Spring Grass, Sugar & Laminitis: What Horse Owners Need to Know

For many horse owners, the arrival of spring is one of the best times of the year. Paddocks begin to green up, the days become longer and horses often have access to considerably more fresh pasture than they did through winter.

However, that change in pasture can also change the nutritional profile of your horse's entire diet.

In our previous article, Spring Dietary Changes for Horses: What Every Horse Owner Should Know, we looked at the broader changes horse owners should consider as we move from winter into spring, including pasture management, adjusting hard feeds, monitoring weight and watching for laminitis.

In this article, we're taking a closer look at one particularly important part of that transition: spring grass, dietary sugars and the horses that may need a little extra management as the paddocks begin to grow.

Why Does Spring Grass Need to Be Managed?

Fresh pasture is an excellent feed for horses. It provides fibre, energy, protein, vitamins and other nutrients, while grazing also allows horses to express natural feeding behaviours.

The problem isn't that fresh grass is inherently "bad" for horses.

The issue is that pasture can change surprisingly quickly. As environmental conditions, temperature, sunlight and plant growth change, so can the amount of energy and non-structural carbohydrates (NSC) that the horse consumes.

NSC is a broad nutritional term that includes sugars and starches, along with certain other readily available carbohydrates in forage.

Periods of rapid pasture growth have long been associated with pasture-related laminitis, particularly in susceptible horses. Horses with obesity or insulin dysregulation can be especially vulnerable to high-carbohydrate pasture.

For many healthy horses, access to spring pasture is unlikely to cause a problem when it is introduced sensibly and their overall diet remains appropriate. For an easy keeper or a horse with a history of laminitis, Equine Metabolic Syndrome (EMS), insulin dysregulation or PPID, however, the same paddock may require much more careful management.

Sugar Isn't the Whole Story – Insulin Matters Too

We often hear horse owners talk about avoiding "sugary grass", but the relationship between pasture and laminitis is more complicated than simply the amount of sugar in a blade of grass.

One of the most important factors is how the individual horse responds to carbohydrates.

Insulin dysregulation occurs when the horse has an abnormal insulin response to dietary carbohydrates. It is a defining feature of Equine Metabolic Syndrome and is strongly associated with an increased risk of laminitis. PPID can also occur alongside insulin dysregulation, particularly in older horses.

This is why two horses grazing the same paddock can have very different outcomes.

One may maintain a healthy body condition and have no problems at all, while another may gain weight rapidly or be at increased risk of laminitis.

It is important to manage the horse in front of you, rather than assuming that one grazing strategy will suit every horse.

Don't Rely Solely on the Time of Day

Traditional advice has often suggested grazing susceptible horses in the early morning because pasture sugar concentrations generally rise through the day and fall overnight.

There is some basis for this advice, but pasture carbohydrate concentrations are influenced by several factors, including weather, plant species, temperature and growing conditions. They can therefore fluctuate substantially.

For a horse at particularly high risk of laminitis, simply changing turnout from afternoon to morning should not be considered a complete management strategy.

Restricted pasture intake, appropriate low-NSC forage and veterinary assessment of insulin regulation may be much more important.

Watch Your Horse's Body Condition

Spring pasture doesn't just influence laminitis risk – it can also provide considerably more energy than some horses require.

An easy keeper may gain weight despite receiving very little hard feed.

Don't rely entirely on what the scales – or weight tape – tell you. Look at where fat is accumulating.

Regularly assess:

• the ribs

• the crest of the neck

• behind the shoulders

• along the back

• around the tail head.

Taking a side-on photograph of your horse every few weeks can also make gradual changes much easier to recognise.

Obesity itself is an important risk factor for metabolic problems and is associated with an increased risk of laminitis.

If your horse begins gaining unnecessary weight, don't wait until the end of spring to make changes.

Does Your Horse Still Need the Same Hard Feed?

This is one of the easiest dietary adjustments to overlook.

A ration that was perfectly appropriate during winter may provide too much energy once good-quality pasture becomes available.

Rather than simply adding spring grass on top of the existing ration, reassess the entire diet.

Ask yourself:

Has my horse's workload changed?

Has their body condition changed?

How much pasture are they now consuming?

Do they still require the same quantity of concentrate feed?

Reducing a concentrate doesn't necessarily mean removing all supplementary feeding. A horse may still require additional vitamins, minerals, protein or other nutrients even when their energy requirements are largely being met by pasture.

Depending on the individual horse, a suitable ration balancer, concentrated vitamin and mineral supplement, or appropriate low-intake feed may allow you to provide those nutrients without unnecessarily adding large amounts of calories, sugar or starch.

Grazing Muzzles Can Be a Useful Tool

For horses that need pasture restriction but still benefit from turnout, a properly fitted grazing muzzle can be useful.

Rather than completely removing the horse from pasture, the muzzle limits how much grass the horse can consume while still allowing turnout and grazing behaviour.

Interestingly, research published in 2026 involving horses with insulin dysregulation found that horses wearing grazing muzzles while on pasture had significantly lower insulin responses than horses grazing without them under the conditions studied. The researchers concluded that grazing muzzles may therefore be a useful management strategy, while emphasising that pasture composition and individual responses can vary.

A grazing muzzle must be fitted correctly, checked regularly and allow the horse to drink comfortably.

Remember that a muzzle is a management tool, not a guarantee that unlimited access to every pasture will be safe for a metabolically vulnerable horse.

Hay May Still Have an Important Role

It can seem strange to feed hay when there is green grass everywhere, but hay can still be useful during spring.

Providing a known forage source can help maintain consistency when pasture availability changes and can form part of a controlled grazing program.

For horses with insulin dysregulation or a history of laminitis, forage selection becomes particularly important. Current veterinary recommendations generally focus on restricting high-NSC feeds and, where required, feeding appropriately tested low-NSC forage.

If sugar content is critical for your horse, laboratory forage analysis is far more reliable than attempting to determine sugar levels by looking at, smelling or feeling the hay.

Know the Early Signs of Laminitis

Early intervention is extremely important.

Signs can range from subtle changes in movement through to obvious severe lameness.

Keep an eye out for:

• reluctance to walk or turn

• shortened or pottery steps

• shifting weight between the feet

• increased heat in the hooves

• a stronger-than-normal digital pulse

• reluctance to move on firm surfaces

• an unusual stance intended to unload painful feet.

If you suspect laminitis, contact your veterinarian promptly. Laminitis can cause serious and potentially permanent damage to structures within the hoof and should not simply be managed by removing the horse from grass and "waiting to see".

Which Horses Need Extra Attention This Spring?

While every horse should have its body condition and diet monitored, particular care may be required for horses and ponies that:

• are overweight or gain weight easily

• have a cresty neck or regional fat deposits

• have previously suffered laminitis

• have diagnosed or suspected insulin dysregulation

• have Equine Metabolic Syndrome

• have PPID, particularly where insulin dysregulation is also present

• require very few calories to maintain condition.

A horse doesn't necessarily have to look obese to have insulin dysregulation, so previous history and veterinary testing can also be important.

Spring Feeding Is About Balance

The arrival of green pasture doesn't mean horse owners need to fear grass.

For most horses, good pasture can form an extremely valuable part of a healthy, forage-based diet.

The goal is simply to recognise that spring changes the diet, even if you haven't changed anything in the feed bin.

Monitor pasture access, reassess hard feed, keep an eye on body condition and pay particular attention to horses that are prone to weight gain or metabolic problems.

As we discussed in our earlier article, Spring Dietary Changes for Horses: What Every Horse Owner Should Know, seasonal changes are a good opportunity to review your horse's entire feeding program rather than continuing the same ration year-round.

If you're unsure whether your horse's current feed is suitable as the spring pasture comes through, come in and chat with the team at Oakford Stockfeeds. We can help you look at your current feeding program and the feed options available to suit your horse's individual needs.

For horses with a history of laminitis, insulin dysregulation, EMS, PPID or other medical conditions, dietary changes should be discussed with your veterinarian or suitably qualified equine nutrition professional.