Perennial Ryegrass Mycotoxins: Why Your Horse’s Behaviour May Suddenly Change
Podcast #70
Has your horse suddenly become anxious, spooky, reactive or unpredictable — despite being normally calm and sensible?
In this episode, Dr Nerida explores how perennial ryegrass mycotoxins can affect horse behaviour, coordination and performance. Learn about lolitrem B and ergovaline, the toxins associated with ryegrass staggers, tremors, hypersensitivity, exaggerated startle responses, heat intolerance and dramatic behavioural changes.
We also look at why some horses are affected while others are not, when perennial ryegrass pasture and hay pose the greatest risk, how quickly horses may improve once exposure stops, and whether mycotoxin binders can actually help.
If your horse seems to have had a sudden “personality transplant”, their pasture or hay may be worth a closer look and this episode is definitely worth a listen!
Testing pasture or hay for perennial ryegrass toxins
Australia: Southern Scientific Services, Hamilton VIC – pasture toxin testing including lolitrem B and ergovaline. Phone 0408 363 061. Contact the laboratory before collecting/sending samples for current sampling instructions.
USA: Oregon State University Endophyte Service Laboratory – quantitative testing for lolitrem B and ergovaline in pasture, hay and feed. https://emt.oregonstate.edu/endophyte-lab
📲 For help balancing your horse's diet, download the MyHappy.Horse App https://apps.apple.com/au/app/myhappy-horse/id6633422324
💖 If you found this episode helpful, please follow the Happy Horse Nutrition Podcast and share it with a horse owning friend who is struggling with their horse's behaviour.
🌟 And we'd love you to leave us a rating and review, it helps us help more horse owners to find practical, science-based nutrition advice.
-
70. Perennial Ryegrass Mycotoxins: Why Your Horse’s Behaviour May Suddenly Change
[Nerida McGilchrist] 14:36:19
Hello and welcome back to the Happy Horse Nutrition podcast. I'm Doctor Nerida, PhD, equine nutritionist, lover and baker of good sourdough bread, and someone who is a bit more than mildly freaked out by the stories from centuries ago about what would happen to people.
[Nerida McGilchrist] 14:36:36
when they ate rye bread contaminated with ergot alkaloid mycotoxins. So, if you've ever come across these stories, they're pretty horrific. There was a condition called St Anthony's Fire. It was called St Anthony's Fire, apparently, because a lot of.
[Nerida McGilchrist] 14:36:51
people were treated in a St. Anthony's hospital. But what would happen is that rye grain, which was commonly used in breads back in the 1600s, and it was probably happened in other centuries as well.
[Nerida McGilchrist] 14:37:06
Um, but the reading I've done in this area, mostly out of curiosity, is from the 1600s, but people would eat bread that had been contaminated with a claviceps fungi.
[Nerida McGilchrist] 14:37:21
And then that fungi would produce an ergot alkaloid mycotoxin. And that mycotoxin in the human body would cause severe vasoconstriction. So it would stop blood flowing essentially to the extremities.
[Nerida McGilchrist] 14:37:37
And the people affected would experience intense burning in their hands and feet, and they would be cold and have a loss of sensation also in their hands and feet. And eventually they would experience tissue death and gangrene, and then they would die.
[Nerida McGilchrist] 14:37:54
But there was also a
[Nerida McGilchrist] 14:37:58
I don't know what the right word is, neurological part of it, where they would also experience crawling sensations all over their skin, and delirium, paranoia, hallucinations, and just to top it all off, because you needed more to go along with all of that.
[Nerida McGilchrist] 14:38:16
severe diarrhea and abdominal pain. So it sounds horrific. I think I think there might have been a case of this ergot poisoning in maybe France. It's been a while since I've read lots of literature in in this space.
[Nerida McGilchrist] 14:38:32
Um, recently, but we virtually don't see this anymore because we're aware of the problems with this ergot alkaloid, and there's much better quality controls around what grains are used in bread these days.
[Nerida McGilchrist] 14:38:46
one really interesting… I promise I'm getting to the point here with horse nutrition, but actually, I'll tell you what the point is now. I… this… in this podcast, we're going to talk about mycotoxins from ryegrass, and I'm telling you about St. Anthony's Fire, just so that you can… because horses can't speak to us.
[Nerida McGilchrist] 14:39:05
And we don't actually know what their physical experience is, but as we go through this podcast, you'll realize that maybe some of their physical experience is something similar to what all of these poor people back in the 1600s were experiencing with this St. Anthony's fire.
[Nerida McGilchrist] 14:39:21
They can't tell us that. And we can only we can only read their symptoms through their behaviour. So there is lots of mycotoxins that can affect our horses and and some of them are ergot.
[Nerida McGilchrist] 14:39:37
alkaloids, which are the same class of mycotoxin that cause this, and it inspire. I just wanted to add quickly, still on the human side, there is a school of thinking that maybe the Salem witch hunt, which happened in 1692.
[Nerida McGilchrist] 14:39:54
was, um…
[Nerida McGilchrist] 14:39:55
had something to do with rye ergot poisoning in humans, that the symptoms the supposed witches were displaying were possibly due to ergot alkaloid mycotoxin poisoning. But there's also papers contradicting that, so I don't know whether that's the case.
[Nerida McGilchrist] 14:40:16
you can kind of imagine that when people were behaving the way that they were behaving, if they were affected by these mycotoxins, they probably did seem like they were… I don't want to say witches.
[Nerida McGilchrist] 14:40:30
I think there's lots of good witches in the world. Um, but, you know, they seemed like they were possessed in some way if they didn't understand, which they didn't at the time, didn't understand the science behind mycotoxin poisoning.
[Nerida McGilchrist] 14:40:43
So the reason I'm doing this podcast today.
[Nerida McGilchrist] 14:40:47
is because I had a lovely call from one of our beautiful My Happy Horse app members, Abby, and she was talking to me about a little paint mare of hers, and there was a couple of things going on for her. So she'd had diarrhoea, and she said she was also.
[Nerida McGilchrist] 14:41:05
Really nervous, reactive to things. And she said, ah, she was sold to me, you know, as I've been there, done that really quiet horse. And this horse had moved from Sydney down to the southern parts of New South Wales on the eastern side of Australia, if anyone is listening to this outside of Australia.
[Nerida McGilchrist] 14:41:25
And the forages that this horse now has access to are very…
[Nerida McGilchrist] 14:41:30
very, very different to the forages that she would have had access to in Sydney. Anyway, this paint had to go to a vet clinic to have a, um, cancer removed off her nose, and Abby said when she came home.
[Nerida McGilchrist] 14:41:45
Her manure was better, and they'd added some lucid chaff in, and I said, well, actually, that's not surprising, because often when we do put a different source of forage or fibre into a horse's diet that's had persistent diarrhoea, it often will improve.
[Nerida McGilchrist] 14:42:02
But I said to her, and I don't even know why I said it, I said to her, but it could also be coincidence. It could be that you've put that lucerne in, and it looks like it's been what has made the change.
[Nerida McGilchrist] 14:42:13
but it could be something else, and that the timing was just purely coincidental. And then, as we kept chatting, and she was telling me about this horse's behavioural issues, I started thinking, maybe this horse is affected by ryegrass microtoxins. And…
[Nerida McGilchrist] 14:42:27
it was… it was such a… I love these conversations, because, you know, everything just keeps unfolding.
[Nerida McGilchrist] 14:42:35
And I said to Abby, how was her behaviour after she'd been at the vet clinic? Because she'd gone into the vet clinic, and then she was off her… off her pasture, which does have ryegrass in it.
[Nerida McGilchrist] 14:42:45
And he said, you know, funny story, when she went to load her on the float, she was late for work and she said, you know, the horses pick up on our energy, but she was hard to load on the float and she was really anxious and, you know, bouncing off the energy as well.
[Nerida McGilchrist] 14:43:02
And when she went to pick her up, she was thinking, oh, I'm gonna need help to load her, and she said she was just so much calmer. I went, well, that makes sense, because she'd been off ryegrass for a few days, and it does only take a few days for a lot of their symptoms to settle down, so a lot of the behavioural symptoms to settle down.
[Nerida McGilchrist] 14:43:21
And when she went to pick her up, she was more like what it sounds like she should have been from the description from her previous owners. And Abi said to me, I've never heard of this. And it made me realise that there are lots of people still that don't and understandably that don't realise.
[Nerida McGilchrist] 14:43:41
that pastures, particularly at this time of year in the Southern Hemisphere, and anyone who's got ryegrass, perennial ryegrass in their pastures.
[Nerida McGilchrist] 14:43:51
These… these grasses can cause pretty dramatic behavioural changes, but if you don't realize that it can be your pasture, you'll go down so many rabbit burrows trying to figure out what is going on with your horse and its behaviour, when really.
[Nerida McGilchrist] 14:44:07
all it is is the mycotoxin coming from the ryegrass. So we'll just back up a little bit. Perennial ryegrass isn't always mycotoxin-affected, but a lot of perennial ryegrass has got a fungi, an endophyte fungi living with it, so it's a fungi that lives with and in the grass.
[Nerida McGilchrist] 14:44:27
And that fungi's job is to look after the grass, essentially. So the fungi produces these mycotoxins.
[Nerida McGilchrist] 14:44:35
And those mycotoxins give the perennial ryegrass some insect resistance, and they also improve the pasture persistence. So, you know, they cope with dry conditions and maybe a little bit more heat and, you know, all the things that stress pasture.
[Nerida McGilchrist] 14:44:50
these endophyte fungis help the pasture to cope with the environment that it has found itself in. So from the plant's perspective, they're really cool. They help the plant out a lot. But from our animal's perspective, what happens is that these fungis will produce mycotoxins, and in perennial ryegrass.
[Nerida McGilchrist] 14:45:09
there are two major mycotoxins. So there's one called Lolotrim B, and the other is called Ergovaline. They're not the only two, but they are definitely the two most common in perennial ryegrass.
[Nerida McGilchrist] 14:45:22
So the Lolotrin B.
[Nerida McGilchrist] 14:45:25
is a mycotoxin that is well known to cause what we call perennial ryegrass staggers. And if you've ever seen a horse with perennial ryegrass staggers, it's quite scary watching them trying to move, because they literally lose their coordination, and they try to move, but.
[Nerida McGilchrist] 14:45:42
They're really, really uncoordinated. It looks like they've been out at the bar for way, way too long with their mates. But, and the somewhat confusing thing is that some horses will get really severely affected by it and other horses not so much. So it's sometimes hard to realize that things that you're seeing in horses at pasture are due to the pasture, because not all horses are affected.
[Nerida McGilchrist] 14:46:05
equally by the pastures. But they… these lower trims, uh, if you read up on them, you will read things like they will cause an exaggerated startle response, so your horses will, um, get, you know, something that… that wouldn't normally frighten them, like maybe a plastic bag being pulled out of.
[Nerida McGilchrist] 14:46:25
out of a bucket or something like that, that wouldn't normally scare them. They'll get much more of a fright when you do that, if they're affected by the mycotoxin. Just behaviour that is described as unusually spooky and reactive.
[Nerida McGilchrist] 14:46:40
And they'll be hypersensitive to sound and movement. And it's interesting, if you talk to dairy farmers about horses… sorry, about… not too many dairy farmers that milk horses. If you talk to dairy farmers about their cattle, they will tell you that they are more sensitive to sound.
[Nerida McGilchrist] 14:47:00
So if you drop something or make a bang in the, in the, um, dairy, they'll, they'll startle easier. Uh, really sensitive to flies, so where they would normally just stand there calmly, if there's flies landing on them, they'll be kicking and carrying on, and when you've got milking cups on dairy cows.
[Nerida McGilchrist] 14:47:15
you don't want them to be doing that, you want them to
[Nerida McGilchrist] 14:47:18
You're standing there nice and calm. You also don't want them to be kicking and they will kick more when, you know, if you're touching them on the on the back legs as you're putting as you're putting cups on. This is taking me back to my rural science work experience days when I did some time in a dairy. I loved it. The dairy cows are so they're so beautiful, but you really don't want them kicking at you when you're sort of down, you know, their legs are at your head height.
[Nerida McGilchrist] 14:47:41
You don't want them kicking at you, but that's what they do when they're affected by these ryegrass mycotoxins. Um, in horses, we also find, um…
[Nerida McGilchrist] 14:47:52
That they will become erratic and unpredictable. So, you know, normally you get to know if you've got a horse and you've had a horse for quite a long time, we do get to know their behaviours, you know, the things that they like and the things that they don't like and the things that they're sometimes challenged by and, you know, we can work around all of those things for our horses, but when they're affected by this mycotoxin.
[Nerida McGilchrist] 14:48:14
their behaviour suddenly becomes unpredictable, and… and it is dangerous. So, if you're listening to this and going, I wonder if this is what's going on for my horse at the moment, um, they are… they are dangerous, or far more dangerous, when… when they're affected by these mycotoxins, because they're not.
[Nerida McGilchrist] 14:48:32
thinking and able to process information the way that they would normally think and process. So the Lolotrim B as well, as I said, it affects their coordination. So sometimes you'll see them standing like with a wide stance.
[Nerida McGilchrist] 14:48:49
trying to, trying to, um, a little bit like someone who's been at the bar with their mates for too long, but trying to maintain their balance. Um, they might stumble when they wouldn't normally, they might toe drag when they wouldn't normally, and, um, you might notice that they have difficulty turning.
[Nerida McGilchrist] 14:49:05
Where they would normally, you know, be able to turn in a really coordinated way, if they're affected by these mycotoxins, they can have difficulty turning. And when it's really bad, they actually can't stand up. And it can be fatal, so they can be affected so badly that they won't be able to stand, and then if you don't help them and try to fix it.
[Nerida McGilchrist] 14:49:24
and give them proper veterinary support, it can be fatal. I thankfully don't know of any cases that have ended in fatality, but I have certainly worked with horses that have gotten to the point where.
[Nerida McGilchrist] 14:49:40
you watch them try to walk, and they just can't. Like, they're so totally uncoordinated that every time they try to move, they either do fall over, or they nearly fall over. So…
[Nerida McGilchrist] 14:49:52
Um, there's… there's lots of… there's lots of manifestations, and in fact, one of the… one of the really early signs that you'll see in horses that are affected by the… the Lolotrim mycotoxin is that the…
[Nerida McGilchrist] 14:50:06
the corners of their eyes will start to shake and quiver, and then their ears will also start to quiver, and you might just see some… just some little muscle quivers that wouldn't normally be there for your horse. So, if…
[Nerida McGilchrist] 14:50:22
if you've got perennial ryegrass, and you suspect that maybe your horse's perennial ryegrass affected, just look for… it doesn't… it's not always the big symptoms, it's not always the staggering, or the, you know, incoordination, or the dramatic behavioural changes. Sometimes it can just be.
[Nerida McGilchrist] 14:50:42
that the corners of their eyes or their… or their ears are twitching, or you'll just see little… little muscle twitches, um, somewhere else in their body. So, the reason…
[Nerida McGilchrist] 14:50:54
the… that mycotoxin, the Lolotrim-B, causes all of these symptoms is because it is… are you ready? This is a big mouthful of words coming… a large conductance calcium-activated potassium channel inhibitor. So, it… it messes up.
[Nerida McGilchrist] 14:51:09
the contract and relax.
[Nerida McGilchrist] 14:51:14
processes in a horse's muscles. I don't know a lot about that, so if I've gotten that completely wrong, someone please correct me on it, but it changes the way muscles function, and then they and then horses lose.
[Nerida McGilchrist] 14:51:29
coordination. But the other thing, and I think the more…
[Nerida McGilchrist] 14:51:36
important part of perennial ryegrass that… that we need to be aware of as horse owners is the fact that they would cause these behavioural changes outside of staggering and losing coordination. So what… and I see this…
[Nerida McGilchrist] 14:51:50
Probably 90% of the time I might see the actual, you know, muscle tremors and and loss of coordination, maybe 10% of the time. Definitely the that the behavioral changes and the anxiety and the spookiness and the.
[Nerida McGilchrist] 14:52:07
other, uh, like, herd-bound behaviour and being more prone to kicking and… and all the things that horses affected by ryegrass mycotoxin can do, um, that is what I see the most. That's what… what Abby was describing to me with her… with her little paint mare.
[Nerida McGilchrist] 14:52:25
So… and I think a reason… the reason a lot of those…
[Nerida McGilchrist] 14:52:30
changes happen is due to the second mycotoxin that is in the perennial ryegrass, so the ergovaline, which is the one that is related to the mycotoxin from the rye ergot alkaloid that was causing the St Anthony's fire in humans back in the 1600s.
[Nerida McGilchrist] 14:52:47
So, ergovaline, here's a fun fact for you, is chemically related to LSD.
[Nerida McGilchrist] 14:52:53
as in the hallucinogenic drug LSD. It's not the same as, um, but it is chemically related to that. And, um, when you read that list of… when you read that list of, um, symptoms that the… that the humans had with the…
[Nerida McGilchrist] 14:53:11
Um, hallucinations and, um…
[Nerida McGilchrist] 14:53:15
paranoia and delirium, it kind of starts to make sense, and it's not to say, and again, you know, we don't know what our horse's experience is, but I sometimes say to people with horses that are severely affected by perennial ryegrass mycotoxins.
[Nerida McGilchrist] 14:53:30
For all we know, they are actually seeing goblins hiding behind every tree. We don't know what their experience is, but they certainly can dramatically change their behaviour. So, I… I remember…
[Nerida McGilchrist] 14:53:45
I must have been, I was probably about Tamaya's age, my daughter's age, 16 or 17 years old, and I'd headed off to big agricultural field days, a lot of you will know it, called AGQIP in Gunnedah, that's held in mid-August.
[Nerida McGilchrist] 14:54:01
every year.
[Nerida McGilchrist] 14:54:03
And I remember as a kid, so dramatic as a teenager, but, um, and I wasn't a very dramatic teenager, but I remember thinking this was the worst day of my life, um, at this point in time, because I'd been to Agrip all day. I came home to realize that Coco, my beautiful mare, had actually jumped.
[Nerida McGilchrist] 14:54:21
out of her paddock and had completely flattened a gate and injured herself in the process. And then she had, like, bolted down the road, um, and… and jumped over.
[Nerida McGilchrist] 14:54:33
Two cattle grids, which she would never normally have jumped over, and then she ended up maybe…
[Nerida McGilchrist] 14:54:39
3 or 4 kilometers, maybe even more, down the road, and a neighbor saw her, and everyone knew my horse, thankfully, so a neighbor saw her and knew exactly who she was. And they caught her and took her back and put her in the paddock, and she did it again!
[Nerida McGilchrist] 14:54:52
And it was so… such uncharacteristic behaviour for her. And, you know, I think about that now, and I think, it was August, and this is the time of year that this behaviour will start to show up.
[Nerida McGilchrist] 14:55:05
And it was… she was also in a paddock that I know, without a doubt, had perennial ryegrass in it. So I always wonder, you know, was she…
[Nerida McGilchrist] 14:55:15
ryegrass affected, and… and that was how it was coming out in her behaviour. And it…
[Nerida McGilchrist] 14:55:22
I… I think then about a big horse in South Australia, and again, this was… this was years ago, but not quite as long ago, was… as the cocoa incident. Oh, sorry, I need to finish the story about the worst day ever at Aquip, so… so my horse had jumped.
[Nerida McGilchrist] 14:55:38
out, uh, and run away, essentially. And then, when I eventually got back to the house, I'd realized that my pet lamb, Lucy, had also escaped for the day, and she'd made it all the way up the front steps and had eaten every single one of my mother's pot plants.
[Nerida McGilchrist] 14:55:58
And my mum was not happy about that, so I just… I just had this wild day with… with my animals, but anyway, the pot plants, um, some of them grew back, and we moved my horse into a different pasture, and she never did it again, but I think I probably never ever put her in that.
[Nerida McGilchrist] 14:56:12
paddock again either. Um, but the change… the behavioural changes are dramatic. So, professionally, as an equine nutritionist, I've… I've since worked with… so I had no idea what was going on with cocoa back then, but… but I've since worked with horses who have been severely affected.
[Nerida McGilchrist] 14:56:30
And the one that stands out in my mind the most is a big show jumper in South Australia who was imported from the USA. And, um, when the owners got in contact with me, it was via.
[Nerida McGilchrist] 14:56:46
Prides, when I was doing a lot of work with Prides back then, and they said, we cannot keep this horse in a paddock. It just keeps jumping. It jumps out of every paddock we put it in. I think it was probably even jumping out of its stables. It's a showjumper, so it's very hard to.
[Nerida McGilchrist] 14:57:02
to lock something in that is is trained to jump. And that's that's its occupation. And eventually we figured out that it was the ryegrass pasture which there's lots and lots of ryegrass pastures in South Australia at various times of the year.
[Nerida McGilchrist] 14:57:18
And once we managed to keep that horse confined for long enough to get the ryegrass out of its system, completely went back to normal.
[Nerida McGilchrist] 14:57:26
So… and I've always wondered after that horse that, you know, he… he was from the USA, so he'd never actually been exposed to these particular grasses and this particular climate. It always made me wonder that where the horses who…
[Nerida McGilchrist] 14:57:41
have not experienced the mycotoxin when they're young, whether they're more affected. Because one of the confusing things is, and this is the case for Abby in the paint, is that not all horses are affected in this way with their behaviour.
[Nerida McGilchrist] 14:57:58
So the little paint horse is really affected.
[Nerida McGilchrist] 14:58:02
And these other two mares, not affected at all. So it's really… it's hard to stop and go, this is… this is the pasture, because our assumption often is that, well, if it was the pasture, then all of the horses would be affected. But do keep in mind that.
[Nerida McGilchrist] 14:58:17
It can be the pasture, and not all horses are affected. And in fact, some horses will be really severely affected behaviour-wise, and other horses will not be affected at all. So it really is important to keep that in mind.
[Nerida McGilchrist] 14:58:33
Um, and then another… another case that stands out in my mind was at Equitana, and I really don't know why I remember this one so clearly, but we were at Equitana, and, you know, people were coming up to us in, you know, pretty rapid succession, asking about their horses' diets.
[Nerida McGilchrist] 14:58:51
And I remember this guy, and he was asking for a cool feed and, you know, something that could sort of get on top of his horse's behaviour. And the more we spoke, the more I started to go, there's something just not quite right here. And I said to him, does she happen, this mare, does she happen to change her behaviour like this at this time of year?
[Nerida McGilchrist] 14:59:11
each year. And and it's not. It wasn't a great question, because it's not necessarily going to happen every year, because the the fungi that lives with the grass doesn't necessarily produce mycotoxin at the same level every year.
[Nerida McGilchrist] 14:59:27
and I'll explain as well that it kind of depends also what stage the pasture is in as to whether the mycotoxin is going to be present. Anyway, I asked him, does she change? And he said, actually, she does this time of year. Her behavior changes. And then we talked about his pasture, and there was perennial ryegrass in the pasture. It has got a very distinct seed head. So if you're wondering whether.
[Nerida McGilchrist] 14:59:49
you have got perennial ryegrass, just Google it, perennial ryegrass seed head, and look at images, and you'll see the perennial ryegrass seed head. It is very distinctive, and you will know, you'll recognise it, because I'm sure you will have seen it if you have got perennial ryegrass in your pasture.
[Nerida McGilchrist] 15:00:06
So, there's been… there's been lots of horses over the years, um, that… that I've… I've come across, but they're just a few that sort of really, really stand out in my mind.
[Nerida McGilchrist] 15:00:17
And it's interesting, when we look at this ergovaline mycotoxin, the second mycotoxin that can be in perennial ryegrass, and the one that is chemically related to LSD, it does do similar things to the mycotoxin that causes the St. Anthony's fire, so it will cause vasoconstriction, so it.
[Nerida McGilchrist] 15:00:39
um, reduces the flow of blood to the extremities, and in fact, in cattle, I'm pretty sure one of the symptoms when they're… when they're really bad, um, is issues in their hooves, and also their ears. Like, their ears get… I guess it's something like gangrene, but, like, they…
[Nerida McGilchrist] 15:00:54
the extremities of their ears die, and they lose their ears. In horses, you will get impaired heat dissipation, so they can't offload heat as well as they otherwise would be, and then they can blow.
[Nerida McGilchrist] 15:01:09
harder after work. So, you know, this is something in racehorses, particularly if you happen to get in, you know, ryegrass hay, and then all of a sudden your horses are blowing really hard after work is probably a really good idea to get the get the hay tested for mycotoxin contamination.
[Nerida McGilchrist] 15:01:27
Um, we will see reproductive issues, um, and it's interesting, like, you read papers in ruminants about the perennial ryegrass mycotoxin poisoning, and, um, realize that they'll do things, like, one paper I read, there was sheep.
[Nerida McGilchrist] 15:01:45
who were hot because they had impaired heat dissipation, but they also weren't seeking out shade. They were all huddled together, like jammed up against a fence out in full sun, even though they were really hot. So they sort of like they lose their ability to process information and to behave in a normal way.
[Nerida McGilchrist] 15:02:03
if you've had a horse that's been affected by ryegrass mycotoxin, you'll know what I mean, because they… it's like they, um… it's like my kids when they have sulfites.
[Nerida McGilchrist] 15:02:16
if you've realized in kids, certainly for my kids, it's true. If my kids eat anything with sulfites in it, I literally say to them, I'm not your mother tomorrow, because you're not going to be able to think properly. And certainly when they were young, you know, they couldn't…
[Nerida McGilchrist] 15:02:34
process information. I remember really distinctly, she'll kill me for saying this on the podcast, but Tamaya, in our swimming pool that we had when she was small, and she'd gone up to the side of the pool, and then she'd just brushed against one of the water intake.
[Nerida McGilchrist] 15:02:53
um, little filters, where the… where the pool sucks the water in to… to filter it, and… or blows it back out, I can't remember. It was something sort of poking out off the… off the side of the pool wall, and she absolutely freaked out, and was clinging…
[Nerida McGilchrist] 15:03:08
clinging onto the side, because she thought there was something in the pool that… that had touched her. And, um… and she was inconsolable, like, and I couldn't say to her, sweetie, it was just the… it was just the… the vent thing, and there's nothing in the pool.
[Nerida McGilchrist] 15:03:24
And it took me ages, like, ages to work out with her that her behaviour that I was seeing was from the sulphites, which destroy vitamin B1, and this is, like, a massive rabbit burrow now, but you can go and, um, read up about the really devastating effects of sulphites in dog food.
[Nerida McGilchrist] 15:03:43
Um, because it does destroy vitamin B1, and, and, um, back in the day, and I don't think it's allowed anymore, but, um, butchers were putting sulfites in mints, dog mints, to keep it nice and bright red, and stop it from oxidizing and going brown, and…
[Nerida McGilchrist] 15:03:58
dogs were getting so vitamin B1 deficient that they were actually dying. Um, so you're not allowed to put that in mints anymore, but it's in sausages everywhere that we feed to our kids. And then, for my kids at least, if they ate those foods, they… they just… they couldn't process information. So, all that to say, long roundabout way.
[Nerida McGilchrist] 15:04:18
Um, you know, the sheep jamming themselves up against the fence and not going to seek shade. Some of you may say that's just sheep being sheep, but no, uh, if they're not… if they were not affected by the mycotoxin, they… they would have been able to seek out shade normally.
[Nerida McGilchrist] 15:04:35
Um, and these horses do… they just lose their ability, and this is why you have to be really careful with them. If you think you've got a horse with… with mycotoxin, um, poisoning, do be really careful when you're handling them, because they… you know, a horse that would normally be very respectful and not jump on top of you if it gets.
[Nerida McGilchrist] 15:04:53
fright can just jump on top of you because they're not processing information properly. So do be really, really careful when you are handling them. Please don't ride them as well. They're definitely, definitely not safe to ride. I saw it described years ago as it being the equivalent of hopping into a car with a drunk person.
[Nerida McGilchrist] 15:05:12
Which you would never do if you're in the right frame of mind. So, um, yeah, just be really careful and don't ride these horses that, um, are ryegrass affected. So, there are certain times of the year and also certain stages of.
[Nerida McGilchrist] 15:05:28
Grass growth where they are more dangerous from a mycotoxin perspective, so the endophyte fungi tends to live.
[Nerida McGilchrist] 15:05:38
In the lower part of the leaf sheath, so the bottom part of the leaf, and also in the base of the plant, so the part of the plant, essentially, that is closest to the ground.
[Nerida McGilchrist] 15:05:50
Or, it's in the seeds. So, perennial ryegrass that is either overgrazed.
[Nerida McGilchrist] 15:05:58
and eaten really close to the ground, or has been let go rank and have lots of seed heads and, you know, go to seed. They're the two most dangerous types of perennial ryegrass pasture for a horse to graze.
[Nerida McGilchrist] 15:06:13
Now, to add to the mystery, I guess I'm going to call it, not all perennial ryegrasses have this endophyte fungi, and even if they do have the endophyte fungi, it's not going to always be producing mycotoxins at the same concentration.
[Nerida McGilchrist] 15:06:28
You might find that, you know, your horses are normally fine, but they're one season for whatever reason, and it might be that your pastures are more eaten down than normal, or they've been allowed to go to seed more than normal, but for some reason.
[Nerida McGilchrist] 15:06:47
the mycotoxin concentration in your pastures at different times of the year, and also from year to year will vary. So you might find that sometimes your horses are fine, and other times, all of a sudden, you'll have horses that are affected.
[Nerida McGilchrist] 15:07:00
So, um, the signs of… of mycotoxin poisoning, one paper suggests that they will appear in 4 to 9 days.
[Nerida McGilchrist] 15:07:11
And the problem is, though, it's not necessarily going to be 4 to 9 days after they've gone onto that pasture, because maybe when you put them on the pasture, the pasture was at a lovely, you know, leafy vegetative stage, and it wasn't eaten down, it didn't have any seed heads, and so it was quite safe for them to graze.
[Nerida McGilchrist] 15:07:27
But then you might find that as the season goes on, and the seed heads start to appear, or the horses either pass it down, they might get, um, affected. Now, it is important to remember, too, that hay made from perennial ryegrass can definitely have these mycotoxins in it, and that's probably where this timeline, four to nine days, is more relevant.
[Nerida McGilchrist] 15:07:46
if you introduce a hay into your horse's diet, and… and all of a sudden, you know, the horse is behaving in a way that you… you don't expect, um, suspect that it is the hay, and… and take that hay out. And in fact, I've just reminded myself too, there was another… another, um.
[Nerida McGilchrist] 15:08:06
my happy horse member, and I'm just gonna go and look up their email. The horse's name was Luke. I'm terrible. I can remember the horse's names. And… and not the… not the people's names. Hang on. I'm… I'm trying to find it in my emails as we speak.
[Nerida McGilchrist] 15:08:32
Ah, it was Rebecca, that's right, and her horse was Luke. So, Luke was another interesting one, so… and he… he really showed the symptom of being excessively herd-bound, and this herd-bound behaviour is one that I find is quite common, so I do see it a lot with horses that are.
[Nerida McGilchrist] 15:08:49
perennial ryegrass affected, but he was really, really bound to his young owner, and if she, you know, if they were out at a show or something, and she headed off and left him, he would really freak out, because she wasn't quite close to him, which is really sweet that he was so bonded to his human that that was his safe place, but.
[Nerida McGilchrist] 15:09:11
also not, um, you know, they didn't want him to be like that. They wanted him to be calm and to be happy, um, and not get so anxious when, um, his young little rider was close by.
[Nerida McGilchrist] 15:09:23
Anyway, I was I was chatting with Rebecca and it came like they were feeding this beautiful mix of hays, like all these different types of hays. And one of them was ryegrass hay. And I went, I said to her, I wonder if it might be the ryegrass hay.
[Nerida McGilchrist] 15:09:40
Anyway, I… I suggested they take the ryegrass hay out and… and leave him… leave it… leave him off it. And I sent them an email the other day saying, just checking in to see how Luke's going. Got an email back saying he's going so well. I do think the ryegrass has reduced his agitation and he's more relaxed and not as twitchy.
[Nerida McGilchrist] 15:09:59
And same with our mayor, who's also off it. Um, and then they sent a photo of Luke lying down in his rug with his… with his owner, just fast asleep on the ground there with his… such a… it's such a cool photo. So, it's, um…
[Nerida McGilchrist] 15:10:14
it is quite common, uh, another horse that… that also comes to mind, you know, long time, like, um, just anxious horse, and was getting a mixed grassy hay that, you know, may or may not have had ryegrass, and said to Kate, you know, maybe just take.
[Nerida McGilchrist] 15:10:32
take that hay out that he's been… he'd been on it for years, but he'd also been this anxious, um, anxious horse for years as well, um, take him off it. And it… it also did seem to make a difference. So, if you… if you do have, uh, a horse that's on ryegrass hay, and they are more anxious than you would like them to be.
[Nerida McGilchrist] 15:10:53
It's really worth just taking them off it for a while. And certainly also if you have a horse out on pasture and they have got any of that long list of symptoms. And the other the other one, which I can't remember now whether I've mentioned it, is gastrointestinal symptoms. So they can get diarrhoea.
[Nerida McGilchrist] 15:11:10
Uh, and… and maybe colic, it's not something that… that comes to mind, um, in my experience, but… but maybe, um, that… that could be a symptom as well, but certainly diarrhoea. And… and that was, you know, Abby's paint, that was one of the… one of the main things she wanted to use my happy horse to try and sort out.
[Nerida McGilchrist] 15:11:29
with her was this, um, diarrhea issue, but… which, when she went to the vet clinic and was off her pasture for a few days, that cleared up. So it was probably the mycotoxin causing that. So if you… if you do have horses on pasture or hay that…
[Nerida McGilchrist] 15:11:45
either have definitely got ryegrass, or you suspect maybe have got ryegrass. Take them off it for a few days.
[Nerida McGilchrist] 15:11:52
There was one paper, it was a Belgian study, uh, and they, they deliberately put, um, horses, I think, I read lots, but, um, had put horses on the ryegrass, um, and mycotoxin-infected hay, uh, and.
[Nerida McGilchrist] 15:12:07
and then when they removed the hay, it could also have been horses that were just naturally affected, and it was written up as a case study. Don't quote me on… on either of those things. I'm not… because I can't remember which one it was, but…
[Nerida McGilchrist] 15:12:19
Point being, 3 days after they took those horses off hay, their symptoms improved. So, if you suspect that maybe something with ryegrass is going on for your horses, just take them off whatever it is that has got the ryegrass in it, and just see if their behaviour changes, because it does happen.
[Nerida McGilchrist] 15:12:36
Really, really quickly.
[Nerida McGilchrist] 15:12:38
So managing it then becomes tricky. If it's hay, then there's plenty of other options for hay. So if you're using ryegrass hay and your horse is affected by mycotoxins, then definitely don't use that batch of ryegrass hay.
[Nerida McGilchrist] 15:12:53
The tricky thing is, not all ryegrass hays are going to be a problem.
[Nerida McGilchrist] 15:12:59
You can have these mycotoxins tested, and I will find, um…
[Nerida McGilchrist] 15:13:07
I'll try and find some labs that you can actually send hay off to be tested, so if you, you know, if you're questioning whether your hay is actually safe, you can send it off to have it tested. I'll put that in the show notes for you. Um, for pasture.
[Nerida McGilchrist] 15:13:22
the first thing to do is just try and manage the pasture so that ryegrass pastures never get really eaten down, and if you know that your pastures are a problem, try not to let them go to seed as well. Try to graze them off and eat them before they… before they…
[Nerida McGilchrist] 15:13:37
get a chance to go to seed. Um, I'm pretty lucky where I live. I've got lots of perennial ryegrass in my pastures, but I don't have any horses that seem to be affected by it either. Breeze, maybe. I always wonder with her, because her… at certain times of the year, her eyes twitch and her nose twitches, and when she's really bad, her ears twitch.
[Nerida McGilchrist] 15:13:57
But I also don't know whether that's just because she's seriously ancient, like she's nearly 40 and she's just got the old lady twitches. But we've got massive amounts of ryegrass at the moment. It's all very still leafy and green and happily growing at the moment. But I will keep a close eye on her to see whether when the seed heads start appearing.
[Nerida McGilchrist] 15:14:21
Whether that's when she starts to get more of the quivery shakes. But, you know, she gets them sort of in at other times of the year as well. And I've never been able to to figure out whether it is actually something related to what she's eating or doing and or whether it's just something that that happens with her because of her age.
[Nerida McGilchrist] 15:14:44
And yeah, if it really comes down to it and you do have a horse that's badly affected and you've got ryegrass in your pasture, then it may be a case to keep you safe and to keep your horse safe that you just have to keep them off pasture for the risky times of year until the perennial ryegrass comes and then leaves again and then it is safe to put your horse back out on pasture.
[Nerida McGilchrist] 15:15:09
And the last little thing I want to cover before I wrap this one up is whether mycotoxin binders help. So there's lots and lots of mycotoxin binders sold on the market, and I know lots are used in an attempt to try and help horses that.
[Nerida McGilchrist] 15:15:25
Are perennial ryegrass mycotoxin affected? The first thing to be aware of is that not all mycotoxin binders are going to have any kind of impact on the perennial ryegrass.
[Nerida McGilchrist] 15:15:40
Mycotoxins, so there's some mycotoxin binders that essentially work like a magnet, and if you put them close to a mycotoxin like aflatoxin, which has got a charge, the mycotoxin binder has got the opposing charge, and it will attract the aflatoxin mycotoxin to it and hang on to it and drag it out of the horse's gastrointestinal tract.
[Nerida McGilchrist] 15:16:04
But they're… and they work beautifully, those mycotoxin binders, for the charged mycotoxins, but the Lolotrim B and the Ergovaline that are in perennial ryegrass are not charged mycotoxins, so you can't…
[Nerida McGilchrist] 15:16:18
Pick them up like a magnet the way you can with something like aflatoxin, so you need a mycotoxin binder that is actually going to deactivate these mycotoxins in some way. So there are some mycotoxins that have got some effect.
[Nerida McGilchrist] 15:16:38
on the toxins in perennial ryegrass. The biggest problem for horses and feeding toxin binders to counteract toxins in hay or pasture is we don't have a rumen. Skittles saying hello, everyone. Sorry if you can hear her.
[Nerida McGilchrist] 15:16:54
We don't have a rumen to allow the mixing of the mycotoxin binder with the forage, so we can feed the mycotoxin binder in, say, the horse's feed, but whether or not it then comes in contact with the mycotoxin.
[Nerida McGilchrist] 15:17:11
is a whole other question.
[Nerida McGilchrist] 15:17:13
And often, it probably is not going to come into enough contact with the mycotoxin for a horse that's grazing perennial ryegrass pastures to be able to counteract that mycotoxin enough to completely reduce the effect of that mycotoxin on the horse. So, it'll be a case of.
[Nerida McGilchrist] 15:17:32
Try it and see. If it works, happy days. If it doesn't work, then you will have to take the horse off the pasture, or remove the ryegrass hay from the diet, and provide them with alternate forage.
Okay, sorry, I just had a little short break there. Skittles was barking because my mum and dad had just arrived. So coming back to this, I guess the main reason I wanted to do this podcast is because I consistently come across these horses with behavioural problems.
[Nerida McGilchrist] 16:12:24
And owners who are just really struggling to try and figure out what on earth is going on with this horse, you know, that they just seem to have had a personality transplant and are not the horse.
[Nerida McGilchrist] 16:12:36
they either knew them to be, or, you know, in Abby's case, they're not the horse that you thought you purchased. It told you you're purchasing something that is just absolutely bomb-proof and steady and beautiful, and then you get this anxious mess of a horse, but…
[Nerida McGilchrist] 16:12:53
I wanted to raise awareness, I guess, in this area of horse nutrition that there are these mycotoxins in ryegrass that can absolutely affect them both physically, so with the staggering and the muscle tremors and the, you know, reactivity to sounds and.
[Nerida McGilchrist] 16:13:15
um, you know, the… any sort of movement. They're overly reactive to things like that, but also in their behaviour, where they… they just don't seem to…
[Nerida McGilchrist] 16:13:25
process information the way they would normally would be able to, and they become very anxious and unpredictable in their behaviour. So if you are experiencing these behavioural changes with your horse, do consider that it could be something coming out of their forage, especially if it is perennial ryegrass forage. They're not the only forages that can cause problems.
[Nerida McGilchrist] 16:13:47
Um, tall fescue definitely has the ergovaline mycotoxins, so you might see some of these same issues occurring on horses that are mycotoxin… on mycotoxin-affected or infected tall fescue, but.
[Nerida McGilchrist] 16:14:02
Just.
[Nerida McGilchrist] 16:14:03
if you see behavioural issues, do consider that it could be mycotoxins. Um, I really hope that I haven't… I haven't talked to you around in circles on this one. There's… there's quite a lot to take in. Um, it is… it is lots of…
[Nerida McGilchrist] 16:14:18
Uh, pattern recognition with it, so, you know, learning to…
[Nerida McGilchrist] 16:14:23
look at the climate and the stage of maturity, or how, um, you know, tall or eaten down your pastures are, and combining that with your horse's behaviour.
[Nerida McGilchrist] 16:14:33
Skittles is having a chat again. Sorry about that, if you can hear her. Skittles!
[Nerida McGilchrist] 16:14:40
Dog dog! Maybe take that bit out, David, so I don't sound like Barnaby Joyce.
[Nerida McGilchrist] 16:14:47
I can't remember where I was up to now.
[Nerida McGilchrist] 16:14:54
Oh, God, I've lost it. You might have to just, you might have to just take that, take that bit out. Anyway.
[Nerida McGilchrist] 16:15:04
I do hope I haven't talked to you around in circles on that one. There's a lot to take in, but yeah, I guess core message is strange behavioural issues. Go and check your pasture or your hay and see if you've got perennial ryegrass in there.
[Nerida McGilchrist] 16:15:15
Because it could be it.
[Nerida McGilchrist] 16:15:16
Thank you so much for being here. If you do know of anyone who's got an overly anxious horse or someone who's struggling with behavioural issues, particularly at this time of year, do share this episode of the podcast with them. I'd also absolutely love you to follow.
[Nerida McGilchrist] 16:15:31
the podcast. Make sure that you don't miss any upcoming episodes, and it also does help us.
[Nerida McGilchrist] 16:15:38
be found on the podcast platforms by other horse owners who might be in need of this information. Thank you again for being here, and I will catch you in the next episode.
Get help assessing your horse's diet and building a balanced feeding plan. Download the MyHappy.Horse app and feed with more confidence.
