Bit & Bridle

Equine Laminitis (Founder)

Other Names

  • Founder — typically used when laminitis has caused rotation or sinking of the coffin bone
  • Road founder — laminitis triggered by excessive work on hard surfaces
  • Grass founder — laminitis caused by ingestion of lush, high-sugar pasture

What is Laminitis in Horses?

Laminitis is one of the most painful and potentially devastating conditions in equine medicine. It is an inflammatory disease affecting the laminae — the interlocking tissues that bond the hoof wall to the pedal (coffin) bone inside the hoof capsule. When these tissues become inflamed, blood flow to the hoof is disrupted, the sensitive laminae weaken, and the coffin bone can rotate downward or sink within the hoof. In the most severe cases, the tip of the coffin bone penetrates the sole of the hoof.

Laminitis can affect any horse at any age, but it is particularly prevalent in ponies, cobs, overweight horses, and horses with metabolic conditions. It most commonly affects the front feet, though all four can be involved. Even a single episode can cause permanent structural changes — which is why early recognition and prompt veterinary intervention are absolutely critical.

The term “founder” specifically describes the mechanical consequence of laminitis: the displacement of the coffin bone. Not all horses that suffer laminitis will founder, but repeated or severe acute episodes significantly increase the risk.

What Causes Laminitis in Horses?

Metabolic Causes

  • Equine Metabolic Syndrome (EMS): Insulin dysregulation is now understood to be the single most common cause of pasture-associated laminitis. When blood insulin spikes — particularly in response to non-structural carbohydrates (NSCs) in grass — it triggers a cascade of events that damages the lamellar tissue.
  • Pituitary Pars Intermedia Dysfunction (PPID/Cushing’s Disease): Horses with PPID have chronically elevated insulin levels and are at significantly higher risk of recurrent laminitis, particularly in autumn when pasture fructan content peaks.
  • Obesity: Excess body weight increases mechanical load on the laminae and is strongly associated with insulin resistance. Fat horses and ponies are far more susceptible than horses in lean condition.

Diet-Related Causes

  • Pasture Laminitis: The most common presentation in the UK. Lush spring and autumn grasses are high in fructans and non-structural carbohydrates, which trigger excessive insulin responses in susceptible horses. Cool, bright mornings — when grass sugar content peaks — are particularly high risk.
  • Grain Overload: Sudden access to large quantities of grain or concentrate feeds causes rapid fermentation in the hindgut, leading to endotoxin release and widespread vascular disruption in the hooves.
  • Feed Changes: Abrupt changes to high-starch feeds without a gradual transition period can precipitate acute laminitis.

Systemic Illness

  • Endotoxaemia: Severe systemic illness, including colic, colitis, retained placenta, or pleuropneumonia, releases endotoxins into the bloodstream that directly damage lamellar vasculature.
  • Strangles: Systemic spread of Streptococcus equi can trigger laminitis as a secondary complication.
  • Fever and Sepsis: Any condition causing high, sustained fever or septicaemia puts horses at risk.

Mechanical Overload

  • Support Limb Laminitis: When a horse bears excessive weight on one leg because of injury to another, the over-loaded limb can develop laminitis. This is a serious concern in horses recovering from fractures or severe lameness.
  • Concussive Laminitis: Prolonged work on very hard surfaces — particularly in unfit horses or those with flat soles — can cause concussive damage to the laminae.

Corticosteroid Administration

In susceptible horses, high doses of systemic corticosteroids can provoke laminitis by inducing insulin resistance. This is a recognised risk in horses with EMS or a prior history of the condition, and veterinarians will always weigh this up carefully before prescribing steroids to at-risk horses.

Signs and Symptoms of Laminitis

Recognising laminitis early can make an enormous difference to outcome. Classic signs include:

  • Lameness: Usually bilateral in the front feet. The horse may appear to “walk on eggshells” or show a stilted, shuffling gait.
  • The “laminitic stance”: The horse shifts weight backward onto the hindquarters to relieve pressure on painful front feet, often leaning back with front legs pushed forward.
  • Reluctance to move: Affected horses are often unwilling to walk and may refuse to lift a foot for picking out.
  • Heat in the hooves: The hooves — particularly in the toe region — feel noticeably hot to the touch.
  • Increased digital pulse: A bounding pulse can be felt at the fetlock (pastern junction), indicating inflammation and increased blood pressure in the hoof.
  • Pain on hoof testers: Pressure applied to the sole — particularly at the toe — causes a marked pain response.
  • Rings on the hoof wall: In chronic cases, abnormal growth rings (wider at the heel than the toe) indicate previous or ongoing laminitic episodes.
  • Sole bruising or dropped sole: A flat or dropped sole suggests coffin bone displacement and is a serious sign requiring urgent attention.

Diagnosis

Diagnosis is primarily clinical — a vet will assess gait, hoof temperature, digital pulses, and response to hoof testers. Radiographs (X-rays) of the hooves are essential in any moderate to severe case. They allow the vet to measure coffin bone rotation (in degrees) and sinking (in millimetres), which is critical for both treatment planning and prognosis. Repeat X-rays are used to track progression or improvement.

Blood tests for insulin, glucose, and ACTH (to screen for PPID) should be taken in any horse with unexplained or recurrent laminitis, as metabolic disease is the underlying cause in the majority of cases.

Treatment

Immediate Management

  • Box rest on deep bedding: Remove the horse from pasture immediately. Deep shavings, sand, or a supportive surface such as a memory foam mattress reduces sole pressure on the coffin bone. Avoid rubber mats, which provide no cushioning for a painful, potentially rotated sole.
  • Remove dietary triggers: Strip all sugary feeds, treats, and access to lush grass. Offer soaked hay and ask your vet how much to feed, but treat soaking as reducing sugar rather than removing it: when UK hays were soaked for up to 16 hours, they lost an average of 27% of their water-soluble carbohydrate (range 6% to 54%), and seven were still above the 100 g/kg dry matter ceiling suggested for laminitic animals afterwards (Longland and colleagues, Veterinary Record 2011). No fixed soak time makes hay safe, so have the forage analysed.
  • Frog support: Your vet or farrier may apply frog support pads (such as Styrofoam pads or commercial products like Soft-Ride boots) to transfer ground reaction force away from the toe and onto the frog and rear of the foot.

Pain Relief

  • NSAIDs: Phenylbutazone (“bute”) or flunixin meglumine are the most commonly used pain relief options. These must be used under veterinary guidance — long-term NSAID use carries its own risks, particularly for the gastrointestinal tract.
  • Acepromazine (ACP): Sometimes used in acute cases to promote peripheral vasodilation and improve blood flow to the hoof, though its use is now debated.

Farriery

Corrective shoeing is one of the most important treatment components. The goal is to provide mechanical support that reduces tension on the deep digital flexor tendon and redistributes load away from the toe. Common approaches include:

  • Heart bar shoes, egg bar shoes, or wide-webbed aluminium shoes with frog support
  • Breakover adjustment (rolled or squared toes) to reduce mechanical stress during the breakover phase of the stride
  • Deep-seated shoeing or impression material to support the entire solar surface
  • Regular farriery every 4–6 weeks in actively managed laminitic cases

Managing Underlying Conditions

Without addressing the root cause, laminitis will recur. Horses with EMS require strict dietary management and exercise programmes. Horses with PPID usually need daily medication (pergolide) to control ACTH levels. Work closely with your vet to test for these conditions and implement long-term management plans.

Prevention

  • Manage body condition: Aim for a body condition score of 4–5 (out of 9). Reduce weight gradually in obese horses with the guidance of a vet.
  • Limit grass intake: Use a grazing muzzle, strip-graze, or stable during high-risk periods (spring flushes, early autumn, sunny days following cold nights).
  • Test and monitor for metabolic disease: Annual ACTH and insulin testing is advisable for older horses and ponies, or any horse with a history of laminitis.
  • Soak hay: For high-risk horses, soaking hay reduces NSC content significantly.
  • Maintain regular farriery: Balanced hooves reduce uneven load on the laminae. Horses that go overdue for trimming are at greater risk.
  • Feed carefully after illness: Any horse recovering from severe systemic illness should be monitored closely for early signs of laminitis.

Prognosis and Recovery

Prognosis depends heavily on the severity of rotation or sinking and how quickly treatment began. Mild, acute laminitis with no radiographic changes and prompt treatment has a good prognosis — many horses return to full work. Horses with moderate rotation can often be managed back to comfortable pasture or light work, though it takes time and consistent farriery.

Severe rotation or sinking (particularly where the coffin bone penetrates the sole) carries a guarded to poor prognosis for return to ridden work, and humane euthanasia may ultimately be the kindest option. Horses with recurrent laminitis require permanent management adjustments — they are never “cured,” merely controlled.

When to Call the Vet

Call your vet immediately if your horse shows any of the following:

  • Sudden, unexplained bilateral front-leg lameness
  • The classic laminitic stance (weight shifted back, front legs pushed forward)
  • Hooves that feel abnormally hot
  • A bounding digital pulse at the fetlock
  • Any horse with known EMS or PPID that shows a sudden change in movement

Do not wait to see if it improves. Laminitis is a time-critical condition — the difference between calling the vet at first sign versus waiting 24–48 hours can be the difference between a horse that recovers and one that doesn’t.

Breeds Commonly Affected by Laminitis

While any horse can develop laminitis, certain breeds and types are significantly more susceptible due to their metabolic profiles:

  • Native and mountain breeds — particularly Welsh, Dartmoor, and Shetland ponies — evolved on sparse forage and are highly efficient metabolically
  • Warmbloods and heavy cobs
  • Arabians and Morgan horses can also be predisposed
  • Older horses (15+) are at elevated risk due to the higher prevalence of PPID in this age group

Frequently Asked Questions About Laminitis in Horses

Can a horse with laminitis ever go back to work?

Yes, many horses do return to ridden work after a laminitic episode, particularly if it was mild and treated promptly. Recovery depends on the degree of coffin bone displacement, the horse’s underlying health, and how well the condition is managed going forward. A vet and farrier working together — using radiographs to guide shoe fitting — gives the best chance of a positive outcome. Some horses with chronic or recurrent laminitis may only be suitable for light hacking or retirement from ridden work.

How long does laminitis last?

An acute episode typically peaks within the first 72 hours. Initial recovery (where the horse becomes more comfortable) can take 2–6 weeks with proper treatment and box rest. However, the structural changes to the hoof — and the management changes required to prevent recurrence — are permanent. Horses with a history of laminitis require ongoing dietary and hoof management for the rest of their lives.

Is laminitis the same as founder?

Laminitis and founder are related but not identical terms. Laminitis describes the acute inflammatory condition. Founder specifically refers to the mechanical displacement (rotation or sinking) of the coffin bone that can occur as a result of laminitis. Not all horses that develop laminitis will founder — it depends on the severity of lamellar damage and how quickly treatment is initiated.

What should I not feed a horse prone to laminitis?

Avoid all high-sugar and high-starch feeds: lush or fast-growing pasture grass (especially in spring and autumn), grain and concentrate feeds, apples, carrots, and other sugary treats, bread and cereal-based snacks, and haylage (which tends to be higher in sugars than dry hay). Stick to low-NSC forage, soak hay before feeding, and work with your vet to assess whether a balancer or mineral supplement is appropriate.