Mystery Lameness - Help Please

[CollegeEventer1]

Hi everyone. Hoping to see if anyone has ideas for my mare as I’m at my wits end.

My mare is a 7 year old OTTB. She raced once and then retired at 3 as she was so slow. I’ve had her since then and we’ve evented novice/training level. Other than previous shoeing issues and TB feet, she hadn’t had major soundness issues until now and was consistently in work for last few years.

This winter she was coming back from a popped splint. She did this during her winter holiday in the field and I was very conservative with her return to work. She was not lame from the splint. After her stall rest, she was playing on the lunge and actually tied up for the first time. It was chalked up as a fluke because of the combo of stall rest, cold weather and it being her first winter up north.

Side note: When we lived in Florida, she had mild anhydrosis during summer but I was able to manage it after discovering this during the first summer I had her (her sweating did shut down for a weeks that first summer).

I slowly continued to build up her fitness. In early March, she felt weak on her left hind but was not visibly lame. We focused on strengthening work as she has previously been diagnosed with weak stifles and had been out of work. This included saddle fit check, chiro, adequan, etc.

She came in definitely lame on the left hind a few weeks later in March. The vet evaluated her and flexions were inconclusive as she flexed positive on the RH instead. Xrayed both hind legs and we injected her stifles as she had some mild arthritic changes. The injections made a mild improvement for couple weeks but then she was significantly worse after 3 weeks from initial injections. Proceeded to do nerve blocks, which were also inconclusive. Blocking the stifle made her worse and blocking the high 4 showed about 30-40% improvement so we ultra-sounded the LH stifle and suspensory. Nothing abnormal.

In May, she was referred to the state hospital for a bone scan, suspecting it was something higher up. Sports vet was not concerned with her X-rays. The bone scan showed some uptick in the LF fetlock and the LH hock and fetlock. Nerve blocks were redone but also inconclusive. Vet ultrasounded the stifle again and also the pelvis due to her LH muscle atrophy. Nothing abnormal again.

Referred to the internal medicine for a neuro exam. Showed mild deficits isolated to her neck and proceeded with EPM spinal tap and neck X-rays. EPM test was negative and neck X-rays showed mild arthritis of C6/C7. Vets have now recommended to take her to Rood and Riddle for their opinion and for a CT myleogram for possible nerve compression (CVCM). Her LH will occasionally buckle while hand grazing. Lymes test was also negative.

I don’t doubt my vet’s suggested next step but obviously CVCM would be a devastating diagnosis. I’m wondering if anyone has any anecdotes they can share or advice. Some days are worse than others but she has a noticeable hitch even on good days. I’m thinking of testing her for a muscle disorder too but that may be another shot in the dark. Thank you so much for reading my novel.

[StormyDay]

Wow it really sounds like you’ve covered a lot of your bases so far. I have no advice but hopefully some others on here can help.

[Apocalyptic_Pony]

Have you tested for muscle myopathies? Pulled vitamin E levels? There isn’t a test for pssm2 but there’s a genetic test. But there are others they can test via muscle biopsy and blood test. I’m starting to think these are under diagnosed in TBs. For these mystery lameness horses I think it should be on the list. (signed, someone who is on my second mystery lameness OTTB)

[JB]

@Apocalyptic_Pony

There isn’t a test for pssm2 but there’s a genetic test.

The hair/genetic test for any PSSM2/MIM is sketchy at best. Yes, it can find variants but finding those does not mean the horse has the disease. Dr Valberg and some others have tried to validate Equiseq’s testing and can’t do it, and of course Equiseq won’t publish anything, even when promising to years ago.

That said, if a horse is clearly symptomatic, and since it seems some of the variants respond a bit differently to management, it may be worth seeing which, if any, variants are found, and attempting a management change based on that.

Now, THAT said, this doesn’t read like PSSM or any type. Never say never of course, it just doesn’t sound like this sort of issue.

@CollegeEventer1 has any diagnostic work been done into the pelvis? Did the bone scan cover that area?

[CollegeEventer1]

Thanks everyone! I have not tested her for muscle myopathy yet as the vets thought it would be very unlikely for a TB mare. But they are open to the idea at this point. Lol. I did increase her vitamin e to 5000 a day this week and she looks improved…

@JB her bone scan was fully body and if I remember correctly, she had some uptick in the right side of her pelvis. Her ultrasound of the pelvis didn’t show anything though. She has had an asymmetrical RH Hunter’s bump.

Does it read like CVCM at this point? I’m just cautious that I will go through the CT and still not get an answer.

[Paint_Party]

I’m sorry you are having such a struggle helping your mare and it sounds like you’ve been on an extensive fishing expedition trying to find the cause. This comment stood out to me, though:

@CollegeEventer1

Thanks everyone! I have not tested her for muscle myopathy yet as the vets thought it would be very unlikely for a TB mare.

I’m not sure why the vets would think it would be very unlikely in a TB mare. It might be rare but it does occur (had one myself) and would not be that difficult to test for. Since it seems you’ve nearly exhausted every other cause, I’d push for this as at least a possible contributing factor to her unsoundness.

Other than that, I’d go ahead and explore the CVCM route, too. You might as well go all in at this point.

Again, I am so sorry and wish you good fortune soon.

[beowulf]

Can you humor us with a video of her going, W/T preferably, but even loose in a field is fine.

It sounds like you have exhausted a lot of time and vet bills getting to the bottom of this. I’m sorry you’re in this position.

Just reading along as you have shared my gut instinct would have been pelvis, but then you said that the pelvis was ultrasounded. Was anything diagnostically found (even if not of “note”) in that area in the bone scan?

In the meantime if you have not already, I would put her on a “shivers/PSSM” diet. High high Vit E (I do 7000 IU / day), low starch. I do Vit E + Alfalfa Pellets (soaked), RB. And 24/7 turnout. Not saying it is what is causing these issues, but it helps neurological horses. If you see a definitive improvement, it can help point diagnostically to a few different disorders.

[CollegeEventer1]

It has certainly been exhausting and expensive! This is the report on the ultrasounds: Ultrasonography of the stifle was within normal limits. Transrectal ultrasonography revealed no abnormalities of the lumbar discs (L4-5, L5-6, and the lumbosacral disc), the intertransverse joints, or the sacroiliac joints.

@beowulf what does RB stand for please? I will try to get some videos going both directions.

[beowulf]

Ration Balancer.

And if you have any photos or clips of before she was symptomatic, look back on them and see if you see where the first visual symptoms of atrophy appeared. You don’t need to post them, just might help you formulate a timeline.

Providing the videos is as much for you to get as many seasoned eyes on your mare and help get to the bottom of it, as it is educational for COTHers to see and know what to look for in their future, should they ever come across a case similar. If you have any photos from her track listing, focus on her hind end and ask yourself: is that asymmetry there, but subtle? It is not uncommon for the slow race horses to retire because of SI and stifle strain, or sometimes even pelvic wing fractures (which can have a good prognosis for sport after recovery).

I had a gelding with a significant pelvic break. Part of what you shared sounded familiar. But I would think it would have shown up diagnostically for you.

It could simply be c-spine arthritis, which does cause forelimb lameness and asymmetry. Next time they are looking at your mare, ask them if neck injections would help. It won’t if the true reason is CVCM, but if it is “just” cervical arthritis, injections usually help.

[JB]

@CollegeEventer1

I have not tested her for muscle myopathy yet as the vets thought it would be very unlikely for a TB mare.

I think “they” are realizing it’s probably more common than “they” thought, especially RER. But even that doesn’t sound like this.

@CollegeEventer1

her bone scan was fully body and if I remember correctly, she had some uptick in the right side of her pelvis. Her ultrasound of the pelvis didn’t show anything though. She has had an asymmetrical RH Hunter’s bump.

this speaks much more to her symptoms, and makes me wonder if the issue that caused the Hunter’s Bump has fractured something in her pelvis, not just torn the ligament

[anonevent]

Dumb question, but sometimes the most basic things get overlooked…have her vets taken her temperature? Done CBC/Chem recently? Current fecal test? Maybe look at a blood smear for bacteria?

I’m trying to think of inexpensive things that would be very annoying to only remember after you return from R+R.

[CanteringCarrot]

Have you had her tested for Lyme disease?

[Amberley]

Does she have muscle atrophy? The gradual onset does sound like nerve compression but there is typically some kind of asymmetry visible. If not I would suspect it’s related to the hunter bump in some way- scar tissue or nerve compression in that area or something they couldn’t find on the scans and us. Also as she’s a mare has anyone discussed ovaries? I am starting to think ovaries can cause any symptoms they feel like at this point.

btw, they have had good success doing surgery on nerve root compression in europe, and I think it’s being done in the US now. If you do inject and have good results at first (and have insurance) it’s an option.

[IPEsq]

Did she only tie up the one time? At first I was thinking RER, but maybe it’s not.

There can be issues with the pelvis that we cannot image. Other than the arthritis, did they take measurements of the neck that led them to suspect narrowing/compression?

I’ve been close with a couple of friends’ horses with CVCM, and that is absolutely not good. And can become symptomatic at a later age (one was only 5 but another 2 were 14, all different breeds with one being TB). The TB also had arthritis everywhere in the neck and ECVM as well, and so it seemed remarkable he did as much as he did in hindsight.

There are some treatments for nerve root compression that may have decent prognosis, but not for spinal cord unless it’s a basket/fixation surgery candidate.

[clanter]

@CanteringCarrot

Have you had her tested for Lyme disease?

buried in the original post

Lymes test was also negative.

[CollegeEventer1]

@Amberley she does have muscle atrophy over LH that has gotten worse since she’s not been in work.

@IPEsq her neck X-rays included those measurements and they were not indicative of CVCM but vets mentioned that does not definitely rule it out. She has only tied up once.

If it is a pelvis issue we cannot see, could SI injections help or just turn her out for awhile to see if that helps? I will see what the vets think about the neck injection where she showed arthritis.

[IPEsq]

I had a horse with chronic SI joint instability and lumbosacral pain. We did all the imaging and bone scan, and it all looked good. SI injections were tried because he was bucking a lot and then developed more of a bunny hop gait in the canter, and it helped him to a point, but even after years of doing that, the cartilage surfaces looked horrible on necropsy. He was never off behind or asymmetric, and no EPM, and his neuro exam was normal. I did always suspect a muscle thing with that horse as well, but even after the biopsy was available for MFM, at that time they didn’t have a management protocol, so I never did the biopsy.

[CanteringCarrot]

@clanter

@CanteringCarrot

Have you had her tested for Lyme disease?

buried in the original post

Lymes test was also negative.

Ah ok, thanks! I skimmed through and didn’t see it.

Maybe because I was looking for Lyme not Lymes… Sorry, it’s a petty pet peeve of mine.

[danacat]

I have nothing to add here, but I know how hard these ‘mystery’ issues can be. Wishing you the best of luck getting to the bottom of it.