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Spring Grass and Laminitis
Springtime can be difficult to navigate as a horse owner. The green grass is just starting to crop up and soon will take over the fields.
The horses are craving it, and with hay prices increasing it’s tempting to just open up the pastures and let the horses have an all-you-can-eat grass buffet. Since food and hooves are intimately connected, here are some tips to make spring a bit simpler. (Note that grass varies greatly across countries, this article is most relevant to the Canadian prairies which are very green in the spring and summer, drought prone in the fall and dead in the winter under a thick layer of snow).
First and foremost, if you are going to be transitioning the horses from hay onto grass, the best way to do so is incrementally. This helps mitigate two issues: Colic and laminitis. As with any change in diet, it’s always best practice to start slow to avoid upset bellies. Allow them to have a couple hours of grazing, increasing it slowly over about a week until they are accustomed to their new forage source. As for the second part, if your horse is starting to show signs of inflammation in their bodies, it will be milder, slower and easier to spot early, if they are transitioned slowly. A horse showing signs of being at risk for laminitis, after switching to grass, should be pulled off the grass immediately. (Once they are stable and grasses mature later in season, they can be trialled again on grass, again slowly and monitored).
What are the signs that things are not going well? We call this stage “subclinical laminitis”, because there are no clinical signs of it but it is likely happening at a very low grade. This is the time to act, before it becomes full blown “clinical” laminitis. Oedema is a major sign. The sheath (or teat area on a mare) will be swollen as it’s a low point on the body. Swollen eyes, sometimes wind puffs on the legs are another area to look at. If a horse is already insulin resistant and has fat pads, the pads will become harder, denser and more swollen. Other signs include slowing down (not running in with the herd but rather choosing to stay behind and walk when that’s not typical, for example), laziness when worked, being more tender than usual on certain surfaces, sore after a trim when that’s not typical (really big symptom), acting stiff and “naughty” during a trim (especially stiff hinds) when atypical for the horse, and laying down more than usual. Of course, if nothing is done, it does become more severe and this is when you get the typical laminitis stance of rocking back, blood presenting in white line of foot and possibly founder if not addressed right away. These signs and symptoms can appear and disappear very quickly in response to management changes. Sometimes overnight.
When considering whether to put a horse on grass in the spring, it’s important to understand their individual risk factors. If the horse has a risk factor, its likelihood of tolerating extra sugary immature spring grass is not good. Think of spring grass as a stressor. If your horse is really healthy, it can likely tolerate a health stressor and bounce back. If it’s already in a poor state, then spring grass might be the straw that breaks the camel’s back. Obesity is an easy one to see, and so are metabolic fat pads in the case of an insulin resistant horse.
Cushing’s is another risk factor. If the horse is fed a daily ration of hard feed/grain, that adds another risk as now the horse will be getting even more sugar and starch in its day. Sedentary horses are more at risk of becoming overweight on grass. Something else to consider, is that vaccines, deworming, and dentals are all done in the spring time and are all little stressors on the body. Think about separating them and doing one at a time, maybe before the grass even comes in. The way I think about it is: A horse who is at “0” (perfectly healthy, no risks) can resist laminitis more easily. The “0” horse may be put in a bad situation and become a “3”, which gives the owner plenty of time to so something about it before it gets to be a “10” (full blown laminitis). A horse who’s at a “5” already, might end up at a 10 overnight when only one added stressor overloads the system.
Another consideration is pasture health. A horse is more at risk on an overgrazed, non-native, “improved” pasture (yes those eaten down ones you see at boarding barns, yes there’s enough grass there to cause
issues) than on an older, native pasture that is managed and not overgrazed. Anything that stresses grass will raise sugar content. Even the dry Canadian autumn is stressful for grass and will again raise sugar content (as well as compounding with seasonal ACTH rises in the horses). Overgrazing is a huge grass stressor, so short grass is not better than long grass. If you have limited pasture and too many horses, consider giving the pasture breaks to grow and mature. Either by limiting total time out there, or strip grazing. Mature summer grazing is always safer than immature spring grazing. Consider the effect of growth stage on mineral balance, and fibre content as well (leafy sprouts vs stemmy mature stalks of grass). Grass species matters too- Ryegrass (and other lawn grasses, dairy cow grasses) is never appropriate for horses. Pastures full of clover are also risky, and especially Alsike clover which is toxic in large amounts.
What are some management ideas to help make spring go by smoothly?
Feeding hay while the grass is still immature doesn’t have to be a hit to the pocketbook, as it will mean more grass to graze on for the winter (flipping the feeding situation around- winter grass and summer hay… note this only applies to countries where the grass truly dies in the winter). Track systems are wonderful alternatives too (look up paddock paradise for ideas). If boarding and have no choice, consider a grazing muzzle. If needing to be on a 12 hour rotation, consider turning out to pasture at night instead of during the day as sugar levels are lower.
You can also alternate between grass and barley straw rather than grass and hay to lower overall calorie intake. As well, check in with your vet and hoofcare provider. As a trimmer, myself, I often am able to notice small signs of impending laminitis before it gets very acute so I make sure to let clients know and they can react accordingly.
Finally, a note to add that grass does have some good vitamins and nutrients in it, so it’s important to understand what a horse will be lacking if it isn’t able to safely graze. The biggest concern is vitamins (notably E and Bs), which can be added to the diet of a hay-only horse.
Klervi Dorfsman NPHCP CEHCA