Digestion

Laminitis & the Hindgut: Understanding the Digestive Connection

Laminitis affects the feet, but one important pathway begins much earlier in the digestive system. Excess starch and rapidly fermentable pasture carbohydrate can alter hindgut fermentation, while insulin dysregulation creates another major route to laminitis. Understanding which pathway matters to your horse is central to sensible feeding, pasture and risk management.

Written by Ben Nedas Reviewed by Dr Rosemary Waring

Quick answer

What horse owners need to know

Laminitis does not always begin in the gut, but there is an important digestive connection.

In carbohydrate-overload laminitis, excessive starch or other rapidly fermentable carbohydrate reaches the hindgut, where rapid microbial fermentation can lower pH, disrupt bacterial populations and contribute to systemic inflammatory processes.

Pasture can also deliver substantial nonstructural carbohydrate.

However, endocrine dysfunction and hyperinsulinemia are now thought to underlie the majority of laminitis cases, particularly in horses and ponies with equine metabolic syndrome, obesity or insulin dysregulation.

Good prevention therefore means identifying the horse's individual risk: control excessive starch, manage pasture appropriately, avoid obesity and investigate metabolic susceptibility where indicated.

Supporting hindgut health can form part of this strategy, but a horse showing signs of laminitis requires prompt veterinary attention.

Start with the horse

Understanding what you're seeing

What you may notice

Early laminitis can be less dramatic than many owners expect.

You may notice:

• Reluctance to walk forward
• Short, careful steps
• Difficulty turning tightly
• Hesitation on hard ground
• Repeated shifting of weight between feet
• Increased time lying down
• A change in normal stance
• Strong or bounding digital pulses
• Warmer-than-usual feet
• Reluctance to pick up one foot because weight must be transferred onto another
• A horse appearing stiff rather than obviously lame
• Reduced willingness to exercise
• Loss of appetite in more painful cases

Laminitis most commonly affects the front feet but can involve all four feet or, in some circumstances, a single supporting limb.

Do not use the absence of an exaggerated “laminitis stance” as reassurance.

A horse that becomes suddenly footsore or reluctant to move should be assessed promptly, particularly if it has known metabolic or pasture-related risk factors.

Common causes

Laminitis is not a single disease with one cause.

Major pathways include:

• Endocrine-associated laminitis linked with hyperinsulinemia
• Equine metabolic syndrome
• Insulin dysregulation associated with PPID
• Excessive grain or starch intake
• Pasture-associated carbohydrate exposure
• Severe gastrointestinal disease and endotoxemia
• Retained placenta and other systemic inflammatory conditions
• Supporting-limb overload following severe injury to another limb
• Certain toxin exposures

Today, endocrine dysfunction is considered the most common underlying pathway.

That is why an overweight pony repeatedly developing laminitis on spring pasture should not simply be described as having “too much fructan” or “hindgut acidosis.”

The horse may have underlying insulin dysregulation that fundamentally changes its response to pasture carbohydrate.

At the same time, carbohydrate overload remains a genuine digestive pathway to laminitis.

Good management therefore needs to distinguish between metabolic susceptibility, hindgut carbohydrate overload and other systemic causes rather than treating all laminitis as one nutritional problem.

What should you check first?

If you are assessing laminitis risk, look beyond the feet.

1. Has this horse had laminitis before?

Previous laminitis is an important reason for more active ongoing management.

2. Is the horse overweight?

Assess overall Body Condition Score as well as regional fat deposits such as a cresty neck.

3. Is insulin dysregulation possible?

Easy keepers, obese horses and ponies, and animals with previous pasture-associated laminitis deserve particular consideration.

4. Does the horse have PPID?

Older horses with PPID may also have insulin dysregulation and increased laminitis risk.

5. What is happening with pasture?

Rapid spring growth, autumn flushes and changing weather can alter nonstructural carbohydrate intake.

6. How much concentrate is being fed?

Look at both the total amount and the quantity given in each meal.

7. What is the starch and sugar content?

The weight of a feed alone tells you little about its nonstructural-carbohydrate load.

8. Has the diet changed suddenly?

Abrupt increases in grain or rapidly changing pasture can substantially alter digestive exposure.

9. Are there digestive signs too?

Changes in manure, increased gas or other gastrointestinal changes can provide additional information about how the ration is affecting digestion.

10. What are the feet telling you?

Monitor gait, willingness to turn, stance, hoof temperature and digital pulses in a horse considered at risk.

11. Is the horse exercising normally?

Lack of movement, obesity and metabolic status may interact, but exercise recommendations must reflect whether the horse is currently sound.

12. Has professional advice changed?

A horse's management plan may need to evolve with age, weight, pasture, metabolic testing and previous clinical history.

Feeding & management steps

Laminitis-risk management depends on why the individual horse is at risk.

Useful principles include:

• Identify horses with previous laminitis, obesity, insulin dysregulation, equine metabolic syndrome or PPID
• Work with your veterinarian on appropriate metabolic investigation where indicated
• Control access to high-nonstructural-carbohydrate pasture in susceptible horses
• Monitor body weight and Body Condition Score
• Avoid sudden grain overload
• Avoid unnecessarily large concentrate meals
• Divide required concentrate across smaller meals
• Review the starch and sugar content of the complete ration
• Make feed changes gradually
• Introduce pasture changes carefully
• Remember that grass carbohydrate content changes with season and weather
• Use forage analysis where particularly tight carbohydrate control is required
• Make forage the foundation of the ration while selecting appropriate forage for the individual horse
• Avoid allowing an at-risk horse to become obese
• Keep dental care up to date
• Maintain appropriate regular exercise where the horse is sound and veterinary advice permits it
• Use grazing muzzles or restricted grazing where appropriate
• Provide suitable low-NSC alternative forage when pasture is restricted
• Monitor the feet and digital pulses in horses with known risk
• Seek veterinary advice immediately if signs of laminitis develop

For horses with insulin dysregulation, the aim is not simply to “protect the hindgut.”

Total dietary nonstructural carbohydrate and the resulting insulin response can be central to risk.

For horses receiving concentrate diets, avoiding excessive starch delivery to the hindgut is an additional digestive priority.

Both pathways can matter in the same horse.

When to contact your veterinarian

Laminitis requires prompt veterinary attention.

Contact your veterinarian if your horse develops sudden foot soreness, becomes reluctant to walk or turn, adopts an unusual stance, repeatedly shifts weight between the feet or develops stronger-than-normal digital pulses.

Some horses appear acutely lame while others initially look stiff or reluctant to move.

Do not wait for the classic rocked-back laminitic stance before seeking advice.

A horse with previous laminitis, equine metabolic syndrome, insulin dysregulation, obesity or PPID should also have its pasture and nutritional management reviewed with a veterinarian before problems recur.

If your veterinarian suspects endocrine-associated laminitis, investigation of insulin regulation and underlying metabolic disease can be particularly important.

Laminitis can result in structural damage within the hoof, including movement of the coffin bone in severe cases, so early recognition and management matter.

EquiNectar or any other digestive supplement should never be used as an alternative to veterinary assessment of suspected laminitis.

The digestive connection

Where digestion fits

There is a genuine digestive connection to laminitis — but it applies most directly to particular pathways.

Starch is primarily intended to be digested enzymatically before it reaches the hindgut.

When large quantities escape digestion in the small intestine, the starch becomes substrate for rapid microbial fermentation in the cecum and colon.

This can lead to increased lactic-acid production and a sharp fall in hindgut pH.

The microbial community changes in response. Acid-sensitive organisms are disadvantaged, while acid-tolerant populations become more competitive. Bacterial disruption can also release microbial products that cross a compromised intestinal barrier and contribute to systemic inflammatory processes.

That is the classic carbohydrate-overload pathway connecting digestion with laminitis.

Grass creates a more complex situation.

Cool-season pasture contains nonstructural carbohydrates including sugars, starch and fructans. Their concentration changes with growth, sunlight, temperature and weather.

Some pasture carbohydrate can contribute to hindgut fermentation, while absorbed sugars can also stimulate insulin.

This matters because hyperinsulinemia is now recognized as a major — and probably the most common — pathway leading to laminitis.

The two mechanisms should therefore not be collapsed into one.

For a metabolically susceptible horse, controlling total nonstructural carbohydrate and insulin response can be critical even if the hindgut appears stable.

For horses exposed to large or rapidly changing carbohydrate loads, supporting effective digestion and hindgut stability remains an important additional management principle.

EquiNectar research

What the research tells us about carbohydrate, the hindgut and laminitis

The connection between diet, hindgut fermentation and laminitis is supported by both independent equine science and EquiNectar research.

Veterinary literature describes a clear carbohydrate-overload pathway.

When excessive concentrate or rapidly fermentable carbohydrate is consumed, appreciable amounts of undigested starch can reach the hindgut. Rapid microbial fermentation produces lactic acid, lowers pH and disrupts the normal bacterial community.

EquiNectar research has measured several features directly relevant to this digestive environment.

In 72 Thoroughbred racehorses completing four weeks of supplementation, mean fecal pH increased significantly from 6.20 to 6.40.

At baseline, seven horses were in the study's severe low-pH category. None remained in that category at week four.

The number of horses above the study's normal fecal-pH threshold increased from 8 of 72 to 40 of 72.

Pasture has also been studied directly.

At Redwings Horse Sanctuary, 45 horses and ponies were randomized between spring pasture alone and spring pasture with EquiNectar supplementation.

Both groups experienced substantial changes in their fecal metabolome during six weeks on spring grass, demonstrating how strongly changing pasture can influence the digestive environment.

By week six, the supplemented and control groups had significantly different metabolic profiles, showing that EquiNectar produced an additional measurable effect against this changing dietary background.

Together these studies support an important nutritional principle: what is digested before the hindgut influences what the microbial community subsequently has available to ferment.

They do not demonstrate that EquiNectar prevents laminitis. They demonstrate changes in digestive pathways that are directly relevant to carbohydrate fermentation and hindgut stability.

45 horses Horses and ponies randomized in the spring-pasture study

6.20 → 6.40 Mean fecal pH over four weeks of EquiNectar supplementation

7 → 0 Horses in the severe low-pH category at baseline → after four weeks

What this research does — and doesn't — tell us

No EquiNectar study has yet measured laminitis incidence as a primary clinical endpoint.

That is the principal limitation when discussing EquiNectar specifically in relation to laminitis.

However, the digestive mechanisms themselves are well established.

Independent veterinary science demonstrates that excessive carbohydrate entering the hindgut can cause rapid fermentation, lactic-acid production, falling pH, bacterial disruption and release of microbial products associated with systemic inflammatory responses.

EquiNectar research addresses several earlier steps in this same pathway.

Supplementation has been associated with reduced fecal acidity in high-concentrate-fed racehorses, altered fecal microbial and metabolomic profiles, changes in fermentation products and a different metabolic response during a randomized spring-pasture study.

These are meaningful digestive outcomes because they reflect changes in the substrate and microbial fermentation environment of the hindgut.

The important distinction is the type of laminitis being discussed.

Carbohydrate-overload laminitis has a clear hindgut component. By contrast, endocrinopathic laminitis associated with hyperinsulinemia is now considered the most common form of laminitis and cannot simply be explained as a consequence of hindgut acidosis.

EquiNectar has not been demonstrated to correct insulin dysregulation, treat equine metabolic syndrome or prevent endocrinopathic laminitis.

Its evidence supports a role in digestive and hindgut management — not replacement of appropriate metabolic, pasture, farriery or veterinary management.

Where EquiNectar fits

Supporting digestion as part of good management

EquiNectar's relevance to laminitis is through digestion — specifically the amount and type of carbohydrate that reaches the hindgut.

Its Enzyme Rich Malt Extract naturally provides digestive enzyme activities including amylase and fructanase, alongside cellulase, xylanase, beta-glucanase, protease, lipase and phytase.

The principle is upstream digestion.

When starch is digested effectively before reaching the hindgut, less undigested starch is available for rapid microbial fermentation in the cecum and colon.

That matters because carbohydrate-overload laminitis has a well-established hindgut pathway. Excessive rapidly fermentable carbohydrate can lower hindgut pH, favor acid-tolerant microbial populations and contribute to microbial disruption and release of bacterial products into the circulation.

EquiNectar research demonstrates that supplementation can measurably alter this downstream fermentation environment.

In Thoroughbred racehorses maintained on their normal high-concentrate diets, mean fecal pH increased from 6.20 to 6.40 over four weeks. Seven horses began in the study's severe low-pH category and none remained in that category at week four.

A separate randomized study of 45 horses and ponies demonstrated that spring pasture substantially altered the fecal metabolome, while horses receiving EquiNectar had a significantly different metabolic response from untreated controls.

These findings provide a strong digestive rationale for supporting upstream digestion where hindgut carbohydrate fermentation is a concern.

They do not mean that EquiNectar treats laminitis.

Endocrine and insulin-related laminitis requires specific veterinary, dietary and pasture management, and these measures remain essential even when digestive support is used.

Explore EquiNectar

Common questions

Frequently asked questions

Can gut problems cause laminitis in horses?

Some forms of laminitis have a clear gastrointestinal pathway, but not all laminitis begins in the gut. When excessive starch or other rapidly fermentable carbohydrate reaches the hindgut, microbes ferment it rapidly. This can lower pH, disrupt the microbial population and contribute to release of bacterial products associated with systemic inflammation. This carbohydrate-overload pathway is well established. However, endocrine dysfunction and hyperinsulinemia are now considered the most common underlying factors in laminitis. The individual horse therefore needs to be assessed rather than assuming every case is caused by hindgut acidosis.

Can too much grain cause laminitis?

Yes. A sudden grain overload is a classic trigger for carbohydrate-overload laminitis. When more starch is consumed than can be digested effectively before the hindgut, substantial amounts can reach the cecum and colon. Rapid microbial fermentation then produces acids, lowers hindgut pH and disrupts the normal microbial ecosystem. This is one reason large grain meals and sudden increases in concentrate intake should be avoided.

Can spring grass cause laminitis?

Pasture can contribute to laminitis risk, particularly in susceptible horses. Cool-season grasses contain nonstructural carbohydrates including sugars, starch and fructans. Their concentrations can change considerably with season, sunlight, temperature and plant growth. Horses with insulin dysregulation, equine metabolic syndrome, obesity or previous pasture-associated laminitis can be particularly vulnerable. For these horses, pasture intake may need to be actively controlled rather than relying simply on gradual adaptation to grass.

What horses are most at risk of pasture-associated laminitis?

Horses and ponies with insulin dysregulation are particularly important to identify. Risk is increased in animals with equine metabolic syndrome, obesity, a history of laminitis and many horses with PPID that also have insulin dysregulation. Ponies and easy keepers are often particularly susceptible. A horse with previous laminitis should have an individualized pasture and nutritional management plan developed with its veterinarian.

Does hindgut acidosis mean a horse will get laminitis?

No. A more acidic and unstable hindgut environment is relevant to the carbohydrate-overload pathway, but it does not mean an individual horse will inevitably develop laminitis. Laminitis has several distinct causes and pathways. Fecal pH can also provide information about changes in the digestive fermentation environment, but it is not a diagnostic test for laminitis or a direct measurement of cecal pH.

Can EquiNectar help reduce digestive risk associated with laminitis?

EquiNectar is not a treatment for laminitis and has not been tested in a clinical trial measuring laminitis incidence. Its relevance is to an important digestive pathway. EquiNectar supports the breakdown of dietary carbohydrate earlier in digestion, changing the substrate subsequently available to the hindgut microbiome. Research has demonstrated measurable changes in fecal pH, microbial activity and fermentation metabolites during supplementation. This makes EquiNectar particularly relevant to nutritional strategies aimed at reducing unnecessary hindgut carbohydrate fermentation, but it does not replace pasture restriction, metabolic investigation or veterinary management in horses at risk of laminitis.

What horse owners need to know

Understanding what you're seeing

Where digestion fits

What the research tells us about carbohydrate, the hindgut and laminitis

Supporting digestion as part of good management

Frequently asked questions

Related horse health guides

Hindgut Acidosis in Horses: Signs, Causes & Management

How Pasture Changes Impact Horses: Spring Grass & Digestion

How to Help Prevent Colic in Horses: Feeding & Management

Gas & Bloating in Horses: Causes & What to Check

Horse Losing Weight or Condition: Causes & What to Check