Laminitis and Founder in Horses Explained
Laminitis is painful inflammation of the laminae inside the hoof, and founder is its advanced form. Learn the causes, warning signs, and why it is an emergency.
Quick definition: Laminitis is inflammation and failure of the laminae, the tissues that bond the hoof wall to the coffin bone inside the foot. When the bond weakens, the coffin bone can rotate or sink, which owners call founder. It is intensely painful and always treated as a veterinary emergency. In senior horses, most laminitis is endocrine, driven by high insulin from EMS or PPID.
Laminitis is one of the most feared words in the horse world, and for good reason. It is painful, it can be permanently damaging, and in senior horses it often arrives quietly through a metabolic problem the owner did not know was there. Understanding it is the first step to preventing it.
The key idea is mechanical. Inside the hoof, thousands of interlocking laminae act like Velcro, suspending the coffin bone from the hoof wall. When those laminae become inflamed and fail, that suspension gives way, and the bone can rotate or drop. That is why laminitis is both so painful and so serious.
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Laminitis Versus Founder
The two words are often used interchangeably, but there is a useful distinction. Laminitis is the disease process: the inflammation and weakening of the laminae. Founder is the older term for the structural result, when those laminae fail and the coffin bone rotates downward or sinks within the hoof. Put simply, severe or untreated laminitis can lead to founder.
The Three Causes
Veterinarians group laminitis by its trigger, and the category matters because it points to prevention.
| Type | Trigger |
|---|---|
| Endocrine | High insulin from EMS or PPID; the most common type in seniors |
| Inflammatory / sepsis | Grain overload, retained placenta, severe colic or infection |
| Supporting-limb | Overloading one leg to spare a serious injury in the other |
For older horses, the endocrine form is overwhelmingly the most common. That is why PPID and EMS are so closely tied to laminitis, and why controlling insulin is central to prevention.
Warning Signs to Know
- A short, stilted, walking-on-eggshells gait, worst when turning on hard ground.
- Rocking weight back onto the heels to take pressure off the painful toes.
- Heat in the hoof walls and a strong, bounding digital pulse at the back of the pastern.
- Lying down more than usual or being reluctant to move.
- Shifting weight from one foot to another while standing.
Knowing your horse's normal digital pulse and hoof temperature at rest makes these changes much easier to catch early.
Why It Is Always an Emergency
Laminitis can progress within hours, and once the coffin bone rotates the damage may be permanent. If you suspect it, call your veterinarian right away. While you wait, keep the horse on soft footing or deep bedding, move it as little as possible, and remove all grass and grain. Do not force the horse to walk to a different location unless your vet directs it.
Prevention in Senior Horses
Because most senior laminitis is metabolic, prevention means managing the root cause. Test for and treat PPID and EMS, keep dietary NSC low, hold body weight to a healthy Henneke score, restrict lush or high-sugar pasture, and keep a steady farrier schedule. For the clinical and hoof-care detail, see laminitis in senior horses and laminitis hoof management.
This page is educational and does not replace your veterinarian. Laminitis is a true emergency, and any suspected case needs immediate professional care.
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Frequently Asked Questions
What is laminitis in horses?
Laminitis is inflammation and failure of the laminae, the interlocking tissues that bond the hoof wall to the coffin bone inside the foot. When these laminae weaken, the bond can stretch or tear, allowing the coffin bone to rotate or sink. It is intensely painful and is one of the most serious conditions in horses, second only to colic as a cause of suffering and loss in many surveys.
What is the difference between laminitis and founder?
Laminitis refers to the inflammation and damage in the laminae. Founder is the older, common term for the more advanced stage, where the laminae fail and the coffin bone rotates or sinks within the hoof. In everyday use the words overlap, but technically laminitis is the disease process and founder describes the structural collapse that can result if laminitis is severe or untreated.
What causes laminitis?
There are three broad causes. Endocrine laminitis, the most common, is driven by high insulin from EMS or PPID. Inflammatory or sepsis-related laminitis follows illnesses like grain overload, retained placenta, or severe infection. Mechanical or supporting-limb laminitis develops when a horse overloads one leg to spare an injured one. In senior horses, the endocrine type tied to metabolic disease is by far the most frequent.
What are the warning signs of laminitis?
Look for a reluctant, walking-on-eggshells gait, especially turning on hard ground, and a horse rocking its weight back onto the heels to spare the toes. Other signs are heat in the hoof walls, a strong bounding pulse felt at the back of the pastern, lying down more than usual, and shifting weight from foot to foot. Front feet are most often affected, but any or all feet can be involved.
Is laminitis an emergency?
Yes. Treat any suspected laminitis as an emergency and call your veterinarian immediately. The first hours matter because damage to the laminae can progress quickly, and early intervention gives the best chance of preventing coffin bone rotation. While waiting, move the horse as little as possible, keep it on soft footing or deep bedding, and remove access to grass and grain. Do not force the horse to walk.
Can a horse recover from laminitis?
Many horses recover and return to comfort, but the outcome depends on severity, how fast it was treated, and how well the underlying cause is controlled. Mild cases caught early often do well. Cases with significant coffin bone rotation need long-term farrier and veterinary management and may have lasting limitations. Preventing the next episode by controlling insulin, diet, and weight is central to recovery.
How is laminitis prevented in senior horses?
Prevention focuses on the metabolic causes. Test for and manage PPID and EMS, keep dietary sugar and starch low, control body weight to a healthy Henneke score, restrict access to lush or high-sugar pasture, and keep up regular farrier care. Knowing your horse's digital pulse and hoof temperature at rest helps you spot trouble early. Catching insulin problems before founder is the best protection.
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