Suspected PSSM-2 and elevated selenium levels

[Squirt]

HI all!
So my main riding horse (14yo OLD/Arab Stallion) has been having these weird episodes the last month, and TBH probably before that in years past that I just didnt connect. What happens is that he warms up great but after about 20 minutes he gets resitant and “twitchy”. By twitchy I mean that he ripples his muscles (Usually on one side) like flies are bothering him but there is nothing there. In the past I chalked it up to saddle fit needing to be tweaked or sensitivity to neoprene girths (He is kind of a princess) and looking back it happens usually in the spring and fall. But now it has happened in my newly fitted dressage saddle, my western (which he has never had issues with in the past) AND when I rode him bareback (Because I was too lazy to tack him up). It’s gotten to the point where he was biting at my leg and bunny hopping into the canter. But not all the time?

I initially thought that maybe his tummy was ouchy so I put him on a buffer (not omeprazole) ulcer supplement that has helped in stressful times in the past. No real difference. I had the massage therapist out because it DID feel like it was muscular and she said that she didn’t feel anything really out of whack except that his hind end was really tight which was unusual for him. So I got to thinking and googling and texting my vet. I asked about PSSM 2 (cause hes not really the right breeds for type 1) and she pulled some blood to check E and Sel levels and to rule out Lyme.

Good news - Neg. for Lyme, right in the middle for acceptable for Vit E. Bad news - Elevated levels of selenium? How is that possible? I don’t supplement, he gets the low end of recommended commercial feed and I grow my own hay in the Great Lakes region which is notoriously deficient in soil selenium levels.

I need to have a talk with my vet on where to go from here. We already agreed to start treating him like a PSSM horse which isn’t too much different from how I managed him in the past. (I switched him from a 20.5% NSC to a 11.5% NSC grain) She’s not comfortable doing a muscle biopsy and I’m honestly not too enthused about having it done. I have other vets that I can reach out to do the biopsy but Its not like it would really change our response. I’m actually less than 2 hours away from MSU where Dr. Valberg is located but I am a stay at home mom with limited resources and going to state is EXPENSIVE!!!

Anybody have any ideas about HOW he could have elevated selenium levels? Can that explain the symptoms?

What about adding in DMG or Magnesium to his rations?

Honestly I just want my horse to be comfortable.

[4horses]

The problem with pssm 2 is that it is a catch all diagnosis…meaning different diseases can fall under the umbrella of pssm type 2.

This video is heartbreaking, but shows the struggle with diagnosis:

https://www.youtube.com/watch?v=rlx_BLOe7Uw&t=797s

My beautiful paint mare might have pssm type 2. I’ve had her for 15 years. Even as a 2 year old she wasn’t quite right behind. She couldn’t hold her lead behind. Here’s a video:

https://www.youtube.com/watch?v=OBiCbfhFN3Y

I had multiple vets look at her. Told to try pentosan, adequan, joint injections of stifles, and pelvis, told to get a nuclear scan. For years she did okay under saddle as a walk-trot horse with the occasional canter. One hot summer day she went down on a trail ride. I got her up and she went down again. I blamed the excessive temperatures. It happened again the next summer, and again this spring. Each episode lasted 20 minutes or so and she recovered without any intervention. I had muscle enzymes pulled and they were in the slightly above normal range. The vet said she didn’t think it was tying up and didn’t think it was pssm type 2, but I’m at a loss to explain the matter. She does not have muscle tremors. She stops, gets in a urinary stance, before finding a spot to lay down.

Today my friend’s mare did something similar. Tennessee Walking horse. We were riding and she didn’t want to hold the canter. My friend wanted me to watch her. She would break into a pace and I remarked that she reminds me of my mare, as both move stiff behind, even at a walk. Both have a very rough hoppy canter behind.
”‹”‹”‹”‹
”‹Then she kept stopping on the way back. My friend thought she needed to pee. Then she laid down. Her symptoms look like my mare’s. Is this colic? Or pssm related? I don’t know, but visually it is very similar. We got back to the trailers okay and she seemed okay. My friend says she is prone to colic so maybe this is just a colic?

Because pssm type 2 has no effective treatment, and a very invasive diagnostic test, not many people test for it. Certainly the diet is worth a try. I had a mare on lease with type 1 pssm and that mare had the worst muscle tremors you have ever seen. Totally different presentation and she showed symptoms despite being on a high fat diet. Head to the ground, muscle tremors, and a tucked up abdomen.

My mares diagnosis is a mystery. The only thing I have noticed is that the more frequently you ride her (2-3 hours for a couple days), the better she moves behind. Still no idea what causes an episode other than she seems to do poorly when worked during the summers.

Visually these episodes look very similar to colic, so it’s entirely possible people are breeding horses that have pssm type 2 and not recognizing it. The equisec testing for pssm 2 would be great if it was affordable and if they released their research to be peer reviewed. Right now they claim to be able to test but there’s no published information as to how often healthy horses test positive. Without publishing their research AQHA and APHA aren’t going to require testing within the breed. This definitely is a big problem, as we need the research to be published and proven without a doubt.

Get muscle enzymes pulled at least a couple hours after an episode.

[leheath]

I have a horse who used to get very twitchy with muscular tightness when she was younger and it was only ever really obvious under saddle. For her, magnesium supplementation was absolutely the answer. I used SmartCalm Ultra. The good news is that it won’t do anything if they don’t need it, so trying it can’t hurt.

Some of your horse’s symptoms could be attributable to PSSM 2, but they could also be attributable to many other things (that is the problem with diagnosing PSSM 2). For example, my horse has SI issues and has similar symptoms, including the tightness in the hind end. Kissing spines can also cause similar symptoms. @4horses is correct that the genetic test is, at the moment, not helpful because there is no available data regarding how many markers are needed for a definitive diagnosis and how many are observed in healthy horses.

The high selenium is weird. However, typically there is an acceptable range associated with every blood test (human and animal) and each individual will naturally fall somewhere in that range. Some will fall just outside it naturally and normally with no ill effects. My thyroid T3/T4 levels are “normally” very low such that they can double and still be in the acceptable range, yet I will have significant symptoms and I do need medication to alleviate the symptoms and return my levels to “my normal.” Since I’m assuming you’ve never tested your horse before, it’s hard to say if the selenium result is significant or a red herring. It may be worth looking at the acceptable range and where your horse’s level fell in relation to it. One of the most obvious symptoms of selenium toxicity is hair loss - does your horse have any signs of hair loss either in their coat or mane or tail? Poor/crumbling hoof quality can also be a symptom of chronic selenium toxicity. Unless your horse has these symptoms, I am guessing the elevated selenium is a red herring.

[zorion]

For what it’s worth, EquiSeq now offers a hair sample diagnostic for PSSM 2. I think it runs about $300 and it will also tell you which variant you are dealing with.

[Equkelly]

@4horses

The problem with pssm 2 is that it is a catch all diagnosis…meaning different diseases can fall under the umbrella of pssm type 2.

This video is heartbreaking, but shows the struggle with diagnosis:

https://www.youtube.com/watch?v=rlx_BLOe7Uw&t=797s

My beautiful paint mare might have pssm type 2. I’ve had her for 15 years. Even as a 2 year old she wasn’t quite right behind. She couldn’t hold her lead behind. Here’s a video:

https://www.youtube.com/watch?v=OBiCbfhFN3Y

I had multiple vets look at her. Told to try pentosan, adequan, joint injections of stifles, and pelvis, told to get a nuclear scan. For years she did okay under saddle as a walk-trot horse with the occasional canter. One hot summer day she went down on a trail ride. I got her up and she went down again. I blamed the excessive temperatures. It happened again the next summer, and again this spring. Each episode lasted 20 minutes or so and she recovered without any intervention. I had muscle enzymes pulled and they were in the slightly above normal range. The vet said she didn’t think it was tying up and didn’t think it was pssm type 2, but I’m at a loss to explain the matter. She does not have muscle tremors. She stops, gets in a urinary stance, before finding a spot to lay down.

Today my friend’s mare did something similar. Tennessee Walking horse. We were riding and she didn’t want to hold the canter. My friend wanted me to watch her. She would break into a pace and I remarked that she reminds me of my mare, as both move stiff behind, even at a walk. Both have a very rough hoppy canter behind.
”‹”‹”‹”‹
”‹Then she kept stopping on the way back. My friend thought she needed to pee. Then she laid down. Her symptoms look like my mare’s. Is this colic? Or pssm related? I don’t know, but visually it is very similar. We got back to the trailers okay and she seemed okay. My friend says she is prone to colic so maybe this is just a colic?

Because pssm type 2 has no effective treatment, and a very invasive diagnostic test, not many people test for it. Certainly the diet is worth a try. I had a mare on lease with type 1 pssm and that mare had the worst muscle tremors you have ever seen. Totally different presentation and she showed symptoms despite being on a high fat diet. Head to the ground, muscle tremors, and a tucked up abdomen.

My mares diagnosis is a mystery. The only thing I have noticed is that the more frequently you ride her (2-3 hours for a couple days), the better she moves behind. Still no idea what causes an episode other than she seems to do poorly when worked during the summers.

Visually these episodes look very similar to colic, so it’s entirely possible people are breeding horses that have pssm type 2 and not recognizing it. The equisec testing for pssm 2 would be great if it was affordable and if they released their research to be peer reviewed. Right now they claim to be able to test but there’s no published information as to how often healthy horses test positive. Without publishing their research AQHA and APHA aren’t going to require testing within the breed. This definitely is a big problem, as we need the research to be published and proven without a doubt.

Get muscle enzymes pulled at least a couple hours after an episode.

This was interesting to read. My mare has also been doing some things that made me tilt my head and I’ve had pssm type 2 in the back of my head for a few months. The weirdest thing was when I picked her up from the he hospital from a bad colic her whole body was shaking. I know she was anxious about being hospitalized but I’ve never seen her whole body shake like that. And the only time I’ve ever seen any horse shake like that was during really cold weather. The vets explained it as anxiety but I’ve never seen a horse do that from anxiety so I don’t know.

My mare also has ALWAYS been a toe dragger but she’s 4 so my vet was kind of thinking she’ll grow out of it. Plus she mostly just does it in the pasture, but when she’s actually working u/s she picks up her feet fine.

Then a few weeks ago we had a summer snow storm, (thank you colorado) and it went from being 100 degrees one day to cold and snowy the next. I gave her some electrolytes beforehand and blanketed but she was doing that muscle “twitch” thing. Not shivering, not tremors, but like a fly was biting her only there were obviously no flies because it was snowing and she was blanketed.

Problem is, I manage her not that differently than I would if she was positive for pssm2. I feed a low NSC grain and not very much, grass hay, 24/7 turnout, and shes never really been in “hard work” since she’s so young.

Not enough for me to want to order a whole diagnostic panel but it’s in the back of my mind.

[leheath]

@zorion

For what it’s worth, EquiSeq now offers a hair sample diagnostic for PSSM 2. I think it runs about $300 and it will also tell you which variant you are dealing with.

Unfortunately the EquiSeq test for PSSM 2 is not scientifically validated. It tests for several genetic markers that appear to be involved in PSSM 2. However, they do not have data on how many, or which, variants a horse needs to be confidently diagnosed with PSSM 2 and they do not have data on how many variants can be detected in healthy horses who definitely do not have PSSM 2 (or at least if they have that data, it is not published nor is it available on their website). It has the potential to be very useful, but it is not there yet.

[Squirt]

@leheath

The high selenium is weird. However, typically there is an acceptable range associated with every blood test (human and animal) and each individual will naturally fall somewhere in that range. Some will fall just outside it naturally and normally with no ill effects. It may be worth looking at the acceptable range and where your horse’s level fell in relation to it. One of the most obvious symptoms of selenium toxicity is hair loss - does your horse have any signs of hair loss either in their coat or mane or tail? Poor/crumbling hoof quality can also be a symptom of chronic selenium toxicity. Unless your horse has these symptoms, I am guessing the elevated selenium is a red herring.

His levels are 50% above the upper normal limit, which is significant but he has NO of the typical symptoms of selenium toxicity. His hair coat and hooves are excellent to the point that I get complimented on them regularly. You’re probably right that it’s a red herring.

I did only have him on overnight turnout due to limited individual turnout availability and my late cut gelding forgetting that he was a gelding.:rolleyes: I built another turnout last weekend so he’s back to being turned out 24/7 and he has been switched over to the lower NSC grain 4 days ago. I think that I’m going to let those changes go for 2 full weeks and reevaluate before adding anything else.

My first inclination is to throw everything including the kitchen sink at it and see what sticks but the rational side of me says that I need to give each change a try to see what ACTUALLY is working. He was good during my ride the night before last but we really didn’t do a whole lot. Hopefully able to ride tonight as long the weather cooperates with me.

[beowulf]

@zorion

For what it’s worth, EquiSeq now offers a hair sample diagnostic for PSSM 2. I think it runs about $300 and it will also tell you which variant you are dealing with.

A caveat about EquiSec - it is not a diagnostic. It just tells you if the gene marker is present in the horse – and it is, in a lot of breeds. That doesn’t mean the horse is affected by the disease.

There are a few FB groups that could be helpful, but I’m in a couple and there is a lot of misinformation supplied in them – and god help the poor sucker that tries to correct that misinformation. (Example - one of the more prominent PSSM groups believes that TBs are the source of all PSSM and therefore all evil and all TBs are PSSM suspects especially Northern Dancer, even though type 1 doesn’t even exist in TBs and type 2 has not been definitively diagnosed by muscle biopsy in TBs from what I have heard – there is also the misconception that EquiSec is the end all/be all to diagnosing the disease, though I do understand why people do not want to do muscle biopsy - it is a snapshot in time, and painfully invasive). Trust your vet.

OP, is your horse on any sort of grass?

I think you’re going in the right direction, switching to a PSSM friendly diet and 24/7 turnout. In my experience, the 24/7 turnout is imperative. I see a lot of PSSM types be much worse in stalled/limited TO environments.

Are you feeding any supplements? What grain were you feeding before the switch? Sel/E levels?

[Squirt]

@beowulf

A caveat about EquiSec - it is not a diagnostic. It just tells you if the gene marker is present in the horse – and it is, in a lot of breeds. That doesn’t mean the horse is affected by the disease.

There are a few FB groups that could be helpful, but I’m in a couple and there is a lot of misinformation supplied in them – and god help the poor sucker that tries to correct that misinformation. (Example - one of the more prominent PSSM groups believes that TBs are the source of all PSSM and therefore all evil and all TBs are PSSM suspects especially Northern Dancer, even though type 1 doesn’t even exist in TBs and type 2 has not been definitively diagnosed by muscle biopsy in TBs from what I have heard – there is also the misconception that EquiSec is the end all/be all to diagnosing the disease, though I do understand why people do not want to do muscle biopsy - it is a snapshot in time, and painfully invasive). Trust your vet.

OP, is your horse on any sort of grass?

I think you’re going in the right direction, switching to a PSSM friendly diet and 24/7 turnout. In my experience, the 24/7 turnout is imperative. I see a lot of PSSM types be much worse in stalled/limited TO environments.

Are you feeding any supplements? What grain were you feeding before the switch? Sel/E levels?

I am on one of the FB groups and Wooo doggy! You are right. I have not participated, just lurking.

I don’t really want to do the biopsy because I dont see how it will change our course of action, it does seem really invasive and its relatively expensive if its not going to change anything. And my current vet isn’t comfortable performing it. I do have other vets that I can turn to if I decide to go that route. And $300 to say that my horse may or may not have the markers that indicate that he may or may not have the disease or may develop it is just not a wise way for me to spend that money right now.

There is grass in his paddock but it is extremely chewed down and there are a bunch of weeds that I try to keep mowed down. I havent tried to improve my pastures because really my horses are all such easy keepers that I’m afraid that if they get any better that I will have problems pop up.

He doesn’t get any supplements. He has been on about 4#/day of Tribute Kalm Ultra for the last 5 or 6 years. This summer I top dressed 1/2#/day Essential K w/fly control that I have since stopped since fly season is winding down. I had the Tribute rep out on Tuesday to go through my feed program and to talk about product choices to make sure that I was on the right track. She took some hay samples for me and let me know about their products that might work if I find I dont like what I have settled on which is 5#/day Kalm and EZ pellet.
So I went from a 20.5% NSC grain to a 13.5%. He’s getting about 30lbs of mostly grass hay 1st/2nd cutting.

The vit E level was tested at 3.0ug/mL which is right smack in the middle of the acceptable levels and then the selenium serum levels are 240ng/mL where the reference range is 120-180. No concerns for toxicity but stop supplementing? ok. I was going to start supplementing E but I guess that allows for more uptake of selenium so I guess that’s out. Sigh.