Laminitis Caused by Insulin Dysregulation (Insulin Resistance)
Laminitis is one of the most painful and devastating diseases affecting horses. Although many horse owners associate laminitis with horses eating too much lush grass or grain, we now know that most cases are actually linked to hormonal disease.
Current research estimates that approximately 90% of laminitis cases are endocrinopathic, meaning they are associated with conditions such as:
- Equine Metabolic Syndrome (EMS)
- Pituitary Pars Intermedia Dysfunction (PPID or Cushing’s disease)
Understanding why this form of laminitis occurs is essential because it changes how we manage and treat affected horses.
What Is Insulin Dysregulation?
In a healthy horse, insulin is released after a meal to help move glucose from the bloodstream into body tissues where it can be used or stored.
In horses with insulin dysregulation (sometimes referred to as insulin resistance), the body produces abnormally high levels of insulin following meals.
These prolonged elevations in insulin, known as hyperinsulinaemia, are now recognised as the primary trigger for endocrinopathic laminitis.
Importantly, it is the high insulin concentrations, rather than high blood glucose alone, that damage the laminae within the hoof.
Is Endocrine Laminitis an Inflammatory Disease?
One of the biggest advances in laminitis research over the past decade is our understanding that endocrinopathic laminitis develops differently from laminitis caused by grain overload or severe illness.
Traditional inflammatory laminitis, such as that associated with sepsis or carbohydrate overload, involves widespread inflammation throughout the body.
In contrast, horses with insulin-associated laminitis generally do not show the same inflammatory pathways that occur in sepsis-related laminitis.
Studies have demonstrated little evidence that inflammatory cytokines play a major role during the early stages of insulin-induced laminitis.
This helps explain why simply treating inflammation does not address the underlying cause.
Why Doesn’t “Bute” Cure It?
Non-steroidal anti-inflammatory drugs (NSAIDs), such as phenylbutazone (“Bute”), remain extremely important for pain management.
However, they do not treat the underlying hormonal disorder responsible for endocrinopathic laminitis.
Successful treatment requires controlling the horse’s insulin concentrations while simultaneously managing pain, providing appropriate hoof support and correcting the underlying endocrine disease.
Does Grain Cause Insulin Resistance?
This is another common misconception.
Grain does not directly cause insulin dysregulation.
However, feeds high in starch and simple sugars can produce large insulin responses, making them unsuitable for horses already affected by Equine Metabolic Syndrome or PPID.
Many modern high-fibre feeds and grain co-products actually contain considerably less starch than traditional cereal grains and may be appropriate when included as part of a carefully balanced diet.
The focus should always be on the overall starch and sugar content of the total diet, rather than simply whether a feed contains grain.
Nutritional Management
Nutrition is one of the most important tools available for managing insulin dysregulation and reducing the risk of future laminitis episodes.
Key principles include:
- Remove horses from lush pasture during high-risk periods.
- Feed low-sugar, low-starch forage.
- Soak hay where appropriate to reduce water-soluble carbohydrates.
- Maintain an appropriate body condition score.
- Avoid feeds high in starch and sugar.
- Balance the diet to meet vitamin and mineral requirements.
- Encourage safe weight loss in overweight horses under veterinary guidance.
For many horses, achieving and maintaining a healthy body weight significantly improves insulin regulation.
Supporting Recovery
Once acute pain is controlled, recovery focuses on:
- Corrective farriery or hoof support
- Veterinary monitoring
- Managing PPID where present
- Improving insulin sensitivity through weight management and appropriate exercise once the horse is comfortable
- Providing a balanced diet based on forage analysis where possible
What About Antioxidants?
Oxidative stress may contribute to tissue damage in many diseases, and feeding a balanced diet containing adequate antioxidants is important for overall health.
Nutrients such as:
- Vitamin E
- Vitamin C (where appropriate)
- Selenium (only where deficient)
- Omega-3 fatty acids from marine based or flaxseed sources
may help support normal cellular function as part of an overall nutritional programme.
However, antioxidant supplementation should complement—not replace—the primary goals of controlling insulin concentrations and maintaining appropriate body weight.
What About Herbal Supplements?
A number of herbs are promoted for horses with laminitis because of their antioxidant, anti-inflammatory or circulatory properties.
These include herbs such as:
- Rosehips
- Boswellia
- Ginkgo biloba
- Nettle
- Meadowsweet
- Devil’s claw
- Gynostemma (Jiaogulan)
While some of these herbs contain biologically active compounds and may have traditional or experimental uses, scientific evidence supporting their routine use in horses with laminitis remains limited.
Some herbs may also interact with medications or contain substances prohibited in competition horses.
For this reason, herbal therapies should only be used under the guidance of an appropriately qualified veterinarian or equine herbal practitioner and should never replace evidence-based veterinary treatment.
Laminitis in a Nutshell
Laminitis is a disease affecting the sensitive laminae that suspend the coffin bone within the hoof.
If severe, weakening of these tissues can allow the coffin bone to rotate or sink, causing extreme pain and potentially permanent damage.
Most modern cases are associated with hormonal disorders such as EMS or PPID rather than simple inflammation.
If you suspect laminitis:
- Contact your veterinarian immediately.
- Remove the horse from lush pasture.
- Provide deep, supportive footing such as sand or shavings.
- Feed low-sugar forage.
- Restrict starch and sugar intake.
- Work with your veterinarian, farrier and equine nutritionist to develop a long-term management plan.
The Bottom Line
Endocrinopathic laminitis is no longer viewed as simply a disease caused by “too much grass.”
It is a complex hormonal disorder driven primarily by prolonged elevations in insulin.
Successful management requires more than pain relief. It requires controlling insulin levels, managing body weight, providing appropriate hoof care and feeding a carefully balanced diet tailored to the individual horse.
The earlier insulin dysregulation is recognised and managed, the greater the chance of preventing future laminitis episodes and maintaining long-term hoof health.
Nutrition is the science of prevention.
