DSLD, Nuchal Ligament Test, Shockwave.

[mvp]

I have seen horses with various stages of DSLD for a long time. I have seen really end-stage stuff in large, well-bred WBs. The three I’m thinking of were of the heavy/old fashioned style that didn’t seem to have lots of TB blood in them. Back in the early 1990s, Cornell University stood a stallion for a well-known Northeast owner who had some fetlocks so low that even anyone who had never heard of DSLD would notice his stance. Of the other two ridden WBs, one owner was diligent and knew what she had/what she was doing; one really did not and rode her mare way beyond what I think she should have and continued to think of this mare as more sound than she was. Within 60 days of pasture retirement, the “mare just didn’t get up one morning.” That pissed me off.

I have seen early stages (I think) in horses as young as 3, with hind pasterns that strike you as just a touch “too horizontal.” You look up the leg and can appreciate that the hock looks a tad straight sometimes. And I didn’t think to look for toe-dragging, but IIRC, it was there in this horse, too. It’s subtle, but keep your eyes peeled for horizontal pasterns and straight hocks; it might be the earliest sign you see.

Most interesting, I met another horse who didn’t heal well from castration (at 11 years or so); developed hind end suspensory problems, which were treated and managed diligently for a long time… to no avail; lesions kept showing up in ultrasounds meant to check healing. And this horse developed a sway back, too.

What I make up about that last case is that all connective tissue is affected… so any ligaments doing significant mechanical work will start to fail. In a big, round-bodied horse like this (he was of a baroque breed), I think the collateral ligaments in his spine were affect just as his suspensories were.

Back in the day, the physiology of this was explained to me as the body just not making repairs to those microscopic lesions made in ligamentous tissue during the normal stress and rebuilding of exercise that results in denser, stronger tissue. With these small repairs not made between workouts, using these ligaments was like fraying a rope: You might not see the effects at first, but by the time you do, you can’t fix it. Reading Lord Helpus’ helpful article, I’m not sure this is the correct understanding to the physiology.

Either way, I hope we do find a solid genetic marker for this disease and eliminate it from the breeding population. I’m so glad there is that nuchal ligament test. But it’s going to make for some awkward requests during PPEs.

[DFL]

You may have already seen it, but this is another good article: https://thehorse.com/148171/researchers-find-link-psd-development-straight-hocks/

[JB]

PSD related to straight hocks is different from DSLD/ESPA, just in case anyone was thinking there’s a connection. ESPA is systemic and genetic. PSD can be the result of conformation (straight hocks), or injury and/or over-use. Injury to one leg, causing problems there, can result in over-use of the other and subsequent suspensory issues.

[SusanO]

OK I read the letter from Dr. Allen that you posted. I am not getting that he thinks the horse has DSLD. My impression from what he has written is that he wants to rule that out before he suggests a treatment plan for the horse. I am sure that he is very methodical in his approach and that is partly why he is so highly regarded as a vet. I think getting the test before you proceed is very wise. Not just to decide what to do but to give you some closure - does he have a genetic disease or not.

I have a friend that just retired her 4th level horse with suspensory issues. He does not have DSLD. It was very hard to figure out what was wrong with her horse. She is an excellent horseman and did not realize what was going on with the horse. People told her and convinced her that the horse not wanting to work was a “work ethic” problem and just the horse’s quirkiness. The vets didn’t really see much at first. Then she went to Florida to train with someone that was not just a good trainer but somebody who had a great eye. That person looked at him and said - Your horse is not being balky - he is lame. I don’t remember what all she tried to get him sound but he is now retired. So these things can be hard to see and diagnose even with good vets on board.

[2tempe]

DSLD is a progressive degenerative condition primarily affecting the branches of the suspensory ligaments. This disorder causes mild to severe lameness either bilaterally or quadrilaterally, and can occur in the absence of athletic activity. Clinical signs can range from stiffness in gait to an overt lameness. Moderate to severe pain is often evoked by palpation of the suspensory ligament branches. There is enlargement and thickening of the suspensory branches, and a positive response to distal limb fetlock flexion.

I retired a 15 yr old WB mare last August. The above description could have been written by my vet, bilateral . He cautioned me that her issues “could be” degenerative, and thus a major ( but not only) factor in the retirement decision. He also told me that the fetlock drop is a gradual thing UNLESS something sudden damages the ligaments and then it could be over in the snap of your fingers. So I wait.

[DFL]

Sorry, I don’t mean to hijack but one of my biggest problems has been trying to decide if it’s the right decision to keep my horse in work. He owes me nothing but he likes having a job and in fact he looks worse off when he’s had time off and loses conditioning. But I can’t help thinking that it could be causing more damage (even though it’s probably less than what playing in turnout causes). @2tempe, what else factored into your decision to retire your mare?

[findeight]

One of the few advantages of getting old is you have a wider variety of experience and observation to recall that might be helpful to others. I’ve seen this condition over the years and what was probably this back before there were any decent diagnostics. No way to differentiate between it and similar appearing conditions caused by injury and/or bad conformation until not that many years ago.

In my observation and experience, it can occur in any breed but seen it more in bigger bodied horses and TBs. That pretty much describes the WBs as most are studbooks or registries and not unique breeds so not willing to pin it on a specific " breed".

That said, I remember back in the late 60s there was an Arab with some type of serious genetic defect, it was shed row gossip but it’s babies (that lived) were pretty and won so he kept getting mares…don’t recall how, or if that was resolved. Then in the 70s that gossip was something was bad wrong with the Impressives but they were pretty and won so he kept getting mares until the owners finally pulled him. Yet decades later some breeders were still breeding that lineage because " you couldn’t win Halter with an N/N" and playing fast and loose with what was on the breeding certificates. DNA finally stopped (most of) that.

I really doubt the WB books would be immune from greed as long as the offspring won and sold well. It would take some solid statistics over a good many years to establish even the possibility. And let’s not forget AI has allowed each stallion many more mares of varied bloodlines so, hard to point fingers.

[2tempe]

DFL: working backwards: The mare had recently come back from a lease (was fine then). She is not my primary horse so I didn’t want to put her thru the rehab process only to have it go south again. Unlikely that anyone would have leased her with this cloud and it would have been a worry for me.

Prior to this, she has had a pile of other issues over the last 5 years or so. Stifle inflammation. Major wither event due to “significant trauma”. Two surgeries for large colon displacement (one left, one right). A nasty case of anterior enteritis.

I’m done with vet bills. I’m done with trying to have her be a dressage horse. I’m done with waiting for the next shoe to drop. SO: She is at a friend’s farm, good care, good farrier, equine friends and not a care in the world. Whatever happens, happens. And my expenses have decreased.