At last spring is here, the days are getting longer, it is getting a little warmer and we are seeing some green grass growth. But in some horses, that lovely new grass seems to cause all sorts of behavioural problems just as we are starting to get going at the start of the new season.
At the first shows and events, or on our hacks out in the spring, some riders report their horses are anxious, reactive, spooky and unpredictable. Is this just because they haven’t had as much ridden work or been out to different places over the winter? Is it because they are getting too much energy than they need? Or is there something else going on in the grass to cause it?
If it is the grass to blame, what is it in grass that results in a spooky horse, an unpredictable pony or just general bad behaviour? And most importantly, how can we manage it?
It is, unfortunately, very hard to prove scientifically what is actually going on, and to prove a definite link between bad behaviour and grass. The behaviour itself can differ daily – people talk about their horses being like ‘Jekyll and Hyde’. However, as there are so many anecdotal reports of horses being completely different after a flush of grass, it is hard not to believe something is going on.
Cause and effect
There are lots of different theories as to what it is in the grass that may be causing these strange signs. One theory is that it is just too much energy being taken in all of a sudden, without the increase in workload to burn it off.
Another theory is that it is due to toxins in the grass, but we haven’t identified what these toxins are, so can’t even begin to test for them or for the effect on the horse. This doesn’t mean they aren’t there – but there is no evidence at present. The only toxin we can easily test for is lolitrem B, which is at least one part of the cause of the condition ryegrass staggers.
Another theory is that the high sugar levels cause a change in the bacteria in the intestines, making it more acidic, and that this causes pain. We definitely get changes in the ‘good’ bacteria in the intestines when we change the diet, and we know that these bacteria are very important in the health of the horse. We are only just finding out all the effects they can have.
However, when this acid overload effect was looked at in laminitis ponies, it was found that even with the grass being much higher than normal in sugar, the ponies would need to eat a very large amount to get this acidic change – so it has not been proven yet that this is a cause.
Another more recent theory is that the high sugar levels in the new grass cause high insulin levels in the blood, which in turn somehow leads to different behaviour. Studies in rats have shown that those fed on a Western-type diet (compared to a normal rat diet) were very much more hyperactive and impulsive. A Western diet to a rat could be equivalent to feeding lush grass to a horse, who is designed by nature to have to work for its food and eat rough grass.
This research is aimed at looking at hyperactivity and other behavioural problems in children, so there is a long way to go before we know really what is going in with our horses in the spring, but the description of hyperactivity and impulsivity could certainly be applied to some of the horses we know who seem to be reacting rather than thinking and processing.
Safety first
If your horse is having behavioural issues, always keep yourself safe, and get help from a trainer or instructor. You don’t want to have an accident and don’t want bad habits (either your horse’s or your own) to form while you are sorting out any underlying issues.
Management and supplements
For all of these theories, we could potentially keep our horses off the grass altogether at the critical times. There are some owners who do keep their horses boxed or yarded fulltime to avoid the grass, but this is not practical for most of us, and, of course, horses are designed to be outside at pasture (although not on the high sugar grasses that are common these days).
There are many supplements designed to help with either the digestive system or with removing toxins. As we have discussed, it is very difficult to prove anything at the moment, and some people find that one type works for them, but not others, and some find no difference. The bottom line is that it doesn’t really matter how these supplements work, as long as they don’t do any harm. So if you find they make a difference, then by all means keep using them for your horse.
Managing your horse’s access to pasture at certain times of day is certainly worth a try. The key is to avoid grazing when the grass has the highest sugar and starch levels. These are also known as non-structural carbohydrates (NSC) and one main one you will see being discussed is fructans. We do know something about high levels of NSC in grass as it is the same situation to avoid when grazing a horse or pony who is prone to laminitis with equine metabolic syndrome.
If you can keep your horse off pasture at certain times and feed low-NSC hay, or hay that has been soaked for an hour to reduce the sugar levels, then you should see an improvement. It may take a few days for things to settle down, so don’t give up. You can feed a low GI vitamin and mineral balancer with this strategy to ensure complete nutrition.
– Take your horse off grass and feed either hay you know is low-NSC or any hay soaked for 30-60 mins (to reduce the sugar and starch levels) at high risk times or if they are showing the unwanted behaviour.
– Avoid grazing altogether when it is cool at night and sunny in the daytime. When there is sunshine, photosynthesis will take place in the grass to produce energy but it won’t grow that much if it is still cool, so won’t use that energy. Instead, it will store it resulting in high energy levels in the grass.
– If it is warmer overnight, then only graze early in the morning (the grass will grow during the night, using up some energy, and it won’t have had enough sun to make more energy). Avoid grazing in the afternoon and evenings, especially when it is sunny but still quite cool.
– If you are able to plant a paddock in higher fibre, low NSC grasses then that would be ideal for your horses. This, of course, is not possible for everyone.
– Using a grazing muzzle may help for some who will tolerate it, but some horses work out how to eat quite a lot even with a muzzle on, so you will need to monitor your horse.
A word of warning
We do have to be careful that by trying to fix one problem we may be at risk for another. Sudden changes in diet can be a risk factor for colic so it is advisable to keep feeding some hay while they are out at pasture so you are not completely switching from all grass to all hay. This may also reduce the amount of grass they eat and reduce any signs while they are at pasture. Monitor your horse carefully if you take it off grass and yard or box it. Talk with your veterinarian if you have concerns about how to manage your horse.
Summary
The behavioural issues we see in spring in some horses can be really frustrating to deal with. For those of you that are already feeding supplements which seem to be helping then continue, as long as they have no side effects. For those wanting to make some management changes, try avoiding exposure to high sugar pasture first. Ideally, the horse needs to be taken off all grass and fed soaked hay to start with, then you can gradually allow grazing at safe times. Get some help from a trainer with the behaviour at the same time as you don’t want bad habits to form, and most importantly you need to keep safe.
