Bilateral hind end soreness, X-rays clean

Hi COTH. I have amazing luck.

My mare just turned 5 and I’ve had her for 7 months. 16.1 hh OTTB, track trained but un-raced (“too slow”). Got her green and going fine W/T/C, chill on the trails or really wherever. Passed her PPE, liked her personality so all systems go. She has been in light work off and on over the winter and fall (maybe 2-3 rides a week, sometimes in hand stuff like long lining, hand walking on the trails). I had surgery and some other factors came into play so work has not been consistent, but this wasn’t any different from her previous home. Was turned out 8-10 hours a day, then moved to 24/7 turnout month and a half ago. No diet changes (24/7 alfalfa/grass mix, handful of triple crown senior for vitamin E, cosequin when I first noticed her NQR, magnesium when she first started “acting up”).

S l o w l y progressive behavior oddities, and very inconsistent too. Never sure what horse we get day to day.
Small stuff like fidgetyness at the mounting block where before she stood like a statue, anxiety in new places despite being unfazed by new places before, not wanting to stand still under saddle but not wanting to go forward. Off and on…some days, she’s the horse I bought, stands like an angel in cross ties, quiet under saddle…other days, totally on edge and hard to settle. Doesn’t coincide with heats that I have tracked. Never has bucked/reared under saddle but prone to being challenging on the lunge…nothing extreme either, small rears and ear pinning but would eventually proceed. Reluctant to canter. Bunny hops in canter (not noted in cantering under saddle vids at previous home months prior). Better behaviors lunging with tack on and side reins but not always. Classic signs of discomfort, but this came on so slowly aside from the very first time anyone asked her to lunge (I was not there, apparently she made a big fuss about it). I had pinned it on her being a youngster.

Sometimes explosive in hand but no real rhyme nor reason to it. Will be leading along quietly or standing and then just start bucking/rearing/cavorting, never seems to matter where she is being led. At first I thought it was baby horse sillies but now, not so sure.

Has always been sticky picking up her hinds…despite working with her on this, she has been slowly getting worse about wanting to hold a hind foot up. When I first bought her, she’d pick it up reluctantly and it seemed like she simply wasn’t used to being asked. But in the last month or so it seems very uncomfortable for her to hold a hind foot up. This is bilateral.

Off and on NQR at the trot, hard to pinpoint a location. Not head-bobbing lame but odd looking. Would disappear for weeks at a time and thought perhaps she was laying on a leg too much.

Never swollen or hot anywhere. No signs of old injuries. Has had the chiro out twice who commented on her SI joints but it was nothing extreme.

Out of ideas, she’s been on paddock rest for the last two weeks finally waiting for a vet visit. Today they took X-rays of both fetlocks, both hind feet, both hocks, both stifles. No signs of arthritis, injury, bone chips etc. No swelling. No visible fluid on X-ray (which it isn’t always visible, true). She was the worst I’ve ever seen her be about lifting her hinds and tolerating her stifles being handled…kicking out with gusto. Needed double the sedation and twitching. I’ve never seen her do this, but it’s been a few weeks since I’ve personally asked her to lift her hinds.

According to vet, on a 1-5 scale, she presents as 4/5 sore trotting on the lunge both directions equal. About a 2/5 trotting away straight. Nothing too noticeable walking.

We need to haul her into the clinic for more diagnostics. Nerve block wasn’t recommended since she needs to be sedated currently for any manipulation of either leg. Have I mentioned that none of this behavior was present at her PPE?

Otherwise she is a sweet horse who walks up to you to be caught. Not super into being groomed but not cinchy, I treated her for ulcers the first month I had her home as she was a mite touchy about her barrel but that went away after the round of Nexium. Teeth fine. Shots worming etc all UTD. Was shod on the fronts temporarily but we took those off as she kept loosing them…was not shod at track and only had them on due to rocky trails at previous home. Her feet are remarkably normal for a TB. I should mention these symptoms were popping up long before we took the shoes off about 3 months ago.

Any thoughts as I prepare to embark down this road? Vet suggested spine, suspensories, SI/pelvis, maybe muscular issue. He said that she did not seem neurological but of course, I’m worried about EPM/EDM and so on. She’s had no pasture incidents that I am aware of in the time she’s been here. And, all “work” has been low key, let’s bob around the well footed arenas and learn about contact and bend sort of stuff. No jumping or anything strenuous…not even ground poles.

Can you get an ultrasound of the stifles and SI? Based on your description, I’d be thinking of those areas and soft tissue if it were my horse.


That’s on the docket for her full workup, What would cause soft tissue injury on both stifles to an equal degree? Is she compensating for another issue, I wonder.

Is there Lyme in your area?

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I brought up Lyme. It’s not prevalent here, nor in the next state over where she came from. But anything is possible. I’m going to ask they look for it still.

Bunny hopping and hind leg handling etc make me thing SI joints. But some of the other stuff could be neuro. Or could just be heightened anxiety due to pain. I’d probably start with SI ultrasound if neuro exam is normal, as SI seems most obvious to me.


I’d strongly suggest adding a gastroscope to your workup if you can. My gelding presented very similarly last year. Local vet was convinced it was SI. My trainer and I weren’t sure, so I decided to send him to New Bolton for a comprehensive workup.

Diagnostics including lameness locator revealed nothing more than thin soles and flat/negative hind angles. The vets at NB were puzzled until they scoped and got a look at his stomach. Grade 4 glandular/pyloric ulcers. Once we treated the ulcers and fixed his feet, his hind end soreness started to resolve. They develop some really incredible compensatory movement when they have pain anywhere, but especially in hooves or stomach.


I’ll sign her up for a scope, I’ve heard that before. Ulcers would certainly be one of the better scenarios here.

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Lyme and ulcers can make them do weird things, and both can make their weirdness inconsistent. Good today, terrible tomorrow, etc.

The Cornell test for Lyme is pretty fast and inexpensive, it cost me ~$100 and I got results in three days.

Maybe put her back on Nexium and see if she improves? It’s a low cost way to start before going down the diagnostics rabbit hole.


Glad you’re looking at stifles and SI. As long as she’s there, I would recommend a once-over on muscles from lower back through the hamstring group with ultra sound.

Take a look at Dr. Valberg’s work on MFM. She’s got some great information. I have not had my horse tested but there is a big difference in how he shows up based on whether he’s been on the pellets she developed (amino acids).

Good luck …!

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Some good advice here. I would also add X-rays of the back. Sounds like the pretty classic kissing spines behavior my horse exhibited- random sudden explosive behavior in hand/under saddle/on lunge. On and off sore suspensories, hocks, stifles from an altered way of going trying to protect the back. Originally thought he might be neuro - he had a toe drag that went away periodically. Unfortunately it is prevalent in TBs. It’s good to rule it out anyway and to have a baseline for any future X-rays you might get down the road. Might be a good idea to X-ray the back feet in addition, to see what the palmar angles are as they can also affect the back and SI. Good luck!


i’d be getting back and neck xrays, including checking for the c6/c7 malformation which needs an xray from a specific angle


It sounds very complex, whatever it is, and I think you’re right that there may be an original, underlying cause and then some secondary soreness as compensation.

Kudos to you for trying to get to the bottom of this.

I’d definitely have the vet do the Cornell lyme test, as another poster mentioned. Personality changes (even temporary ones), occasional lameness, general body-soreness, etc. are all associated with lyme (as well as with other diseases). The Cornell test is relatively cheap and fast, and vets who don’t see lyme disease often sometimes just don’t think that it’s an issue in their region. I’ll also mention that there are other tick-borne diseases that often have the same shifting symptoms as lyme.

Good luck!

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I would pull blood for Lyme and EPM before shipping in to the clinic. If those are both negative, I’d start by ultrasounding the proximal hind suspensories.


Have a listen to this also:

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Epm, Lyme and just treat for ulcers is what I’d do first. Epm can cause all sorts of weird behavioral symptoms. It doesn’t always present as severe neurological crap.


C6/7 malformation (or outright Wobblers) and PSSM2 are things I’d look into, after ruling out Lyme.

So my order would be - Lyme test, a 7-10 day trial of Nexium (or generic), PSSM2 test

I’d want to see the hind feed rads - it’s amazing how many vets don’t see NPA :frowning:


I see JB already mentioned it, but I came to suggest checking palmar angle in her hinds! This guy provides excellent data that often connects to lameness/soreness issues that is difficult to pinpoint:


There’s a REALLY good post from him on May 4, on NPA.


THANK YOU everyone, I am compiling a list (with a lot of your suggestions) so I can be as prepared as I can be. COTH shining through again.

I just want her to be comfortable, but as a grad student needing to help support a parent with cancer, I don’t have a ton of resources to spend chasing a mystery. I have a budget for emergencies, for routine vet care, etc but not for endless specialists nor even really significant time spent at the Big Guns if our clinic can’t find anything (for us this would be UC Davis). I hope this doesn’t come across as callous but it is adding to my stress. Push comes to shove maybe she can come live at home with our three retirees and I will take a riding break for a while until I recoup the bills.

I can’t help but feel a bit burnt out from the whole thing. This right on the coat tails of the melanoma calamity with a previous new horse (I knew what I was taking on with her, and this was pre catastrophic illness diagnosis with said parent…so with this TB mare I tried to do everything “right”). Oh, life with horses!