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For many horses, summer and spring are synonymous with lush pastures, and unfortunately for just as many of their owners, it is associated with a range of concerns about the sugar level in the grass. But what is the actual problem with horses and sugar?
Although horses are naturally used to being outdoors year-round and grazing, we must admit that the way we keep horses today is very far from the wild horse.
Our horses move less, and - unlike in nature - they virtually always have food within reach, meaning they don't have to travel far for sustenance. This can result in our horses becoming a bit too well-fed, and combined with the high sugar content in spring and summer grass, it can unfortunately create favourable conditions for conditions like laminitis.
But sugar in itself is not the culprit - it's the quantity, explains Susan Helany, feed consultant at Nordic Horse.
"All horses need sugar in the sense that it's a nutrient they use to produce energy. Horses also consume sugar in autumn and winter through their haylage or hay. Therefore, we prefer to see the sugar content appropriately low - we say a maximum of 10% in haylage or hay - and it's not because sugar is exclusively bad. It's part of the horse's daily intake of food - both in summer and winter - so the problem arises when we have horses that are overweight, and sugar intake, among other things, can cause insulin dysregulation," she explains.
You don't need to try to remove all sugar from your horse's diet, which would also be difficult as many of the horse's natural food products contain certain amounts of sugar, but you can try to minimise the intake.
"It's about quantity and context. Sugar is not definitively bad, but it's not definitively good either, because it's about the individual horse, how much intake there is, and how it's distributed," says Susan Helany.
As temperatures rise, a series of changes occur in both the sugar content and nutritional value of the grass. Additionally, many horses spend more time outside when temperatures rise, meaning more time to eat the lush grass.
"The rule of thumb is that sun equals sugar production, and warmth equals growth. The risk with the sugar in the spring is that all winter we have had cold temperatures with no grass growth. Then spring arrives - especially now with sunny days and relatively cold nights - and the sugar content in the grass increases dramatically," explains Susan Helany.
When we have sun and cold, we have sugar production, but there is not much grass growth, so the sugar accumulates. The sugar comes when the sun shines, so there is a production of sugar through photosynthesis. That's why it's not only in spring that we can run into problems, but also in autumn and winter if the horse has access to grass.
When the sun shines, we have sugar production. What determines if the sugar accumulates or is used for growth is whether it's cold or warm, and if it's warm, the sugar is used for the grass to grow. If it's cold, it accumulates in the grass until it's warm enough for growth.
There's no doubt that there are also numerous positive effects when our horses are on full-time grass - or something similar - over the summer, but there are several considerations we need to take into account. This applies whether we're dealing with a warmblood horse competing, or a coldblood horse mainly used for rides. The extra hours outside allow the horse to move around and socialise, and there are several beneficial nutrients in the grass. "The challenge with our horses today is that they are often in too good a nutritional condition when we enter spring. Therefore, we should ideally use the winter to slim them down so that they are at a normal weight before spring arrives, which will help them better tolerate the grass," explains Susan Helany.
Read also: Welfare: How wild should horses be?
There are several advantages to having a lean horse when it is released onto the grass, and we can thus try to avoid, for example, metabolic laminitis, where the horse cannot regulate insulin on its own. "Fat deposits are biologically active tissue, so they affect hormone balance, and that's why we have to be careful with sugar. We simply have an altered hormone balance in the overweight horse, making them particularly vulnerable to sugar," explains Susan Helany and continues:
"When we have an overweight horse, which potentially has insulin resistance, the body will detect sugar in the bloodstream. It needs to be transported into the cells, so the pancreas releases insulin. Insulin will try to unlock the cells to transport the sugar inside, but when it doesn't succeed, the body thinks it needs more insulin. So more insulin is released, and it is this increased release of insulin that plays a huge role in conditions such as laminitis."
In cases of obesity, it is also seen that adipose tissue releases a larger amount of the satiety hormone, leptin. Just like insulin, cells can become resistant to signals from leptin, which can cause a poor sense of satiety, leading the horse to feel hungrier and eat more.
It's important to emphasize that a healthy and fit horse that is kept active will not necessarily experience problems with the sugar in spring and summer grass – or sugar during autumn and winter. It is, of course, always important to be aware of – and all horses can develop laminitis – if you have a coldblood horse in too good of a feeding condition, you should be more attentive to it than your thoroughbred horse, which is slimmer. Regardless of the type of horse you have, you should be mindful that your horse doesn't overeat.
"Something we also see – which is serious and not directly related to sugar – is that the horse overeats. This is about the amount of grass the horse eats in too short a time. This can lead to fermentation colic, which is also serious, but what we often see in spring is laminitis – and all that comes with it," explains Susan Helany.
If your horse, over a longer period – perhaps even over several years – has had a too high energy intake through roughage as well as concentrate feed and grass, and is not regularly exercised, you may end up with a horse that is simply overweight. The excess weight can affect the horse's ability to process sugar intake.
"Sugar has also been a problem for the wild horse if it entered spring and summer overweight. Throughout the winter, there would have been little food, so the horse entering spring and summer slim – perhaps slightly underweight – will better tolerate spring grass and sugar content," explains Susan Helany.
Read also: Put your thin horse back in good shape
As horse owners, we can never be completely sure, as the sugar and nutrient content in grass not only changes from year to year but almost from hour to hour.
"Horses today can tolerate sugar to some extent, and there are so many aspects. For example, we know that obesity is a huge risk factor, but there are also differences between breeds. There are some breeds we see more often than others, so genetics probably play a role, but this is something we learn more about the more research is done," says Susan Helany and continues:
"Right after hard training, the horse's tolerance for sugar will be better, but the horse's digestive system is developed primarily to work with fibers. That's also why roughage is important. It contributes these digestible fibers, and sugar is a minor component. All plants contain sugar, and thus it becomes part of the package when we provide the horse with the digestible fibers from roughage," explains Susan Helany, stressing that the most important advice is for horse owners to consider the specific horse they are dealing with.
The amount of grass and short versus long grass from Susan Helany: I understand that it's a discussion that keeps coming up. In short grass, the percentage of sugar is generally higher, so the proportion of sugar is greater, but the horse can eat less grass because there's not as much grass as when it's in long grass. With long grass, the sugar percentage is generally lower than in short grass, but there is more grass for the horse to eat. Thus, the horse can consume more feed units on long grass than on short grass due to the difference in the amount ingested. Therefore, it's not only the sugar intake but also the amount of energy (feed units) the horse can consume that is crucial.
Susan has extensive professional knowledge about natural horse feeding. Like everyone else at Nordic Horse, she has a holistic approach to horse training and feeding. Susan originally trained as a PBA in Global Nutrition and Health and has worked with dietary supplements, herbs, and minerals for humans for several years. Since 2019, she has transferred this knowledge to horses through education from Dr. Eleanor Kellon, Equinology, and others. With her eye for detail, her goal is for the horse to become more beautiful and healthier with age through proper management and feeding.
