Reducing the risk of laminitis... by limiting grass intake

01 Jun 2021 (Horse health news)

Limiting grass intake at spring turnout can feel like a difficult challenge, but it is an important way in which you can reduce your horse’s laminitis risk. The growing grass at this time of year is full of sugars, and when digested these are absorbed into our horses’ blood stream causing an insulin spike. Insulin is an important hormone which is responsible for taking sugar out of the blood and into cells of the body. However, if raised too high or for too long insulin can cause laminitis. The risk of laminitis is especially high in horses with Equine Cushing’s disease or Equine Metabolic Syndrome.1

In this article we look at the main different grazing options available to you, which can be used to limit your horse’s grass intake and therefore reduce their risk of an insulin spike and a laminitis episode. Which option you choose will depend on the pastures available to you, as well as your horse’s temperament and laminitis risk level.

The most common grazing strategies are:

1. Strip grazing.  This involves fencing off a strip in your horse’s pasture and moving the fences regularly to allow your horse access to fresh grass as needed. How often you move the fencing will be determined by the grass growth as well as your horse’s appetite so it’s important to monitor your horse and the pasture to see how much grass is eaten each day.  When you are placing the fencing it’s important to ensure the fences are strong enough to stop your horse from jumping out, the strips arewide enough that your horse can easily turn around, and if there is more than one horse in the strip make sure that they can pass each other without getting too close.Bear in mind that you will need to poo pick regularly because of the reduced space.  Strip grazing will limit the amount of grass available to your horse, and will prevent them from selectively grazing the richest grass. It may also restrict their exercise however, and depending on the size of the strip and the sugar level in the grass it may not reduce the amount of grass intake enough to prevent an insulin spike.
2. Perimeter (or track) grazing.  This is similar to strip grazing, but the horses are fenced to the outside perimeter of their field. This encourages them to move around the field more thus increasing their daily steps as well as reducing their grass intake. As with strip grazing it’s important to ensure that your horse cannot jump the fence, that they have sufficient space, and that you poo pick the track regularly.
3. Grazing muzzle.  This is not appropriate for all horses, but in the right circumstances a muzzle can reduce the amount of grass eaten whilst allowing freedom of movement. Some horses tolerate muzzles well, whereas others dislike them. There are many different makes of muzzle that you can try, and it is worth monitoring your horse for the first few days that they wear a muzzle to check for signs of discomfort and ensure they are able to eat and drink.
4. Bare paddock or ménage turn out.  This gives you full control of what your horse is eating, and allows normal levels of exercise if the paddock is large. Some horses may eat sand or dirt in bare paddocks which can lead to impaction colic, and if there is no forage at all in the paddock this can also cause digestive problems. It’s therefore important to monitor your horse’s forage intake whilst on a bare paddock.
5. Graze with sheep.   Sheep or other companions will lower the total amount of grass available, and can also help with parasite control.

A crucial point is not to only reduce turnout time. Horses and ponies learn to binge eat to compensate for the reduced grazing time, and can even eat more than previously!2 Using one of the methods above to restrict the pasture available to your horse is a more effective means of actually reducing their grass intake rather than just reducing turnout time.

Restricting the feed intake of any pet is a difficult undertaking. The principle is simple but in reality it is challenging. The first step is to select the grazing option that you feel most suits your horse, and then to implement this whilst closely monitoring them. If you notice that your horse is employing tactics to increase their grass intake such as pulling a muzzle off or reaching through a fence, or is eating sand from a bare pasture, then you may need to re-think and try something different. It will often take a few tries before you find a method that works well for you and your horse, but it is well worth persevering.

1. De Laat MA, Sillence MN, Reiche DB. Phenotypic, hormonal, and clinical characteristics of equine endocrinopathic laminitis. J Vet Intern Med 2019;33:1456–1463.

2. Ince J, Longland AC, Newbold JC, et al. Changes in proportions of dry matter intakes by ponies with access to pasture and haylage for 3 and 20 hours per day respectively, for six weeks. J Equine Vet Sci 2011;31:283.