Laminitis & Spring Grass: How to Keep Your Horse Safe
Podcast #67
Managing a laminitis-prone horse through spring can feel like a full-time job — especially when pasture sugar levels can change dramatically with the weather.
In this episode, Dr Nerida and Orla talk through the practical realities of managing horses with laminitis and insulin dysregulation, including why frosty nights and sunny days can make spring pasture particularly risky, when grass is likely to be safest to graze, and how grazing muzzles, strip grazing and low-NSC hay can help.
They also discuss clover, forage testing, nitrate risk, exercise and insulin sensitivity, and the challenge of keeping horses eating enough fibre while still controlling calorie and sugar intake.
A practical follow-up to our conversation with Dr Luke Wells-Smith, for anyone navigating laminitis, EMS or spring pasture with an easy-doer.
🤖 If you have questions about laminitis, or any other feeding and nutrition related question, give Dr Nerida AI a go: https://www.myhappy.horse/nerida-ai
💛 And to really look in detail at your horse’s diet, download the MyHappy.Horse nutrition app: https://apps.apple.com/au/app/myhappy-horse/id6633422324
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Happy Horse Nutrition Podcast
Spring Laminitis Management – with Orla
Hello, and welcome to the Happy Horse Nutrition Podcast. It is Friday afternoon, we have Orla back, and we are going to have a chat about laminitis. Because I’ve got laminitis-prone horses, Orla’s got laminitis-prone horses, and we’ve got friends who are going through this at the moment as well. We thought it would be a nice follow-up to Dr. Luke’s episode last week, and hopefully something that’s useful for lots of other people who are trying to manage these beautiful creatures.
ORLA: Headache-inducing creatures, Nerida.
NERIDA: How did you describe yourself today? An EMS girlie.
ORLA: Yeah, I am now an EMS girlie. I’ve always talked about it, but now I am living the life.
NERIDA: Living the dream. Welcome to the club, by the way.
ORLA: It’s great. It’s so great.
NERIDA: I’ve had membership since I was at university. Late 90s.
ORLA: I swore I’d never do this. And now I’m up to my neck in it. Speaking to Luke yesterday, he was like, I told you so!
NERIDA: It’s hard. I mean, they’re such beautiful horses, and then they get these problems. I said to Ryan the other day, I’m only owning thoroughbreds from now on – and then we’ll get a heap of people going, I’ve got a thoroughbred and it also has laminitis, so you’re not completely protected. It was actually really fascinating, Luke saying that there’s very old evidence of laminitis in horses, which makes sense. The physiology of their single toe is going to have that potential for laminitis.
Why Spring Is the Highest-Risk Season
But this time of year is particularly hard. Orla and I have done a lot of pasture sampling together back in the day, and spring is more dangerous than the other seasons. My horses – I had three at the time – they all got laminitis in the middle of summer, so it’s not to say that spring is the only time, by any means, but it is riskier because of the weather.
I’m looking at around 350 pasture samples here – a lot of Hunter Valley data that we collected over some of the years that you and I worked together. In summer, the non-structural carbohydrate content was 7.5% on average. Autumn was 8.6%. Winter was 13.9%, and spring was 16.5%.
So there’s this tendency for spring to be much higher risk. The reason, particularly in climates like ours, is that you come out of winter and by the time we get to spring, the days are getting reasonably long. The plants have got all this daylight time to sit there photosynthesizing and making their own food during the day. Then overnight they use up that carbohydrate to stay alive – to grow and breathe and do all the things that plants do.
But in springtime, it can still be so cold. We can get frosts and below-freezing temperatures well into spring. If you go below freezing, a plant essentially goes into suspended animation. It doesn’t do anything. And then when it defrosts, it starts to photosynthesize again.
So what happens is like a step. They might start at, say, 8% non-structural carbohydrate, photosynthesize for the day and get up to 12%, then get frozen overnight so it stays at 12%, and then the sun comes out again the next day and they make more.
ORLA: So we’re not actually ever going back down to that 8%? We’re just staying at the level they went to sleep at?
NERIDA: When it freezes overnight, yes. And then if you get another frosty night and a sunny day, it goes higher again. And if you get another one, it goes higher again.
What You Can Actually Do: Managing Pasture Access
So what I mainly want to talk about today is: what are the things we can do during springtime to keep these really laminitis-prone horses safe?
I get to this time of year and I really love September and I really don’t love September. In the Southern Hemisphere, that’s our first month of spring. The days are so beautiful and they’re sunny and they’re warm, but then we can get a lot of below-freezing nights.
Last spring, 2025, we had multiple frosty nights and then long sunny days. If you look at a lot of hay analyses from last season, they’re massively high in non-structural carbohydrate – 23, 25%, and some of the hay that racing stables I work with are using is over 30%.
Luke spoke last week about the stages of laminitis, and the first stage he talked about was exposure to risk. And this is where keeping a mental log of the weather becomes so important – when was it frosty last? How safe or unsafe is it likely to be for my horses to be grazing green pasture right now?
ORLA: So to me, risk starts in winter. That’s when I have to be on point.
NERIDA: The difference between winter and spring is that days are so short in early winter. The shortest day of the year is in the first month of winter, and June and July never really worry me because when the days are really short, there’s not as much time for the plants to photosynthesize and build up non-structural carbohydrates.
But as the days get longer coming into spring, that changes quickly.
The key rules to keep track of:
Frosty nights increase the risk. Runs of frosty nights massively increase the risk.
Cloudy days make it a lot safer – there’s not as much sunshine and not as much photosynthesis.
Early morning grazing – a couple of hours before sunrise to a couple of hours after sunrise – is your lowest non-structural carbohydrate window, provided it hasn’t been freezing overnight.
If it hasn’t been freezing, the plants will still metabolize and burn up their sugars overnight, so by very early morning they should be safe to graze. But if you’ve had four frosts in a row, there’s no way I’d give them fresh grass. They just have to eat their hay.
What I’ll tend to do is move a strip grazing fence on mornings like this morning – give them enough grass to eat for a few hours until a couple of hours after sunrise, and make sure I don’t give them so much that they’re still eating until midday. They’ve got Rhodes grass hay and some teff straw and lots of other forage they can chew on when they’re not eating the green grass.
Knowing Your Individual Horse
It does depend on the horse. Popcorn, bless her laminitis-prone toes, is quite sensitive. Within the last six months she’s had a pulse and been a little bit scratchy at the trot. She’s probably a condition score of 6 – not hard cresty in her neck, she doesn’t have the fat deposits above her eyes, but she’s a lot more filled in above her eyes than the other horses. They’re smooth, not popped out, but you wouldn’t be able to hold a teaspoon of water in there.
I’m a lot more cautious with her than with Poet, who hasn’t had a pulse even in the last 10 years. He’s ribby, he’s in work at the moment – he should actually have decent insulin sensitivity. I let him out today in the big paddock because it’s been cloudy all day.
You become obsessed with the weather and thinking about how it’s going to be affecting the grass, and then how the grass is going to affect the horses.
Grazing Muzzles
The other thing you can do with these horses – and I really should do this more with Popcorn – is when you’re a little bit unsure about whether it’s safe, put a grazing muzzle on them. You’re giving them that physical and mental stimulation of being out with their herd mates and grazing, but they’re not actually able to eat very much.
They get those few hours of access to pasture first thing in the morning when it’s safer to graze, but for specific horses that are more prone, and particularly the ones that are more overweight, muzzling them means they don’t get as much of the fresh grass as the other horses. Then when you bring them off, they’ve had very little grass and they can go back to eating their known safe hay.
The known safe hay is really the key in all of this. Because we have to fill them up with forage. You can’t just not feed them to keep them safe from laminitis – they probably won’t get laminitis, but then they’ll get gastric ulcers and all sorts of behavioural issues and hindgut dysbiosis issues. You’ll cause more problems than you prevented.
Orla’s Situation: Managing Porky Pig
ORLA: So my horse is in the house paddock by himself, because we just need to get on top of this. He’s got his friends across the road, but nothing in his paddock. And as I told Nerida last week, I was under the impression I was feeding straw, and we found out there was oaten hay – surprise, surprise, that’s why his pulse wouldn’t go away. He’s now down to lucerne haylage and lucerne, and then Multicubes, because that’s all we can get at the moment. So he’s not got great diversity, but we’ll fix that. The question is, for a 430 kilo horse, how are you getting 7 kilos of fibre into them over 24 hours when you’re trying to get the weight off them? Make that make sense.
NERIDA: How are you spreading it out enough? Yeah.
ORLA: At the moment, because I’m here, I’m going out every three hours and giving him a little bit.
NERIDA: Can you find actual straw?
ORLA: Not at the moment. And then the straw I did have when we could get it had lots of wheat grain mixed through it.
NERIDA: This is where everyone who has a laminitic horse needs a shed. Because to have a supply of known safe hay on hand –
ORLA: Well, funnily enough, we’re getting a shed built now, because Matt has to buy the hay.
NERIDA: This is a good plan! Because it’s really important – and just in general, outside of talking about spring with laminitic horses, if you’ve got a horse prone to laminitis, just make sure you’ve got at least a couple of days’ worth of hay on hand. Because if the worst happens, you can stop. Luke and I spoke about this last week – at any point, you can step in and go, okay, stop. If you can find whatever it is that’s triggering their insulin response and remove it, you can literally just stop the disease. But you can’t do that unless you’ve got something to feed the horse that you know is safe.
The Forage Dilemma: Lucerne vs. Low-Energy Options
Rhodes grass hay is so useful – very low in non-structural carbohydrate, though horses don’t tend to like it very much because it’s just not sweet.
Lucerne from a non-structural carbohydrate content is good, because it tends to be nice and steady in its NSC content. It doesn’t vary a whole lot, and it’s usually below 10%. But the problem, of course, is that it’s so high in calories. So you get into this situation where you’re needing to restrict the amount of forage because of the calorie content, but then you’re also battling: how do I have this horse eating enough over a 24-hour period so it doesn’t get gastric ulcers?
The long-term answer is really to find a low-quality, low non-structural carbohydrate hay so that they can have as much of it as they like. Just keep looking for Rhodes grass hay, or get hay tested so you know exactly what you’ve got.
ORLA: And if you’re sending your partner in to buy hay – don’t. Ask multiple people in the store. Don’t just ask the one person.
NERIDA: There’s the golden piece of advice for the episode.
Exercise and Insulin Sensitivity
The other thing I want to mention, and one of the things that’s making me feel better about Poet and Popcorn coming into this spring, is that they’re both in work. My nieces want to go to pony camp, so I’m strapper for them at the moment. We started at about seven minutes of trotting and we’re up to about half an hour of trotting and cantering now.
That helps so much, because when you’re exercising them, you are improving their insulin sensitivity. So as soon as your fella is sound and you’re not going to risk actually hurting his feet by making him exercise, get Matt on a bike.
ORLA: I’m looking at the bicycle. We’re going to learn to run along with the bike, even though Matt is really uncoordinated. He has many scars from doing this.
NERIDA: An uncoordinated guy on a bike with a horse. What could possibly go wrong. He can be like that guy we spoke about in Sydney with the pony.
A Note on Nitrates
ORLA: High nitrates – should we mention that?
NERIDA: Yes, nitrates are the form of nitrogen that the plant’s roots suck up out of the soil. They use that nitrogen to make protein, but if it’s cloudy and they can’t photosynthesize – because making protein takes a lot of energy – they’ll still suck nitrate up but they’re not actually turning it into protein. So it just sits around in their leaves and waits until they can turn it into protein. That’s great for the plant, it’s terrible for the animals eating it because it’s quite toxic.
I worked for many years with a big stud farm in Saudi Arabia, and if we were not on top of nitrate content in the hay, we saw a lot of laminitis even in young racehorses – nothing to do with insulin sensitivity, just nitrate toxicity. Once we started testing all the hay and keeping it below 500 parts per million of nitrate, we didn’t have those problems anymore.
Unfortunately, nitrate is highest first thing in the morning – so you’re trying to manage sugar intake and non-structural carbohydrate intake, and you could inadvertently be exposing horses to nitrate at the same time.
I don’t worry about nitrates on my place because our soil tests show nitrogen isn’t super high, but if people are fertilizing their pastures with nitrogen-based fertilizers, or if you’ve been through prolonged drought conditions (soils accumulate nitrogen in drought), it is something to be aware of. I always say to people, always get your hay tested for nitrate, especially if you’re feeding a laminitic horse.
The Clover Question
ORLA: Can you talk to me about clover? Because technically it’s a legume and legumes are great.
NERIDA: Well, clovers are clover, and lucerne is a legume but it’s a medic. They’re in the legume family but they’re different plants. And clover – I actually don’t have a lot of experience with clover hay, because we don’t tend to use a lot of it where I’m from, and I haven’t seen a lot of analyses.
But the research shows that clover will accumulate a lot of starch – enough to trigger laminitis. I can see a paper here saying that white clover accumulated something like 14% more non-structural carbohydrate than red clover. And I think white clover is probably what you’ve got.
ORLA: Yeah, it’s white.
NERIDA: Clover is a completely different beast to lucerne. A lot of people think lucerne is unsafe for laminitic horses, but lucerne is actually safe. I love lucerne for laminitic horses – it does lots of nice things in their diet and it tends to be one of the more consistent forages in terms of non-structural carbohydrate. Clover is a completely different story. Do be careful with clover.
I’m pretty lucky here – we don’t have a lot of clover. We have a lot of burr medic, and it seems to be okay, but I’ve never actually tested it, so don’t go away thinking Nerida said it’s okay to graze your laminitic horse on burr medic, because it may not be at certain times of year.
Summary: What to Watch For
The general rules:
Early morning (two hours before sunrise to two hours after sunrise) is your lowest non-structural carbohydrate window
Frosty nights increase NSC consecutively over however many days you get them
Cloudy days are good – less sunshine, less photosynthesis
White clover is risky – treat it differently to lucerne
Know your individual horse – some are more sensitive than others
Have safe hay on hand at all times so you can act fast if you need to
And please – if you do have a laminitic horse, don’t be hard on yourself. This is hard. I’m a professional nutritionist and all three of my horses got laminitis at the same time. It’s not something you’ve done. It is genuinely difficult to keep them away from the risk factors, especially at this time of year.
If you’ve figured out something that works really well for your situation, share it in the comments – we would love to hear your hot tips.
Thanks so much for being here, and I’ll catch you next time.
ORLA: See you!
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