Preventing Gastric Ulcers in Horses: 4 More Nutrition Strategies
Podcast #63
Preventing squamous gastric ulcers takes more than just feeding enough forage. In this episode, Dr Nerida explains four additional nutrition strategies: feeding a balanced diet, controlling grain and starch intake, supplying high-quality protein, and using lucerne or alfalfa strategically.
Plus she covers why grain is not automatically the problem, how key nutrients support stomach repair, and why lucerne is so valuable for gut health.
Here are some of the papers referenced:
Effects of feeding alfalfa hay in comparison to meadow hay on the gastric mucosa in adult Warmblood horses https://pferdeheilkunde.de/files/20200105.pdf
Evaluation of diet as a cause of gastric ulcers in horses https://pubmed.ncbi.nlm.nih.gov/10895901/
Risk factors associated with equine gastric ulceration syndrome (EGUS) in 201 horses in Denmark https://pubmed.ncbi.nlm.nih.gov/19927579/
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Hello, hello and welcome back to the Happy Horse Nutrition Podcast. I’m Dr. Nerida, PhD equine nutritionist, founder of the MyHappy.Horse Nutrition app and lover of good nutrition science. Today we are going to dive back into the science around ulceration to look at four more important aspects of horse nutrition for preventing squamous gastric ulcers.
Hopefully you managed to catch the podcast last week where we talked about the three most important things you need to do to prevent squamous ulceration, which is the ulceration that happens in the top part of the stomach and is normally caused by stomach acid splashing or squeezing up to the top part of the stomach and literally burning holes through the gut wall.
In case you didn’t catch that podcast, which was episode 62, the important aspects of nutrition for preventing this form of ulceration are all centred around a horse’s forage intake, because it is forage that keeps the stomach full and stops the acid from splashing around. Plus, when horses chew forage, they also create saliva, and the saliva buffers and dilutes the acid in the stomach and makes it less likely to create ulceration.
So before you even begin to think about what is going on in your horse’s feed bin, you must get the forage part of your horse’s diet right, making sure they are getting enough forage, that they aren’t going too long between forage meals, and that you are feeding hay before and after riding.
So with forage covered, today what we are going to talk about are the other things you can do to further reduce the risk of squamous ulceration.
1. Feed a Balanced Diet
If you work your way through a lot of the nutrition science in this area of gastric ulceration, what you’ll notice is that there are multiple studies showing that when horses are fed either a grass hay only diet, or a diet with a high percentage of straw in it and no supplementary feed, a really high percentage of those horses are affected by squamous ulceration. When we combine that with the Icelandic study that I talked about quite a lot in episode 62, which found that horses getting supplementary feed had reduced ulceration, I can’t help but think that the difference between the diets that are forage only and the diets that have some level of supplementary feed added to them is the balance of nutrients in those diets.
We know that there are lots of nutrients that are crucial for wound repair. I’m just going to take one as an example, because it’s a really good one for this situation. Let’s look at zinc. We know zinc is critical for wound repair. Zinc-deficient humans have a lot of issues with wound repair, and I see this in horses as well. When we have horses with bad leg injuries, if they’re not on balanced diets and they don’t have their zinc requirement met, those injuries take a long time to heal.
I remember when I was a kid, my beautiful Coco, the horse I got when I was 8 years old, put her leg over a wire fence and ripped all the skin off the front of her cannon bone on one of her hind legs. I vividly remember my dad having to cut the proud flesh off that leg time after time after time because it just wouldn’t heal. Looking back now, after going back as a seasoned nutritionist and actually sampling pasture and hay off the family farm and seeing how low in zinc it is, I know that she would have been really zinc deficient. Her hooves used to break apart really easily as well, which is another sign of zinc deficiency.
So when horses are zinc deficient, wound healing just takes forever. And that’s what we can see on the outside. The same is true for wound healing that is happening on the inside of our horse. Ulceration is essentially just an open wound in the stomach, and squamous ulcers are wounds in the top part of the stomach. So if you’ve got horses who are zinc deficient, they will have a hard time repairing any damage that might occur in their stomach. This means that if they get a little bit of acid splash one day and there’s some acid burn, if they’re zinc sufficient and their diet is balanced, they’ll be able to repair that damage and it won’t turn into an ulcer. But if you’ve got a horse that is getting a little bit of damage that it can’t really repair, and then it gets a little bit more damage and still can’t really repair it, after repeated insults of acid on that forming wound, it will become an ulcer.
My mind goes to zinc because I’ve looked at forage analyses from all around the world, and there is nowhere in the world where zinc is consistently high enough to meet a horse’s daily requirement. In parts of Australia, we can see zinc less than 10 parts per million, or 10 milligrams per kilogram, and a horse’s minimum daily requirement is 40 milligrams per kilogram of feed per day. This is not just isolated to Australia. Lots of forages in the US can be just as low in zinc. The farms I work with in Japan, where we do a lot of pasture analysis, also have low zinc as a consistent problem. Hays coming in from the US and Canada to Japan are also consistently low in zinc. Forage analyses from parts of Europe are also low in zinc. It is a worldwide problem for horses.
So it makes sense to me that when you feed a horse a forage-only diet, even though the forage is doing all that beautiful work of keeping the stomach full and creating saliva and stopping the acid from splashing around, the research is telling us that horses on forage-only diets are going to be at high risk of gastric ulceration. We have to get their diets balanced up.
This is a big part of what we do as equine nutritionists. A big part of our job is just filling up the gaps in a horse’s diet that are left there by forage. Copper and zinc are very common minerals to be low in forages, and then there are lots of vitamins, depending on how long a hay has been stored, that will also become very low in a forage-only diet. So we must feed a balanced diet.
This is a big part of what the MyHappy.Horse Nutrition app does. You can put your horse’s diet in, put in its pasture and its hay, and you will actually physically be able to see the gaps in a horse’s diet. You’ll be able to see whether zinc is too low, or whether you are actually meeting a horse’s requirement for zinc with what you’re feeding. We can balance up a diet in multiple ways. We can add a complete fortified feed to the diet if a horse has got high enough energy requirements to justify it. We might add a balancer pellet, which is a really convenient way to fill up the gaps left by forage-only diets. Or we might use a very low dose vitamin and mineral supplement that can be fed in a small amount of carrier feed, or mixed into a combination of different fibres and some protein meals.
There are literally thousands of products on the market for balancing a horse’s diet, and this is a big part of why horse nutrition can get confusing. If you don’t know and can’t see what you’re adding to your horse’s diet, it’s a little bit hard to determine whether you’re actually meeting your horse’s full nutrient requirements. This is where either using our app, or other nutrition calculators on the market, or working with a real life nutritionist for a diet consultation, can make all the difference. Whichever way you choose to do it, just make sure that you are actually feeding a balanced diet to your horse.
2. Control Grain Intake
This podcast series actually started because I saw a post on Facebook from a lady saying that it was the third time this year her horse had been diagnosed with gastric ulcers, and she was asking people what she should feed. A lot of people will jump straight to saying go grain-free, don’t feed any grain, and there is a school of thought that grain causes ulceration. But if you look at the research, that’s not quite true.
The Icelandic study we spoke about in episode 62 actually showed that horses getting some level of supplementary feed had a lower incidence of gastric ulcers. As we just talked about, I think at least part of that will be because those horses had a more balanced diet. But the interesting thing was that most of those supplementary feeds were some sort of processed grain feed. So horses that had processed grain added to their diet had a reduced risk of ulceration.
I don’t think that grain reduces the risk of ulceration. The science just doesn’t show us that it increases the risk of ulceration unless you feed too much. Like all things, in moderation it is going to be safe. This is of course depending on the horse being able to eat grains in the first place. There are some horses, laminitic horses, PSSM tying-up horses, and a bunch of others that for metabolic reasons can’t have grain. But for horses that can safely eat grain, you can feed it without increasing the risk of gastric ulcers, as long as you feed it in a controlled manner.
Research done in Denmark in a survey of hundreds of horses found that when we feed more than 1 gram of starch per kilogram of bodyweight per meal, the risk of ulceration was tripled.
If we look at what 1 gram of starch per kilogram of bodyweight per meal actually means in terms of kilograms of feed, it all depends on what percentage of starch a feed is. If we’re talking about a performance horse feed that contains grain but is relatively low in starch, you’re looking around that 20% starch mark, which is 200 grams per kilogram. For a 500 kilogram horse, two and a half kilograms per meal is going to be that upper level. So if you’re feeding a 20% starch feed and you’re feeding any more than two and a half kilograms per meal, you’re potentially tripling the risk of ulceration in that horse.
When we look at higher starch feeds, around 35% starch, which is around where a lot of racing feeds will sit, we have to bring our amount of feed down to just 1.5 kilograms per feed to stay under that threshold. So if you’re feeding one of those high starch feeds and you’re feeding more than 1.5 kilograms per meal, the risk of ulceration is potentially going to be tripled based on this study.
Now, the grain itself doesn’t cause the ulcers. It’s the amount of grain we’re feeding. Part of me does wonder whether it is a function of the starch itself, which it could be. When grain goes into the stomach, there are a lot of bacteria that live there, and those bacteria will ferment starch and produce volatile fatty acids. Those volatile fatty acids, when they come into contact with the gastric acid, change form, and when they touch the cells in the upper part of the stomach they can actually be absorbed into the cells, make them inflamed, and make them more prone to acid attack. So there is good physiological basis for saying that feeding grain will increase the risk of gastric ulcers, and that may be part of why the more starch you feed, the higher the risk, because you’ve got more starch fermenting in the stomach at any one time. But part of me also wonders whether it’s simply a function of the fact that if you’re feeding more grain, you’re feeding less forage. I suspect it’s probably a little bit of both.
So the best thing you can do for horses in terms of reducing gastric ulcer risk from grain specifically is to control the grain intake. In racehorses, I do a lot of work with racehorses, and I cannot get them to race well unless we feed some grain in the diet. It has to be in the diet for some performance horses because it’s such a good source of glucose, which they use to build their muscle glycogen. But we have to feed it in a way that is sensitive to the gut’s physiology and to the fact that if we feed too much of it, we’re going to cause a lot of problems, one of them being an increased risk of squamous gastric ulcers.
There are actually multiple studies showing similar results to the Icelandic study, where when hay is fed with a fortified grain-based feed, ulceration is lower in the group of horses getting the grain plus the hay versus the hay only. Again, it’s all interwoven. When we feed grain, we potentially increase the risk of gastric ulcers from one perspective, but we’re also bringing in a lot of other nutrients, and if they’re fortified grain feeds, we’re also balancing the diet. So a part of what they would be seeing in those studies where they add grain to a hay-based diet is simply that they are balancing the diet, so horses have got their zinc requirement met and all the other nutrient requirements they need, and together that is reducing the risk of ulceration.
All that to say, don’t panic about grain in diets. If you feed too much grain, then yes, you have a higher risk of gastric ulceration. But when you feed grain well, and particularly when you feed it as part of a balanced diet where your horse is still getting plenty of forage, and the grain-based feed is actually part of making sure that your horse’s nutrient requirements are met, then it becomes part of the solution to gastric ulceration as opposed to one of the causes.
There is no harm if you would prefer to stay away from grain-based feeds, or if you have to feed a grain-free feed because your horse has got other issues that prevent it from being fed grain. Again, a lot of it comes back to just making sure that you are feeding a balanced diet.
3. Feed High-Quality Protein
In episode 52 of the Happy Horse Nutrition Podcast, I talk about protein quality and how protein is not just protein. Proteins are made up of building blocks called amino acids, and there are 20 different amino acids. Ten of them we call the essential amino acids, the other ones we call the non-essential amino acids. The essential amino acids a horse must get in the diet. The non-essential amino acids they can actually make for themselves in their body, so a horse is not reliant on them being in the diet.
Some of those amino acids are really important in gut health. The amino acid glutamine is needed to repair any damage that might happen to the gut wall. The epithelial cells, the lining of the gut, have a massive requirement for glutamine. If they’re not getting enough glutamine, they can’t turn themselves over and can’t replenish themselves quickly. So if there is some damage to the stomach wall and it doesn’t repair quickly, and then the next day there’s a little bit more damage and a little bit more damage, that’s how the ulceration happens. Glutamine is super important.
It’s an interesting amino acid in that it’s one we call conditionally essential. It’s actually in the non-essential category because when a horse needs it, it can make some in its own body. But there are certain conditions where a body’s requirement actually outstrips the horse’s ability to make it for themselves. Anytime there is some stress, so high level performance horses under a lot of work pressure, young horses growing rapidly, and horses that are sick, they have increased requirements for glutamine. In those situations, horses will actually need a dietary source of glutamine. The role that glutamine plays in gut health is a big part of the reason why you will see this amino acid added to a lot of gut health supplements, because the science tells us that amino acid is critically important for repairing the gut wall.
There are a bunch of other amino acids that are really important for stomach health. The bottom part of the stomach needs to produce its protective mucus to stop it from ulcerating and glandular gastric ulceration occurring down in that part. Amino acids like threonine and proline and serine, which you will also see in a lot of gut health supplements, are really important for that protective mucus.
For the top part of the stomach, horses need specifically glutamine, but they also need the broad spectrum of the essential amino acids because cells are made up largely of protein. We need to make sure that those cells have got every building block they need so that they can continually repair and replenish themselves and make sure that if there is some damage that occurs in the stomach, they can repair it quickly.
Your highest quality proteins that we see commonly in horses’ diets are things like soybean. Soybean is the highest quality plant protein we can get, and quality is based on how much of the essential amino acids they contain and how closely those essential amino acid profiles match what a horse actually needs. Soybean contains the best profile of essential amino acids for horses out of all of the other plant proteins available. And then the highest quality protein that we would see used in some parts of the world is whey protein. Whey protein is really rich in essential amino acids, and particularly the essential amino acids needed for gut health. This is again part of the reason why you will see whey protein used in gut health supplements.
When we have really good protein in our horse’s diet, it just means that we’re giving them the building blocks to keep rebuilding and repairing their stomach lining so that it can stay very healthy, and if there is any damage in there, it can be repaired quickly before it turns into a big problem.
Part of the reason why we see horses on straw-based diets ulcerate so much is potentially because of a protein and essential amino acid deficiency. Straw is really low in protein, and if we’re feeding horses diets that are predominantly straw, it’s certainly within reason to expect that those horses would be protein deficient. It’s part of the reason why, when we are feeding weight loss diets, which I talk about in episode 58, we are so focused on making sure that weight loss diets have got all of the nutrients a horse needs and are only restricting calorie content, not restricting things like protein and amino acid intake. Because if we’re restricting their protein and amino acid intake too much, we will start to cause deficiencies of essential amino acids, and one of the manifestations of that is potentially gastric ulceration, which is certainly what has been reported in research looking at feeding high percentages of straw to horses.
4. Feed Lucerne (Alfalfa) Hay
The fourth and final thing on my list for helping our horses avoid squamous gastric ulceration is to feed lucerne, or alfalfa hay, depending on what you call it.
A big part of why lucerne or alfalfa will help horses avoid squamous gastric ulceration is because it’s beautifully rich in high quality protein. It’s going to be directly feeding the cells lining the stomach and making sure that they are having their requirement for essential amino acids met.
Lucerne has been shown in multiple research studies to be beneficial for both preventing ulceration and, amazingly, for healing ulceration. There are some cool studies done back in the early 2000s, which always felt like really recent studies to me until I looked them up earlier and realised they are now 20 years old, which makes me feel old. Those studies show that when horses were fed lucerne or alfalfa hay during a rest period, the horses on the lucerne were actually able to repair ulceration that was already present in their stomach. That was an amazing finding, and it’s always stuck with me. When racehorses come out of training for short periods of time and are out spelling, I always want to make sure that there is some lucerne in their diet for that reason.
But there is always a but, isn’t there? There will be situations where just feeding lucerne is not going to be enough to repair ulceration. I was able to personally test this out with a little horse named Galaxy.
I’d taken our Spotty the pony to our vet, Dr. Doug, on a gastric ulcer scoping day to see what we could see in her stomach. Spotty has the Culicoides sensitivity, so the Queensland itch or sweet itch or summer itch, and she’d come from friends of ours who had done a beautiful job of trying to stop her from being bitten by the midges as much as possible. She just seemed to me like something wasn’t quite right, and interestingly, and probably not surprisingly, she actually had glandular ulceration. We’re starting to understand that glandular ulceration is more of a stress-related condition, and it was not surprising really that she had it from being constantly itchy and not necessarily being able to scratch. I am also allergic to midges, so I completely understand that awful feeling.
Anyway, while we were at the vet’s, there was this little pony there named Galaxy, and her family had brought her in on the recommendation of their vet to see if she had ulceration. This little horse lived at pasture but wasn’t supplementary fed, which is interesting because it ties into horses just on grass-based diets being at high risk of ulceration. Her stomach was ulcerated from top to bottom. She had serious squamous ulcers, she had serious glandular ulcers, and she wasn’t in work, she was at pasture 24/7, she had a paddock mate so she wasn’t by herself. Her behaviour evidently was terrible, and that was a big part of the reason why they brought her in, because she’d become quite unsafe for her young little rider.
When they found all of this ulceration, they weren’t able to afford all of the treatment. I’d mentioned to Doug that she’d be an interesting little case study to see what we could do with those ulcers on a balanced diet. So when Doug called me a couple of weeks later to say they were wanting to rehome her, I said sure, I’ll take her and see what we can do with her.
I spoke to Doug about getting treatment sorted for her, and we wanted to use the injectable omeprazole and then scope her on a regular basis to see how we were doing. And then COVID pretty much shut a lot of stuff down. I couldn’t get the omeprazole, and there were no scoping days because none of us were allowed to be anywhere near one another.
So Galaxy lived here for about 7 months. She was fed lots of lucerne and she was on a balanced diet. I did lots of research around every nutritional strategy I could use for this horse. She was on gut supplements that had plenty of amino acids, I was bringing in vitamin C to help with wound healing, and I knew that her zinc requirement and all the other nutrient requirements were met.
After about seven months, she looked an absolute picture. She was glossy and shiny, and her behaviour had actually calmed down, though a good portion of that was just that she hadn’t had many ground rules with the family she was with, so when she had a few more boundaries things improved a lot. And honestly, there are photos of her still on my phone. She looked amazing.
When we did eventually get her back for scoping, her stomach was as ulcerated as it was when we first started. I nearly died. I honestly couldn’t believe that we hadn’t made any headway whatsoever with healing those ulcers.
Doug then took her, put her through treatment, got her gut right, and she got rehomed again with a young lad that was doing a lot of work with her. The last I heard she was doing really well.
All of that to say, lucerne is great, and there are studies to show that it will help with ulcer repair in some situations. But don’t hear that and think that you don’t need to treat horses that have got ulceration, because there is definitely going to be a need for treatment. Galaxy was a perfect example of that. You couldn’t have had a more perfect diet for healing ulcers, and yet those ulcers still persisted in both the top and the bottom of her stomach.
Lucerne does play a really important role in diet though. Studies show that if you feed lucerne with grain, it will buffer the gut more and seems to reduce that negative impact of the grain I was talking about before, where the grain ferments and produces volatile fatty acids that then inflame the lining of the upper part of the stomach and make it more prone to acid attack. It looks like when we feed lucerne with our grain, we reduce some of that negative impact.
There is a highly cited paper, Libet 2007, presented at the American Association of Equine Practitioners back in 2007, which showed that horses who were fed a pelleted feed plus lucerne, only 8% of those horses were found to have gastric ulceration. But when that same pellet was fed alongside grass hay, 75% of the horses ended up with gastric ulceration. It’s a massive difference.
There are probably many reasons for it. Lucerne, as we’ve already talked about, is going to be adding in high quality protein. It also does this beautiful thing of buffering the stomach itself. Its protein and its calcium are actually natural buffers. There is research showing that when lucerne was fed with feed, it actually maintained a higher gastric pH for 5 hours after feeding compared to when feeds were fed with grassy hay.
I don’t know if you can tell, but I absolutely love alfalfa, and I use it everywhere I can in horses’ diets. It does need to be fed in moderation, and again, this is where an app like MyHappy.Horse just comes in so handy. You can feed ingredients like lucerne with confidence, knowing that you are gaining the benefit of having those ingredients in the diet without overdoing them. In young horses, if you feed too much lucerne, you’re going to put too much calcium in the diet and push the calcium to phosphorus ratio too high. In horses that are working hard in hot, humid conditions, if you feed too much alfalfa, you push protein too high, and when protein is high in their diet they have to urinate a lot to get rid of the excess nitrogen, they dump a whole heap of electrolyte, and then they’re at really high risk of tying up. So it’s a beautiful ingredient, you just can’t overfeed it, and this is where calculating your diet accurately becomes so, so important.
I did smile to myself reading a German study presented in 2020, which was actually a really good study. There was some previous research in young horses that showed that feeding alfalfa in the form of chaff actually caused damage to the lower glandular region of the stomach and caused ulceration. There are some people who will say don’t feed lucerne chaff because it causes ulceration. Now, anyone who feeds chaff or chopped hay a lot knows that occasionally you’ll get a bag where the pieces of fibre are quite sharp, made out of reasonably old lucerne. So there’s every chance that that earlier study used one of those sharp chaffs and was causing mechanical ulceration.
This German study set out to find out whether horses on alfalfa-based diets actually sustained damage in the glandular section of their stomach. What the study found, thankfully, was that there was no such damage. The horses on the alfalfa-based diets had the same glandular health as the horses on the grassy-based diets.
I smiled reading the conclusions of that paper, which started out by saying, “As alfalfa is a plant which grows in hot conditions, it might be a feedstuff of interest in equine nutrition.” It just highlighted to me how different nutrition is around the world depending on what grows naturally. Australia is so hot, and I know you feed a lot of alfalfa in California and other hot areas of the USA. I don’t know how you do horse nutrition without alfalfa. But if anyone in Germany happens to be listening to this, alfalfa is absolutely a feedstuff of interest in equine nutrition. It’s an amazing ingredient. It can do so much in horses’ diets and definitely plays a role in reducing the risk of squamous gastric ulcers.
I’ll finish by adding my favourite piece of advice to horse owners, and that is to make sure you feed lucerne or alfalfa hay before you ride and also after you ride. I talk about that in detail in last week’s podcast, episode 62. I also did a whole podcast on it in episode 3. In terms of reducing the risk of squamous gastric ulcers, feeding hay before you ride, and particularly feeding lucerne hay before you ride, is probably the single best management change you can make. So if you’re not doing that yet, please do that. Your horse will absolutely thank you for it, and they will show you how grateful they are for that change in their management through their behaviour when you’re riding them.
Wrapping Up
I hope all of that helps. We did just cover a lot. Remember that the MyHappy.Horse Nutrition app is absolutely a friend when you’re going through and working out how to feed a balanced diet. It will help you make sure that you’re not overfeeding grain, so you’ll be able to see whether the amount of grain in your horse’s diet is in the red or the green. If you’re in the red and feeding too much, you need to find ways to bring that down. It will help you find high quality protein and show you how much protein and the amino acid lysine you’ve got in your diet. And the last thing we talked about was to feed lucerne. It’s such a good ingredient and so handy in pretty much every horse’s diet, but you can’t overfeed it. So do the calculations on your horse’s diet, make sure that you’re not over-supplying calcium or protein, but that you’re getting enough lucerne in there to have the positive impact it can have on your horse’s gastric health.
I hope that helps you. I know there are always so many questions around gastric ulcers, and with good reason. It is such a big problem for our horses just because of the way their gastrointestinal physiology is set up. But I hope you find some bits and pieces in there that will help you with your own horses. Thank you so much for listening. If you know anyone who’s struggling with their horses, I’d absolutely love you to share this episode with them, and if you find the time, we would love you to rate and review the Happy Horse Nutrition Podcast. Thanks again and I will catch you in the next episode.
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