Quick Answer: What Causes Laminitis in Horses?
The most common cause of laminitis in modern horses is not grain overload or a single dietary mistake. Most laminitis cases seen today are associated with insulin dysregulation, a hormonal disorder commonly caused by Equine Metabolic Syndrome (EMS), Pituitary Pars Intermedia Dysfunction (PPID or Cushing’s Disease), or both.
When insulin levels remain elevated, damage can occur within the laminae—the structures that suspend the coffin bone inside the hoof. This damage can lead to pain, lameness, and in severe cases, rotation or sinking of the coffin bone.
Because of this, successful treatment of laminitis requires treating both the feet and the underlying metabolic disease.
What Is Laminitis?
Laminitis is inflammation and damage of the laminae, the microscopic structures that connect the hoof wall to the coffin bone.
These structures act like thousands of tiny interlocking fingers that hold the coffin bone securely within the hoof capsule. When they become damaged, the attachment weakens.
In severe cases, the coffin bone can rotate or sink within the hoof. This process is commonly referred to as founder.
Laminitis is one of the most painful conditions affecting horses and should always be treated as a medical emergency.
Early Warning Signs of Laminitis
Early diagnosis significantly improves outcomes.
Contact your veterinarian if your horse develops any of the following:
- Reluctance to walk or turn
- Shortened or stiff stride
- Increased digital pulses
- Warm feet
- Frequent weight shifting
- Standing with front feet stretched out in front of the body
- Increased time spent lying down
- Walking as though on eggshells
- Sudden soreness after pasture turnout
- Recurrent episodes of foot soreness
Many horses appear only mildly uncomfortable during the early stages of disease.
Why Most Horses Develop Laminitis
For decades, laminitis was often viewed as a hoof problem.
Today we understand that many cases are actually endocrine diseases that happen to affect the feet.
Research has shown that elevated insulin concentrations can directly damage the laminae. This form of disease is known as endocrinopathic laminitis and is now recognized as the most common form of laminitis in many equine populations.
The two primary causes of insulin dysregulation are:
- Equine Metabolic Syndrome (EMS)
- Pituitary Pars Intermedia Dysfunction (PPID)
Equine Metabolic Syndrome (EMS)
EMS is a hormonal disorder characterized by insulin dysregulation.
Common signs include:
- Easy keeper body type
- Generalized obesity
- Cresty neck
- Fat deposits behind the shoulders
- Fat accumulation around the tailhead
- Difficulty losing weight
- Recurrent laminitis
One of the most common misconceptions we encounter is that obesity causes EMS.
In reality, excess body condition is often evidence that EMS is already present. Obesity is a clinical sign of the disease rather than the cause of it.
Many horses have abnormal insulin levels months or years before developing their first laminitis episode.
PPID (Cushing’s Disease)
PPID is a hormonal disorder that most commonly affects older horses.
Signs may include:
- Delayed shedding
- Long or curly hair coat
- Muscle loss
- Pot-bellied appearance
- Increased drinking and urination
- Recurrent infections
- Reduced performance
- Laminitis
Not every horse with PPID develops laminitis. However, PPID frequently contributes to insulin dysregulation, significantly increasing laminitis risk.
Many affected horses have both PPID and EMS simultaneously.
Why Testing Matters
Treating the feet alone rarely prevents future episodes.
Whenever possible, identifying the underlying cause should be part of the diagnostic plan.
Testing commonly includes:
- Resting insulin concentration
- ACTH testing for PPID
- Blood glucose evaluation
- Digital radiographs of the feet
At Iowa Equine, ACTH and insulin testing are performed in-house, allowing us to obtain results quickly and begin treatment decisions without waiting on outside laboratories.
Radiographs are equally important because they allow us to determine whether coffin bone rotation or sinking has occurred and help guide both medical treatment and farrier recommendations.
Treatment of Laminitis
Treatment depends on severity but may include:
- Pain management
- Anti-inflammatory medications
- Hoof support
- Therapeutic farriery
- Dietary modification
- Management of EMS
- Treatment of PPID when indicated
- Follow-up radiographs to monitor progress
The earlier treatment begins, the better the long-term prognosis.
Preventing Future Episodes
Many horses with EMS- or PPID-associated laminitis can live comfortable and productive lives when properly managed.
Long-term prevention often includes:
- Maintaining an appropriate body condition score
- Feeding low non-structural carbohydrate (NSC) diets
- Careful pasture management
- Monitoring insulin levels
- Routine PPID screening in older horses
- Appropriate medical management when indicated
- Ongoing collaboration between veterinarian and farrier
Frequently Asked Questions
Is laminitis the same as founder?
Not exactly. Laminitis refers to inflammation and damage of the laminae. Founder generally refers to the structural changes that occur when the coffin bone rotates or sinks within the hoof.
Can a horse recover from laminitis?
Many horses recover successfully, especially when diagnosed early and when the underlying cause is identified and treated. Prognosis depends largely on the severity of laminar damage and whether coffin bone displacement has occurred.
Can grass cause laminitis?
Grass itself does not directly cause laminitis. However, pasture can contain high concentrations of sugars and starches that trigger excessive insulin responses in horses with EMS or PPID, increasing their risk of developing laminitis.
What breeds are most commonly affected?
Ponies, Morgans, Arabians, Quarter Horses, miniature horses, and many draft breeds appear predisposed to insulin dysregulation and endocrinopathic laminitis. However, any horse can develop the condition.
Should my horse be tested for EMS or PPID after a laminitis episode?
In most cases, yes. Identifying and treating the underlying metabolic disorder is often the most important step in preventing future episodes.
Iowa Equine’s Approach to Laminitis
At Iowa Equine, we commonly diagnose and manage EMS- and PPID-associated laminitis in horses throughout Iowa and the surrounding Midwest.
Our goal is not simply to manage the painful episode occurring today. We work to identify the underlying disease process driving the laminitis so that a long-term prevention strategy can be developed. Through metabolic testing, digital radiography, nutritional guidance, and collaboration with your farrier, we help horse owners make informed decisions that support long-term hoof health and comfort.
If your horse is showing signs of laminitis, prompt veterinary evaluation is important. Early diagnosis and treatment can significantly improve long-term outcomes.
