LTR Hypoplasia - Nature, Nurture, Bit of Both?

UPDATED in latest post. :slight_smile:

Heads up: Long story (to provide background/context) with a sad ending. Opinions wanted.

I’m on second homebred generation and have run into a major health issue - and am very motivated to better understand the heritability, cause(s), and whatever else I can do better in the future.

Grandma Mare is a jockey club TB. I bred her to lovely WB stallion from a highly respected breeding facility. (Additionally, this stallion has a good OCD score indicating he is unlikely to pass on OCD. You may see where this is going.) Grandma Mare is still with us, but will likely be euthanized this fall at the age of 29 due to advanced arthitis in her front knees. (She started life with early racing followed by barrel racing. Ugh.) Otherwise, Grandma Mare has lived a long, sound life with no indication of heritable issues.

Grandma Mare produced one foal for me by the lovely stallion - let’s call the foal Heart Horse. Heart Horse took after her sire and has been a solidly healthy, sound, beloved mare. When Heart Horse was about 13, I decided to breed her (I would love a clone of her, but a foal from her might be the next best thing). I bred Heart Horse to another (unrelated, naturally) lovely WB stallion from a highly respected breeding facility. (This stallion, also, has a breed OCD score indicating he is very unlikely to pass on OCD.) She didn’t take the first year but did the second year, and foaled a handsome colt.

Handsome Colt had some tendon laxity at birth, being ‘back on his heels.’ Heart Horse also had this at birth to some extent, but hers self-corrected within ~48 hours. Handsome colt remained significantly back on his heel bulbs. We eventually opted for glue-on foal shoes with heel extensions to correct this, and he responded wonderfully to the shoes. Our farriers and vet worked together to keep the corrective shoes on through 2-3 shoeing cycles as he grew. Afterwards, his angles appeared solidly corrected, he went barefoot with regular trimming, and seemed to have no issues. Handsome Colt continued to mature into, well, a VERY handsome colt with a teddy bear personality.

At about 10 months, Handsome Colt presents with swelling in the left stifle. Big sigh - he’s a very large (mom is big and tall, dad is big and tall), gangly, fast-growing yearling. Gosh darnit I may have been heavy-handed with the grain over the winter. OCD diagnosis fits like Cinderella’s glass slipper. Local vet comes out and we radiograph the left stifle in the barn, and see a low-density area that looks like an OCD. Local vet refers us to state university.

We get an appointment about 6 weeks after initial radiographs at state university and bring in Handsome Colt. Vet at State looks at him and agrees, yup - likely OCD but don’t panic - they do a gazillion OCD surgeries every year, prognosis is very good, we caught in early. Books him in for OCD surgery the following morning. Pre-operative radiographs reveal we are not exactly dealing with OCD. Instead, we are dealing with severe lateral trochlear ridge hypoplasia. The ridges that should align and track the patella are… gone, basically. Surgery is cancelled, as there is literally not enough bone left to work with. Stifles are basically crumbling. The left stifle’s “skyline view” image of the trochlear ridges is described as a “ski slope,” and he could luxate the patella with one goofy step at any moment. The right stifle is similar but not as far along the progression. Hocks showed no OCD. The vet is on-board with us to try to maintain some level of pasture soundness with him, but early arthritis is basically guaranteed. Handsome Colt is brought home, where he remains happy for the time being. He’s in a pasture with a buddy, on Equioxx, I’ve already run one course of Adequan, and I’ve orderd “KER Duraplex” because I don’t know. Fortunately, I have my own farm with plenty of room, so I’ll try to keep him comfortable as long as I can.

SO. My theory is, I didn’t get the glue-on corrective shoes on early enough, and he slammed around too much too hard on soft little baby stifles recieving force at all the wrong angles. I’m absolutely gutted that possibly my overly-conservative management approach to this may have doomed my colt. There seems to be little/no family evidence of OCD, though perhaps it could sneak in from the TB mareline or just be a sad fluke.

What do you think? Have you every encountered anything remotely similar? Would you even consider re-breeding the mare, to a different stallion? (Not that I am planning on doing so in the forseable future, more a hypothetical question.) Would you interpret this as an OCD-like condition, with some genetic basis? Would the propensity to produce offspring born “back on their heels” with lax tendons be the deciding factor for you? Would you continue to maintain a horse who has some very real risk of luxating a patella at any moment, or would the risk of that occurence be enough to prompt euthanasia?

Maybe this article can answer some of your questions:

It sounds like a sex-linked trait (all colts that were affected). It also appears to be recessively inherited in ponies.

I think you would probably be okay breeding to a different stallion.

At any rate, I am very sorry. I don’t think this is something you could have foreseen or prevented.

I would find it very difficult to euthanize because he is not currently suffering. But I would certainly worry about him luxating when you aren’t around to intervene. Did the vet that examined him recommend euthanasia? You can always euthanize at a later date when the arthritis progresses.

I would probably go ahead and re-breed the mare, and have a plan in place for your next foal in-case something goes wrong. Maybe breed to a smaller stallion, and try to avoid a rapidly growing foal.
If it is a recessive trait that only presents under the right environmental conditions, then I think your next foal will probably be okay.


Ah yep - I’ve already read that paper (trawling the interwebs for resources since the diagnosis) and that is definitely the most similar to what we’ve got here. I can’t quite put my finger on why but those examples struck me as decidedly more congenital in nature. Both lovely WB site and grandsire have very large foal crops on the ground, and I could find not a smidge of this type of hypoplasia documented in WB circles. I just feel like if this was a thing, even a rare recessive thing, there’d be another one out there… I don’t know, something still makes me feel that there was an ‘early traumatic’ element to my guy’s diagnosis. (Though on the other hand, I could find no documentation linking tendon laxity at birth to later hypoplasia, regardless of corrective shoeing timelines.)

Euthanasia was certainly on the table in the discussion with the diagnosing vet, but in her words, “you can’t un-euthanize” so I don’t need to rush to that. His discharge report says something along the lines of “it’s reasonable to continue to support him medically” and that it’s encouraging he remains bright and fairly comfortable for the time being. I do have him in a somewhat larger pasture than the vet would probably like, but the footing is good and it gives enough room for him to loaf with his favorite buddy. (They picked at each other too much in the smaller paddock I tried first.) I guess I’m aiming for quality of remaining time over quantity. The vet was understandably reluctant to give long-term predictions (aside from concluding no athletic potential) based on lack of similar cases in the literature. I do realize that his young joints are not yet feeling the ravage of the impending arthritis just yet, and when they do, QOL is probably going to decline regardless.


I am sorry you are dealing with this. What an unexpected turn and not what you want to hear when prepping for OCD surgery. :frowning:

I have never encountered something similar. After all you’ve said, I would consider re-breeding the mare to a different stallion. I would not interpret it as an OCD-like condition. This is something else and it is likely your HC was born with this defect in the trochlear ridge. No, producing offspring born back on their heels/lax tendons would not be a red flag for me. Your last question, only you can answer. You are the one that live with him and knows him best.

Frankly speaking, even if there was a congenital issue that a very well known stallion was prone to pass on, you would never know. There’s not much transparency out there until people make a fuss. Have you contacted the stallion owner?

Are you suspecting the grand-dam because her daughter (HH) was born with some tendon laxity, and then so was HH’s foal HC? Tendon laxity is fairly common in newborns and typically self-corrects. That to me would not signal granddam culpable for HC’s issues.

What was HC’s management like from the time he was born until now? You mention he may have gone through a big growth spurt?

I’m with others, I don’t think this is something you could have prevented or known about. Sometimes, things are just not born right even when both parents are perfect; and, just because they are born that way does not mean it is a heritable disorder. Congenital does not mean heritable. I hope you can give HC a peppermint for me, that is such an awful diagnosis.


How terrible. I’m so sorry. Breeding is not for the faint of heart.

I agree with others, I’ve never heard of a correlation between this and tendon laxity, and I even tend to deal with laxity quite conservatively without issue. This also seems to me to be congenital, though I think rare.

I think you are in somewhat uncharted territory is regards to inheritability. I think it depends on if you can gut going through this again with rebreeding if this does potentially occur again, even if the risk is low.

I would also allow HC to continue living a quality life if you are able to monitor him and catch a luxation of the joint quickly. But I’d certainly understand if you wanted to go the route that would prevent that. I think you are justified in either approach.

I’m really sorry you are going through this. If you happen to find any more information regarding the case, I’d love it if you shared. Fingers crossed for you all.

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My theory is, I didn’t get the glue-on corrective shoes on early enough, and he slammed around too much too hard on soft little baby stifles receiving force at all the wrong angles.

I very much doubt this, It sounds genetic (either inherited or spontaneous) as a particular structure did not develop on both sides.


Frankly speaking, even if there was a congenital issue that a very well known stallion was prone to pass on, you would never know. There’s not much transparency out there until people make a fuss. Have you contacted the stallion owner?

I have not yet, but likely will - we just got the diagnosis a couple weeks ago and I’m still kind of processing/mourning. I honestly don’t think the stallions have had anything to do with this, no hard feelings at all towards the very professional stallion owners; I just hate to share the bad news. I’ve also been in just agony over the idea that something I’ve done (grain choices? timing of corrective shoeing?) could’ve been the thing that’s doomed Handsome Colt.

Are you suspecting the grand-dam because her daughter (HH) was born with some tendon laxity, and then so was HH’s foal HC? Tendon laxity is fairly common in newborns and typically self-corrects. That to me would not signal granddam culpable for HC’s issues.

Almost less like I want to point the finger at an individual horse in the pedigree, and more I want to question whether breeding for a big, long-lined, fast-growing phenotype, with the knowledge that the babies are/may be displaying tendon laxity at birth, and maybe wonder if those factors are not… indicative of the most robust individual? I don’t know, nothing causative, of course. Breeding the mare again in the forseable future is not really in the cards anyways; I don’t think I could stomach it if I produced a second baby with such serious issues.

I’m going to attempt to attach the state university’s radiographs, if that changes anyone’s answers. LH_4 and RH_4 are the “skyline view” shots.

I honestly think that comes with the territory of breeding large WBs. Tons of foals have laxity but I’ve never seen it result in this. If you were dealing with OCD and were questioning husbandry, I’d think absolutely, feed or environmental factors could be the cause. But I really feel this is congenital. I don’t think you are to blame.

To be honest, I was expecting a bit worse with radiographs. I’ve seen much worse in small animals. I certainly see the issue, but the rads make me lean more towards QOL management.


Yes, I’ve had a GSD whose hip joints were flat as pancakes. She was stiff but kept her active and well-medicated until we lost her to hemangiosarcoma. Sometimes the animal just copes. Heartbreaking disappointment in a young horse though :frowning:

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Interesting update: I finally bucked up and reached out to the stallion station with an update - that we love the Handsome Colt, that he’s gorgeous and has the temperament of a lamb, and sadly that we’ve run into this terrible health issue. I attached his University vet chart/write-up and all the radiographs they took there. The breeding director wrote me back immediately with concern, and shortly thereafter showed the rads to their own vet surgeon, who (informally) arrived at a very different conclusion than the University vet. They said they saw OCD cysts, sure - but no hypoplasia. The breeding director gave me the name of a boarded radiologist that they have worked with before and really like, and encouraged me to get a 2nd opinion.

I’ve already reached out to them ( and am waiting to hear back about next steps there.

So. All kinds of feelings.


Best of luck! I have not had much luck with vets or doctors diagnosing anything accurately so a second opinion is always a good idea. I would probably pick a 3rd vet that is unrelated to the breeder in any way.

I had a vet look at x rays and tell me that my cat had an obstruction and I should probably euthanize. Said cat recovered after 5 days of home rest and my forced attempts to get fluids in her with a syringe. She lived another 5 years after that. Best guess was she had pancreatitis but it could have been IBD. Or maybe a hairball that was blocking something temporarily? Probably never know… Another cat they wanted to do exploratory surgery on. It turned out he had lymphoma. If I had done surgery we would have diagnosed it sooner, but at what cost to the cat? He lived another year before passing when the cancer went to his kidneys.

At any rate, I would definitely get a second opinion, even if the first vet turns out to be right, at least there won’t be any doubt on the diagnosis.

Well, I’d like to provide an update on the aforementioned second opinion, but I’ve had a heckuva time navigating the process. The recommended boarded radiologist says he “bills through the local vet for legal reasons.” My local vet practice has straight up declined this, and the State University is expressing some major reservations. I’m somewhat unclear how this is supposed to work… Does the vet pay the radiologist, and then I pay the vet? How does this typically go? I have the radiographs myself/a link to download them in DICOM format; it’s billing that seems to be the issue. Any guesses what a second opinion would generally run, even? I haven’t gotten any numbers yet from any party.

You would have to call around and ask for quotes. My friend wanted a lameness exam done on her mare. They found out it was cheaper to haul her to a lameness specialist then go with the local vet.

All the vets I have used charge you when you leave the clinic for the total. I have never had them not do that. Probably just need to wait on them to sort it out or send a bill in the mail. If the local vet does not want to collect payment for the radiologist, then the radiologist needs to ask for payment directly from you. Unless you are waiting on insurance payouts? Either way, I would expect a bill to arrive in the mail eventually.

Don’t feel bad. I owed money on a hospital bill and it only took them about 18 months to send me a bill in the mail. Yes that is how far behind they were on collecting payments. They will get around to charging you eventually.

They should be able to put together an estimate on what your charges will be on a second opinion. If not, find a different vet. Sounds like they are short staffed.

UPDATE: I obtained a number of second/third/fourth opinions, and they were somewhat mixed but all more positive than the original diagnosis. Here’s the rundown:

  • I did get the boarded radiologist’s opinion, which was… brief and straightforward. He concluded significant osteochondrosis of both stifles. No mention of “hypoplasia.” Surgical correction strongly recommended.

  • I sent the radiologist’s report and original university to report to a different, slightly-less-nearby state university. They reviewed remotely, and concurred - surgery recommended, ‘didn’t really see hypoplasia,’ didn’t feel the risk of luxation was considerable, think about PRP or IRAP.

  • The stallion owner, independently, connected me with a vet at a large, ‘big name’ private practice in their area they’ve worked with before. That vet, also, strongly recommended surgical correction and felt there was at least some potential for athletic recovery, given the colt’s age.

I circled back with the original university (felt a little funny doing so… but it would be such a haul to get the horse out to a different facility, though I would do it if we need to) with the radiology report and the big-name clinic’s vet’s opinion, and inquired (super politely!) whether we should reconsider the risks/benefits in pursuing arthroscopic surgery…

…and I got a call-back the very next morning, from the more-senior vet there that we had originally been trying to work with, but upon arrival last time we were actually placed with a different vet. (A much younger, less-senior vet, though I’m not sure that’s relevant.) This Dr. explained, ‘no no, we just didn’t want to do surgery last time because we were afraid his bone would be too soft at that age, and we’d risk removing too much material during surgery. Now it’s probably fine, so give us a call early next week and we’ll get you in the earliest surgical opening!’ < This was not at ALL the conclusion I came away with from my original debrief with the previous vet there, whereupon “euthanasia was definitely on the table,” the idea that any iffy step and he’d luxate that patella, and a discharge report stating “no follow up necessary.” :thinking:

Anyways - we’ve got a surgery spot for October 19th for the left stifle. We’ll have to do the right stifle at a later date. It seems, understandably, impossible to say what the long-term prognosis really is. The colt is SO sweet I can’t not pursue every possibility for him. Please, please, send some jingles our way!!


Wow, what a roller coaster ride! Definitely sending jingles your way!

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Reaching out for an update. How did surgery #1 go?

Well… It didn’t. A few days before the scheduled surgery, the colt bumped his eye, which developed into a corneal ulcer. The vets (understandably) recommended postponing the surgery for fear that general anesthesia would make the ulcer worsen. Now, we’re waiting for their next surgery slot to open, which probably won’t be until Jan/Feb. It’s always something!


It IS always something. Fingers crossed for your colt. Please post an update when he has surgery.

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Tiny non-update update: His eye is FINALLY better! We got the “sub-palpebral lavage system” thingy finally removed from his eye! He is in a very small turnout/runout setup and much happier… And we have a new arthroscopy date of January 25th!

Please keep jingling :grimacing::crossed_fingers::crossed_fingers:


Back again with another update, in case anyone may still be following. We did bring the colt back to the state university at the end of January for our next scheduled attempt at an arthroscopy procedure. Fortunately, the old-timey head vet who was scheduled to do the surgery was there at drop-off and was very impressed by how comfortable the colt appeared.

We - myself, the surgeon, and a couple techs - took the colt to their arena area and jogged him; the vet seemed very encouraged by that to the point that he suspected arthroscopy would potentially do more harm than good! To gather more info, they shot pre-op rads on both stifles and we all debriefed in one of their little evaluation rooms. Interestingly… the OCD lesions do appear to be self-healing to a degree! The diagnosis is still not great… the old-timer vet thought “we might get a trail horse out of him.” But, surgery is apparently not indicated and we should basically keep on keeping on - turnout in small areas with good footing, trying to avoid aprupt/explosive movement, likely re-radiograph sometime in the spring or summer to see how things are progressing.