Laminitis in Horses: Causes, Warning Signs, and Prevention

Author: Elliott Garber, DVM

Laminitis is a painful, potentially crippling failure of the laminae, the interlocking tissues that suspend the coffin bone inside the hoof capsule. When those laminae become inflamed and weaken, the bony column of the leg is no longer held firmly in place, and in severe cases the coffin bone rotates or sinks toward the sole. That severe outcome is called founder. Laminitis is a veterinary emergency: if your horse is suddenly lame in both front feet, standing rocked back on its heels, and reluctant to move, call your veterinarian immediately, because how fast you act changes the outcome.

What laminitis actually is

Inside every hoof, thousands of tiny finger-like laminae interlock, one set growing from the coffin bone (the pedal bone, or distal phalanx) and one set lining the inside of the hoof wall. Together they form the suspension that holds the entire weight of the horse off the ground. When those laminae become inflamed and start to fail, the bond loosens. The Merck Veterinary Manual describes laminitis as the inflammation and separation of the laminae of the hoof, and calls it one of the most important and catastrophic diseases in horses.

Once the laminae lose their grip, the pull of the deep digital flexor tendon can rotate the coffin bone away from the hoof wall, or the bone can sink straight down. This displacement is what owners mean by founder. It compresses the blood vessels and soft tissue beneath the bone, and in the worst cases the tip of the coffin bone can press toward or through the sole. Founder carries a guarded to poor outlook, which is exactly why laminitis is treated as an emergency long before it ever reaches that stage.

Laminitis can affect any foot, but it most often hits both front feet at once, because horses carry roughly 60 percent of their weight on the forehand. A horse can be mildly footsore or so painful it refuses to stand. Understanding the range of causes is the difference between preventing it and reacting to it. It is also worth reading the parent horse care overview alongside this guide.

What causes it: the main triggers

Laminitis is not one disease. It is a shared end point that several very different problems can reach. Knowing which one is threatening your horse tells you how to prevent it.

Endocrine laminitis (EMS and PPID)

Endocrine, or hormone-driven, laminitis is now recognized as the most common form. It is driven by high blood insulin, a condition called insulin dysregulation, and the two disorders behind it are Equine Metabolic Syndrome (EMS) and Pituitary Pars Intermedia Dysfunction (PPID), the disease long known as Cushing’s. According to the Merck Veterinary Manual’s discussion of EMS, hyperinsulinemia is thought to be the predisposing condition that leads to laminitis in these horses.

EMS horses are typically overweight “easy keepers” with regional fat pads, especially a hard, cresty neck. PPID tends to show up in older horses and can cause a long, curly coat that fails to shed, muscle loss over the topline, drinking and urinating more, and repeated bouts of laminitis. A horse can have both at once. Because insulin is the thread that ties these together, any at-risk horse that suddenly turns footsore should raise the question of an endocrine cause, not just a diet slip.

Pasture and grass-associated laminitis

Lush pasture is loaded with nonstructural carbohydrates (NSC), the sugars, starches, and fructans in grass. When a susceptible horse eats a large amount of that sugar, the result is similar to gorging on grain, and it can tip an insulin-dysregulated horse into laminitis. This is why laminitis flares in spring and fall, when cool-season grasses spike in sugar, and why the horse most likely to founder on grass is the overweight or insulin-resistant one, not the hard-working thin one. Grass laminitis is largely endocrine laminitis with a trigger you can see growing in the field.

Grain overload and carbohydrate overload

The classic “grain founder” happens when a horse breaks into the feed room and gorges, or is fed far too much concentrate at once. The flood of starch overwhelms the hindgut, and the fermentation that follows produces lactic acidosis and releases toxins into the bloodstream (endotoxemia), which damages the laminae. Any known grain break-in is a reason to call the vet right away, before the horse looks lame, because the damage begins before the pain shows.

Systemic illness (sepsis-related laminitis)

A serious illness elsewhere in the body can inflame the feet. Retained placenta and uterine infection after foaling, severe colic or colitis, pleuritis, and other conditions that flood the system with inflammation and toxins can all trigger laminitis. This is one reason any sick horse deserves close attention to the feet, and why a good vet checks digital pulses on a horse being treated for something that seems unrelated to the hoof.

Supporting-limb laminitis

When a horse cannot bear weight on one leg, because of a fracture, a severe wound, or a bad infection, it overloads the opposite limb for days or weeks. The constant, uninterrupted pressure starves the laminae of normal blood flow and can cause them to fail. This is the form that ended the racehorse Barbaro. It is a known risk whenever a horse is badly lame on one leg, and it is another reason non-weight-bearing lameness is always a veterinary matter.

Warning signs: what laminitis looks like

Laminitis can come on over hours. The earlier you catch it, the better the outcome, so learn the signs and check for them the moment something seems off.

• Lameness, worst on hard ground and on turns. A short, stiff, “walking on eggshells” gait, often in both front feet. The horse may be very reluctant to pick up a foot, because that loads the other one.
• The rocked-back stance. To take weight off painful front feet, the horse plants its front legs out in front and shifts its hindquarters underneath itself, leaning back onto its heels. This classic posture is one of the most recognizable signs.
• Reluctance or refusal to move. The horse plants itself, shifts weight foot to foot, or in severe cases lies down and will not get up.
• Heat in the hoof. The hoof wall and coronary band may feel noticeably warm to the touch.
• A strong, bounding digital pulse. This is the single most useful hands-on sign. The digital pulse runs over the back of the fetlock and down the pastern. Normally you can barely feel it. A strong, throbbing, easy-to-find pulse, especially in both front feet, points strongly to laminitis. It is worth learning to find this pulse on your healthy horse now, so you recognize an abnormal one later.

Any combination of these means call your veterinarian the same hour. Do not walk the horse for exercise, do not wait to “see if it passes,” and do not reach for medications on your own. Pain relief and the correct plan are the vet’s job, and some over-the-counter approaches can mask signs or complicate the diagnosis. While you wait, move the horse the shortest possible distance to soft footing (deep sand or shavings) and keep it quiet.

Why it is an emergency

Laminitis is time-sensitive in a way most lameness is not. The laminae can begin to fail within hours of the trigger, and once the coffin bone starts to move, that displacement does not reverse. Early veterinary care aims to stop the process, control pain, address the underlying cause, and support the foot before rotation occurs. A horse caught in the first hours has a very different outlook from one that has been “a bit footy for a week.” Treat a suspected laminitis the way you would treat a suspected colic: as a call you make now, not tomorrow.

Prevention: the part you control

Most laminitis is preventable, and prevention lives in day-to-day management rather than in any single product. The University of Georgia equine program frames the core of it simply: obesity is a driving factor in insulin dysregulation, so keeping horses at a healthy weight is central to preventing laminitis.

Manage weight and body condition

Score your horse’s body condition regularly and act early when it climbs. A cresty neck and fat pads over the ribs, tailhead, and shoulders are red flags. Weight loss for an overweight horse should be gradual and vet-guided, never crash starvation, which brings its own dangers. Our body condition scoring guide and healthy weight guide walk through how to assess and track this over time.

Control sugar and starch

Limit access to high-sugar grass and grain for at-risk horses. Practical steps include a well-fitted grazing muzzle (worn continuously enough to matter, since part-day muzzling is often not effective), turnout on a dry lot instead of rich pasture during high-risk seasons, and restricting cool-season grass in spring and fall when sugar peaks. Feed forage-first with low-NSC hay, soaked if your vet recommends it, and keep grain to the minimum the horse actually needs. Store all feed securely so a break-in gorge cannot happen. The feeding guide and hay guide cover how to build a lower-sugar ration.

Use a grazing muzzle or dry lot for at-risk horses

An overweight, cresty, or previously laminitic horse should not be turned out on unrestricted spring grass. A muzzle or a dry lot with measured hay is the everyday tool that keeps these horses safe while still letting them move and socialize. Movement itself helps, because exercise improves insulin sensitivity, but only in a horse whose feet are currently sound.

Manage EMS and PPID with your vet

If your horse fits the at-risk picture, ask your veterinarian about testing insulin and, in older horses, ACTH for PPID. These are diagnosable, manageable conditions, and controlling them is the single most powerful thing you can do to prevent recurring laminitis. Managed horses need ongoing monitoring, and your vet will set the diet, any medication for PPID, and the recheck schedule. This is squarely veterinary territory, not something to self-manage from a forum.

Keep the feet in good shape

Regular, balanced farrier care supports healthy hoof structure and gives you an expert set of eyes on the feet on a schedule. Combine that with your own daily hoof check and you catch heat, an abnormal pulse, or a change in stance early. See the hoof care guide for the routine.

Keeping records that catch it early

Laminitis rewards the owner who notices small changes. A horse that has foundered once is at real risk of doing so again, and endocrine cases need weight, diet, and test results tracked over months and years. Keeping this on paper scattered across notebooks makes patterns easy to miss.

This is where a single profile per horse helps. In Creatures you can log body condition scores, farrier visits, and vet findings as health and medical records on the animal’s profile, and set reminders and upcoming care so a weight recheck or seasonal muzzle-on date does not slip. If you are just getting started, adding an animal and then adding a record takes a couple of minutes and gives you one place to spot the trend before it becomes an emergency.

Frequently asked questions

Can a horse fully recover from laminitis?

It depends on how far it went and how fast it was treated. A mild case caught early, with the trigger removed and the underlying cause managed, can recover well and return to work. Cases that progress to significant coffin bone rotation (founder) carry a much more guarded outlook and may leave lasting changes. Early veterinary care is the biggest factor in the outcome.

How do I find the digital pulse?

Feel along the back of the fetlock and down the pastern with your fingertips, on the inside or outside where the artery runs over the bone. On a healthy foot the pulse is faint and hard to find. Practice on your sound horse so that a strong, bounding pulse later stands out immediately as abnormal.

Is spring grass really that dangerous?

For an overweight or insulin-dysregulated horse, yes. Cool-season grass in spring and fall can spike in sugar and push a susceptible horse into laminitis. A fit horse in healthy condition without a metabolic problem usually grazes without trouble. The risk lives in the individual horse, so know which category yours is in.

My horse already had laminitis once. What now?

Treat it as a lifelong management case. Work with your vet to test for and control EMS or PPID, keep weight down, restrict sugar, and monitor the feet closely, especially in spring and fall. Recurrence is common in horses that are not managed, and largely preventable in horses that are.

Should I ever give pain medication before the vet arrives?

No, not on your own. Reach for the phone, not the medicine cabinet. Some medications can mask the signs the vet needs to see and are dosed differently for different horses. Let your veterinarian decide on pain relief and the treatment plan.

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