(UPDATE: diagnosis post #17) Intermittent, bilateral front-end lameness: differentials?

[RooTheDay]

(Long post, sorry. Have tried to make it as readable as possible while including most relevant prior art.)

BLUF: 11yo mare with neuro history currently presenting with varying degrees of intermittent, bilateral front end lameness (heretofore shortened as IBFEL) day over day, with the worse side switching randomly ride to ride. Sports med workup at NBC coming up soon; what to look at?

Background: Bought her two years ago (Nov 2022) as an eventer. She’s a US-bred unregistered ISH (mostly warmblood, not traditionally-bred) with a record through Modified. She was treated for Lyme in summer 2021 but successfully bopped around a couple unrec Trainings subsequent to that; at the time I purchased her she’d been back-burnered most of that year due to her owner focusing on her other horse.

Timeline:

• Nov 2022 - Mar 2023: sound, fantastic, an absolute delight, doing Training height SJ and going really well on the flat
• Apr 2023 - Sep 2023: pasture injury (stifle puncture wound with patellar ligament involvement; interestingly, showing the IBFEL even then as confirmed by VEI four days apart, but we thought it was compensatory at the time); pulled shoes and went to rehab
• Oct 2023 - Dec 2023: back from rehab and very footsore; put shoes back on and “footsore” turned back into IBFEL. Put hoof testers on her and did some low blocks up front and couldn’t find anything (I don’t have a ton of confidence in these blocks.) Blood tested for Lyme and EPM, results for both of which were equivocal; treated for two months and got her sound albeit unfit in Dec 2023.
• Jan 2024 - Apr 2024: coach (USDF silver medalist and Advanced-level eventer) slowly legged her back up for me while I recovered from a bunch of surgeries.
• May 2024 - June 2024: felt generally great under saddle but increasingly stupid spooky (usually very sensible) and tripping on manicured footing
• July 2024 - Sep 2024: pulled Lyme/EPM again (both equivocal again) and did a tail pull (bad enough to be unsafe to ride.) Treated Lyme/EPM for two months, with some improvement but not resolution, then went to NBC for a neuro workup, during which the IBFEL was once again observed.

Off-farm diagnostics to date:

• Nov 2022: PPE at B.W. Furlong (NJ); included flexions, neck/back/limb X-rays, and neuro exam. Flexions were universally negative and all the X-rays were good except the navicular ones bilaterally (satisfactory rather than good) and mild remodeling at C3/4 and C4/5. He wasn’t concerned about either at all and told me it was very rare to see a horse vet so clean.
• Jun 2023: lameness workup at VEI (VA); went on a Fri and then a Mon, first for initial eval and then for bone scan/ultrasound. IBFEL was apparent on Fri but not Mon; we blocked low on Fri and it resolved. X-rays of the area were unremarkable. Bone scan, in addition to the stifle injury/ligament, showed increased uptake in SI and bilaterally up front; at the time we chalked it up to compensatory patterns from the stifle injury.
• Sep 2024: neuro workup at NBC (PA): neuro exam (1/5 up front and 1.5-2/5 in back), neck radiographs (unremarkable), CSF tap for Lyme/EPM (EPM: negative, Lyme: equivocal per lab range but clinician interpreted it as negative), Vit E (normal). Given how good the neck rads looked, clinician didn’t think a CT or myelogram was indicated but suggested a) working up the IBFEL (that could be throwing off the neuro exam results) and b) potentially biopsying for PSSM/MFM if I wanted to spend more money vs. settling on a presumptive EDM diagnosis.
• (planned, upcoming) Oct 2024: sports med workup at NBC for IBFEL, because I do want to spend more money vs. a presumptive EDM diagnosis (and also, my luck is not great, but I also don’t think it’s “two EDM mares in a row” bad)

Major treatments to date:

• Jun 2023: Shockwave 3x for stifle injury (was sound for stifle injury after that + rehab)
• Nov/Dec 2023: Two months of minocycline and compounded ponazuril for presumptive Lyme/EPM (was sound after)
• Jul/Aug 2024: Two months of minocycline and compounded ponazuril for presumptive Lyme/EPM (fair bit of improvement in neuro sx, but not resolved, and IBFEL also continuing)
• Sep 2024: neck injections with HA 2x and a couple weeks of 2x/day Banamine (no real improvement for either)
• Oct 2024: 14 days IV oxytetracycline to r/o chronic Lyme (did see substantial improvement to neuro sx/tail pull, but IBFEL continues)

Things I’m already planning to investigate:

• ACTH testing in consideration of potential laminitis (I consider her EPICALLY ENORMOUS at the moment due to being out of work, but coach/vet assures me that she is fat, but not THAT fat; she gets 12 hours/day turnout, as much hay as she’ll reliably clean up while stalled, and 1 lb/day of a low-NSC RB, TC30)
• Blocks, U/S, and/or MRI to assess for potential navicular
• Balance films to check for NPA
• Maybe something soft-tissue in the neck?

What else would you want to look at? NBC is very good at what they do and so I will obviously be letting them guide me, but I find it helpful to have some idea of the possibility space before walking in.

[Horsecrazy3]

A local dressage BNT had a 10 yr old gelding who had IBFEL and was mildly neurological. After going down many rabbit holes to find the cause, the vets, owner and insurance company decided the best outcome for him was to euthanize and do an autopsy. He had EDM. A few more dressage horses in my area have been found to have EDM after being autopsy. Sadly, this horrible disease is being found more often in our horses. You have used many diagnostic tools and treatments to try to find the cause. I guess it comes down to how much more are you willing to spend to find the answer if you believe it is not EDM.

[IPEsq]

The lameness could be neurological. Or not. If you don’t see a reason to do myelogram as a first step, MRI of the feet is entirely reasonable. Also from my experience, mild neuro issues can cause real damage/lameness in the feet due to not quite right loading of the limbs over time. I had very shocking MRIs of my horse with neck issues…shocking given the low degree of intermittent lameness….everything around the navicular complex looked pretty bad.

It would be good for NBC to do their neuro workup also. With things like changing head position for different tests, that could tell you if they suspect some dynamic compression where you might want to go with the myelogram even though the radiographs look relatively ok. Has there been any change since he was last evaluated? There was a horse at my barn where they suspected EDM due to behavioral changes and clean X-rays. But he did have an abnormal myelogram—not EDM after all.

[Posting_Trot]

Based on a particular horse I owned (TB mare, not off the track) who had Lyme disease, the disease can be hard to eradicate, and it can also cause more or less permanent issues even once the horse no longer can be diagnosed as having an active infection.

Like you, I tried to chase down other culprits for persistent on-again, off-again lameness and soreness long after the first and subsequent treatments for Lyme. I know this recounting of my experience might not be very helpful, but it might be that the horse will continue to have persistent issues.

With my horse, I continued riding her strictly as a pleasure horse on trails, mostly pretty low key. And she was good with that–she was a horse that liked to have a job.

She ultimately colicked at age 23. It worsened very quickly and I had to have her euthanized. (She was originally diagnosed with Lyme disease at age 10).

Good luck.

[FjordBCRF]

Ive been eyeball deep in EPM land this year with my guy. There are a lot of people that don’t have great success with ponazuril (aka Marquis) and it’s not a one and done treatment for most. There are relapses. I’d look into the other EPM meds and potentially give something else a try on that end?

I’ve also been told not to chase titers when it comes to both EPM and Lyme as some horses with low titers will be tripping all over the place and a horse with a high titer may never show a symptom.

I wish you the best of luck, and feel your pain.

[RooTheDay]

@Horsecrazy3

I guess it comes down to how much more are you willing to spend to find the answer if you believe it is not EDM.

My guideline for euth on my previous EDM mare was when she was no longer happy and/or safe to handle on the ground. If this one also has EDM, she’ll get the same deal, but in the meantime I can’t afford a second one. So willing to spend a bit more chasing the lameness.

Was the dressage BNT Lauren Spreiser? (I don’t know her personally but she wrote about it happening to her, so wondering if there’s more than one out there.) I appreciate the response.

@IPEsq

If you don’t see a reason to do myelogram as a first step, […] It would be good for NBC to do their neuro workup also.

Thank you for the reply! Just to be clear (I know it’s a very long OP): I did already do a neuro workup at NBC in Sep 2024. I would have been willing to do a myelogram, but based on the findings the clinician didn’t think that would be helpful and suggested chasing the IBFEL instead, which is why we’re going back for the sports med workup.

@Posting_Trot

Based on a particular horse I owned (TB mare, not off the track) who had Lyme disease, the disease can be hard to eradicate, and it can also cause more or less permanent issues even once the horse no longer can be diagnosed as having an active infection.

Like you, I tried to chase down other culprits for persistent on-again, off-again lameness and soreness long after the first and subsequent treatments for Lyme. I know this recounting of my experience might not be very helpful, but it might be that the horse will continue to have persistent issues.

This is actually very, very helpful. Thank you for posting. I’d much rather have ongoing deficits/NQRness under saddle from chronic Lyme than EDM, because I’d rather have a pasture pet than needing to euth.

Did you ever do IV oxytet with your mare?

@FjordBCRF

Ive been eyeball deep in EPM land this year with my guy. There are a lot of people that don’t have great success with ponazuril (aka Marquis) and it’s not a one and done treatment for most. There are relapses. I’d look into the other EPM meds and potentially give something else a try on that end?

Thank you for posting! I’ve been reading your thread as well but haven’t had anything to contribute, and wish you the best of luck with your (very cute) boy as well.

Because the CSF tap was negative for EPM, I hadn’t planned to try empirically treating with something else. I wanted to do the gold standard IV oxytet for Lyme because there are case reports of horses with chronic Lyme where it doesn’t show in the CSF and the mare had a known Lyme history. Definitely something to consider, though.

Totally agree on not chasing titers in general–only pulled it originally due to the spookiness/tripping, which is very unlike her.

[Posting_Trot]

No, I never treated with Oxytet. When she was originally diagnosed, oxytet wasn’t a treatment that was available (at least with my local vets). In subsequent episodes (she was treated four times total for Lyme), using Oxytet wasn’t an option for other reasons. And my horse always did seem to respond to doxy and tolerated doxy well.

[Horsecrazy3]

It was a Canadian rider.

[RooTheDay]

@Horsecrazy3

It was a Canadian rider.

Ooof. Don’t love that data point, but it’s helpful. Thank you.

[cayuse]

My first thought was lami, I’d go ahead and and do the ACTH and IR levels too. Might as well rule that out if you can.

[IPEsq]

Oh sorry I missed that the previous neuro exam was that recent.

I think MRI is the way to go. But if there is nothing there that would explain things, then maybe time to reconsider going further with neuro. MRI is certainly a reasonable next step given bone scan results and what sounds like at least some response to blocks.

The other symptoms and recent diagnosis of some neuro deficits also fits—spooking and such would be common even with mild deficits (BTDT). Have you done an ultrasound of the neck? Or the pelvic / SI / lumbar regions? Checking the hind end to confirm that hind end neuro deficits don’t have a hind end component is fairly easy to do. Ultrasound of the neck might show if the joints look angry and could provide some other detail not seen on Xray. Has anyone ever mentioned ECVM or done the oblique X-rays for that? Though changes farther up C3 to 5 could also affect front end movement.

[RooTheDay]

Went to NBC last week and did a lameness eval. That day she was worse on the LF instead of the RF, so we focused on that; she blocked sound(er) at the LF coffin joint, so we did rads and an ultrasound.

Rads were very clean and ultrasound had some slightly suspicious areas but nothing definitive, so we’re now doing a MRI bilaterally up front. The working theory is either coffin bone bruising or some form of tendon/ligament tear, possibly on one side with compensatory lameness or possibly bilateral.

We discussed laying her down vs. taking her elsewhere for a standing MRI. Of course, laying them down is always a risk, especially with a known neuro horse, but I ultimately decided to lay her down for a few reasons:

• image quality is still better laying them down
• it’s possible to move up the leg if they don’t find anything when they’re laying down, whereas it’s a lot harder to do that in a standing
• all else being equal, I’d rather stay at NBC in terms of continuity of care

What we’ve already done did answer some questions:

• balance was perfect, so it’s not NPA (I wasn’t surprised by this, because I thought my farrier was pretty great, but I wouldn’t have minded the easy answer)
• also no sign of laminitic changes; discussed metabolic testing with the vet and she was willing to do it, but thought it was pretty unlikely, as did I, given history and age and presentation and usual response to work. We’re going to revisit after the MRI.
• navicular bone still looked great
• since she blocked sound(er), it seems unlikely to be originating from the neck, though it could certainly be multifactorial

@IPEsq

Have you done an ultrasound of the neck? Or the pelvic / SI / lumbar regions?

Good questions (and no worries on missing the date of the neuro exam, I know it was a really long post–thanks again for engaging.) My local vet ultrasounded the neck a few times. He thought she had increased intervertebral spacing but nothing definitive or obvious. I was unconvinced, and after discussing it with the vet at NBC, they also think that’s pretty unlikely given the response to blocks, so we’re holding off on further exploring the neck right now. We haven’t done anything recently with the hind end.

[GoodTimes]

Intermittent significant front end lameness during/after exercise - Update post 50

Here is a copy of the report and one of the MRI images for anyone interested. Findings: Left front: Foot/pastern: Normal flexor tendons and regional ligaments of the digit. Distal P3 has mild to moderate fluid signal throughout. There is mild diffuse fluid signal throughout the navicular bone. Fetlock: The fetlock joint has mild periarticular osteophytes. The medial aspect of the 3rd metacarpal condyle is diffusely mild to moderately sclerotic; worse along the dorsal medial aspect. There…

Hey OP, not sure if you’ve taken a look at my thread from earlier this year. Intermittent bilateral front end lameness. MRI showed some coffin bone bruising (see post 60 for the report). We did four-ish months of stall rest with handwalking, another month of small turnout, slowly started her back undersaddle around that time. MRI was about 7 months ago and knock on wood she’s sound, she’s turned out about 14hrs/day with her friends, and we’re doing short w-t-c rides 3-4 days per week, haven’t started jumping yet.
We initially put her in shoes with pads and pour ins for the last few weeks of stall rest and small turnout, but I don’t think she loved the pressure on her feet. So we reset her with just shoes and pads and she seems happier.

We didn’t do osphos as we haven’t decided if we’ll breed her at some point in the next few years. We had planned to do ProStride but an incompetent tech/vet team (not our regular vet) managed to turn my needle nervous mare into a needle phobic (going to get someone killed) in one visit. Took me several months to get her back to a point where we could do her dentistry. If she comes up lame again we won’t be able to block, it will be too dangerous. I plan to give her oral dorm before her spring vaccinations.

[ATXmom]

I’ve been thinking about your mare! Glad to hear she’s doing well (except for the needle phobia!). Have you done any new imaging since you’ve brought her back into work?

[GoodTimes]

@ATXmom

I’ve been thinking about your mare! Glad to hear she’s doing well (except for the needle phobia!). Have you done any new imaging since you’ve brought her back into work?

No we haven’t. Insurance wasn’t going to cover a follow up MRI and her x-rays beforehand were normal.

[ATXmom]

Got it! I didn’t remember that her radiographs were negative. Continued good thoughts for her recovery and return to work!

[RooTheDay]

MRI is done and mare is alive and home. She didn’t get up easily and she didn’t do a great job of walking back to her stall, but MRI is done and mare is alive and home.

Lateral collateral ligament injury on the LF plus a lot of suspiciousness in the sesamoid ligaments bilaterally. Four months of stall rest minimum.

I suspect, and vet agrees with me, that the injury pattern is likely due to her being neuro. So while the injury itself has a better prognosis than most other soft tissue type things, I’m very confident she’ll just immediately reinjure it in work unless she really did have undetectable chronic Lyme and the Hail Mary IV oxytet worked on it. Of course, we won’t be able to tell about that until she’s sound.

So I’m gonna do the stall rest and hand walking anyway, because why not? I can’t retire her in a big group situation, and I don’t have a farm yet, so I’m paying money for the stall anyway. Might as well use it. This decision is made much easier by the fact that she tolerates stall rest exceedingly well as long as the snack cart keeps coming around.

I’ve posted elsewhere on the forum, in September, that I was done with the roller coaster, done scrabbling, done trying to get somewhere; a big part of that was taking a step back, looking at the pattern, and believing that even if she got over whatever the current This was, there would ultimately always be another This at intervals too regular to make any progress. I would have been happy to be wrong, but I’m not entirely without smug about being right, and this would have sucked a lot worse if I hadn’t already grieved the dreams.

So I’m grateful for that.

I will be even more grateful if her neuro issue is ultimately not EDM. Because, in the end, I followed Wofford’s advice and bought one whose face (and big, lovely ears) I really enjoy.

[IPEsq]

@RooTheDay

MRI is done and mare is alive and home. She didn’t get up easily and she didn’t do a great job of walking back to her stall, but MRI is done and mare is alive and home.

Lateral collateral ligament injury on the LF plus a lot of suspiciousness in the sesamoid ligaments bilaterally. Four months of stall rest minimum.

I suspect, and vet agrees with me, that the injury pattern is likely due to her being neuro. So while the injury itself has a better prognosis than most other soft tissue type things, I’m very confident she’ll just immediately reinjure it in work unless she really did have undetectable chronic Lyme and the Hail Mary IV oxytet worked on it. Of course, we won’t be able to tell about that until she’s sound.

So I’m gonna do the stall rest and hand walking anyway, because why not? I can’t retire her in a big group situation, and I don’t have a farm yet, so I’m paying money for the stall anyway. Might as well use it. This decision is made much easier by the fact that she tolerates stall rest exceedingly well as long as the snack cart keeps coming around.

I’ve posted elsewhere on the forum, in September, that I was done with the roller coaster, done scrabbling, done trying to get somewhere; a big part of that was taking a step back, looking at the pattern, and believing that even if she got over whatever the current This was, there would ultimately always be another This at intervals too regular to make any progress. I would have been happy to be wrong, but I’m not entirely without smug about being right, and this would have sucked a lot worse if I hadn’t already grieved the dreams.

So I’m grateful for that.

I will be even more grateful if her neuro issue is ultimately not EDM. Because, in the end, I followed Wofford’s advice and bought one whose face (and big, lovely ears) I really enjoy.

I’m so sorry the news is not good. But I think this should be a pinned post. So many of us with NQR horses on this BB, and I think we could use a bit of this kind of perspective now and then. It’s so hard. We want to help them. We want to fix them. Partially for our dreams for us, but also our dreams for them. And sometimes it is the best thing for both to accept the heartbreak.