a lot of personal experience with working a horse up for suspected SI trouble, but my understanding was that it was largely based on process of elimination (maybe some imaging, but there are obviously limitations) and then perhaps injecting to treat, and see if there is improvement.

Just curious if anyone has had their horse undergo a diagnostic block of the SI joint? (And feel free to describe the process and results too!)

[SolarFlare]

When my horse was undergoing diagnostics, I was also told the SI wasn’t blocked. I think it’s because the horse would need to be sedated for the injection, which is done with giant needles and is ultrasound-guided. They need to be standing still. How would you evaluate the effect of the block on a sedated horse? I can’t imagine lunging or jogging a horse that’s dopey.

I’m curious to hear as well if others have had this done and what the process is.

[starsandsun]

My vet and I discussed this, and I would not be comfortable (nor would she) blocking so close to the spine. Instead, we’re using the no doubt slower route of ultrasound diagnostics and then treatment and looking for improvements.

[Gardenhorse]

Interesting, I wonder if anyone but Sue Dyson is doing it. From my reading, most vets think it is a bit risky. My horse had a transrectal ultrasound and her SI injected on Friday, and the vet never even suggested blocking.

[No1]

The horse is walked for 15 min after injection and then reassessed ridden. If local anaesthetic solution is placed too far caudally there is the potential to induce hindlimb ataxia or sciatic nerve paralysis. The nerve block technique is not specific and it is not possible to differentiate between pain due to SI joint disease, lumbosacral and ventral sacroiliac desmitis.

Quote from here: https://www.myeventflo.com/event-lecture.asp?lectID=318

This is why most practitioners will not block an SI. The risks far out way the potential benefit. It’s just as easy to inject and not run the risk of having a 1000lb plus animal completely unaware of it’s hind end.

[Pally]

@No1@all

The horse is walked for 15 min after injection and then reassessed ridden. If local anaesthetic solution is placed too far caudally there is the potential to induce hindlimb ataxia or sciatic nerve paralysis. The nerve block technique is not specific and it is not possible to differentiate between pain due to SI joint disease, lumbosacral and ventral sacroiliac desmitis.

Quote from here: https://www.myeventflo.com/event-lecture.asp?lectID=318

This is why most practitioners will not block an SI. The risks far out way the potential benefit. It’s just as easy to inject and not run the risk of having a 1000lb plus animal completely unaware of it’s hind end.

Thanks. I hadn’t seen that particular piece yet. I’ve had a chance to do a little reading of some scientific papers and definitely gathered there was some risk to the procedure, and certainly isn’t simple. Then came over to the here for the “real world” side of things, to see if anyone is going ahead and doing this. As Gardenhorse said, it may just be Sue Dyson (and perhaps others in a research setting) performing these.

@SolarFlare I will have to rewatch the recording of her presentation (like 3 or 4 times, lol…there was a lot of info in it!) and check if the “after” videos she showed were post-block or post-treatment. I want to say it was a mix of the two, but honestly was so focused on the watching the movement and whatnot, I am not sure. I have definitely seen horses receive some sedation for the standard blocks to the distal limbs, and jogging/lunging is a non-issue. Can’t specifically recall if the horses ridden after blocks (as would be necessary for most of these tricky canter dysfunction cases) were sedated, but I trust that the vets that do this a lot have their “chemistry” down pat (ie, they know exactly what sedatin cocktail to use for the right potency and duration of sedation).