Founder in Horses

By: Liz Schatz, DVM | Updated March 21, 2025

Defining Equine Founder

Founder is the rotation and/or sinking of the coffin bone that commonly happens in horses with chronic laminitis. The terms founder and laminitis are often used interchangeably, but for the purpose of this article, references to founder mean the rotation and/or sinking of a horse’s coffin bone.

How Laminitis May Lead to Founder in Horses

Laminitis refers to inflammation of the laminae, which are the somewhat delicate tissues that connect the coffin bone (located inside the hoof) to the hoof capsule. When this condition is severe or lasts for a prolonged amount of time, the laminae can begin to release their hold on the coffin bone. The deep digital flexor tendon (DDFT) can then pull the coffin bone in such a way that the tip of the coffin bone turns toward the ground. This is called rotation.

Sinking occurs when the entire coffin bone moves toward the ground without rotating. However, rotation and sinking may happen at the same time. Additionally, inflammation often leads to restricted blood flow to the foot. These changes cause many issues within the hoof and can be extremely painful.

Video on founder vs laminitis

Watch this Ask the Vet video where Dr. Lydia Gray explains the differences between founder and laminitis.

Stages of Developmental Laminitis to Chronic Founder

Episodes of laminitis and founder can be better understood by knowing which phase of the disorder a horse is experiencing. In turn, this helps your veterinarian make the most appropriate recommendations for treatment and management.

• Developmental: The period from the initial onset of inflammation to the first sign of foot pain.
• Subacute and Acute: Subacute refers to less than 72 hours after the onset of clinical signs, while acute refers to more than 72 hours after the onset of clinical signs. No rotation or sinking has occurred yet.
• Chronic: A variable period when a horse could founder.
  • Acute-on-Chronic: Refers to an acute episode in a horse that has previously been diagnosed with chronic laminitis.

Signs and Symptoms of a Laminitic or Foundering Horse

If you notice any signs that your horse may be in pain, reach out to your veterinarian as soon as possible. Here are some common signs of laminitis and founder in horses:

• Lameness, often very severe.
• Reluctance to bear weight on one or more limbs.
• Rocking back on the hind limbs to minimize weight on the front feet (known as “sawhorse stance” or “founder stance”).
• Lying down more than usual or a reluctance to stand up.
• Increased digital pulses in the affected limb.
• Changes in the appearance of the sole or frog of the foot.
• Increased heat in the foot.
• Protrusion of the tip of the coffin bone through the sole of the foot.
• The appearance of dishing (flare or concave slope of the hoof) or growth rings (ridges) in the hoof capsule with chronicity.

What Causes a Horse to Founder?

A horse may become laminitic or founder due to certain circumstances related to:

• Diet: Due to an overload of grain (non-structural carbohydrates).
• Pasture / Grass: Eating too much lush grass, often during the spring, is referred to as grass founder in horses.
• Inflammatory, infectious, or toxic conditions.
• Endocrine Conditions: Insulin dysregulation due to Equine Metabolic Syndrome (EMS) or Pituitary Pars Intermedia Dysfunction (PPID) may lead to founder.
• Mechanical Issues: Overloading of the limb opposite a painful or injured limb.
• Corticosteroids: Following administration of a corticosteroid (such as prednisone or dexamethasone) to a horse predisposed to laminitis. However, this cause is only supported by anecdotal evidence and not by clinical research.
• Genetic predisposition: Ponies, miniature horses, and other breeds may be susceptible to developing founder due to a number of factors, such as metabolic issues and body condition.

Veterinary Diagnostics

If you think that your horse may be foundering, reach out to your veterinarian right away. In many cases, early diagnosis and treatment can greatly improve your horse’s prognosis.

Each veterinarian will examine a potentially laminitic or foundering horse differently. This workup will likely include a full physical exam, lameness exam (if appropriate), and radiographs (x-rays) of the feet. Your veterinarian may recommend bloodwork to determine whether there is an underlying infection or disorder, such as EMS or PPID.

Treatment of Founder or Laminitis

Treatment recommendations will depend on the duration and severity of the signs and symptoms involved in each horse’s case. Care should focus on relieving your horse’s pain and shortening the episode of laminitis or founder, if possible.

Subacute and acute phase treatments:

• Limiting your horse to strict stall rest with deep bedding.
• Administering NSAIDS, such as phenylbutazone (bute), flunixin meglumine (Banamine®), or firocoxib (Equioxx®) to reduce pain and inflammation.
• Cryotherapy (ice therapy) applied to the feet to minimize damage to the laminae.
• In some cases, medications like aspirin, heparin, acepromazine, pentoxifylline, or isoxsuprine may be used to improve blood supply to the foot. These medications should only be used under the close supervision of a veterinarian.
• Having your horse wear specialized hoof boots or therapeutic shoes to improve their level of comfort.

Chronic founder treatments:

• Any of the above treatments during the subacute and acute phases, as needed.
• Providing therapeutic trimming and shoeing.
• Applying a foot cast to stabilize the entire hoof.
• Deep digital flexor tenotomy (surgical bisection of the deep digital flexor tendon) to release the pull of the DDFT, if necessary.

Supplements That May Lend Support

In addition to management changes, hoof care, and medications, there are specific ingredients and supplement formulas that may support horses with hoof issues. Since founder is a complicated medical condition, it is always recommended to check with your veterinarian prior to making any changes to your horse’s regimen. Some ingredients to discuss with your veterinarian include:

• Antioxidants: N-acetylcysteine, vitamin C, vitamin E, grape seed extract, and spirulina.
• Support for a normal inflammatory response: MSM, devil’s claw, boswellia, goldenrod, oat beta glucan, turmeric, yucca, and bromelain.
• Laminae support: Omega fatty acids and hops.
• Healthy hoof circulation: Citrus bioflavonoids, arginine, and jiaogulan.

Recovery

The prognosis for horses with laminitis or founder is extremely variable. Horses with mild, single episodes of laminitis tend to have a good prognosis. Horses that have more severe episodes or develop chronic founder tend to have a guarded prognosis. In severe cases, humane euthanasia may be recommended, particularly if there is pain that cannot be controlled.

Prevention of Founder in Horses

There are strategies horse owners can take to minimize the possibility of laminitis and/or founder, including:

• Grain should be kept in secure containers (preferably behind a shut door, too) so your horse cannot get to the feed.
• Horses that have EMS or PPID should have limited or no access to lush pasture. Many of these horses are kept on dry lots or turned out wearing a grazing muzzle. This is particularly important in the spring and late in the day when sugar levels in grasses are high.
• Horses with insulin dysregulation should receive limited amounts of non-structural carbohydrates (NSC) in their diet. There are many fortified grain options available that are manufactured with very little NSC content.
• Horses should be kept at a healthy weight and receive regular, professional hoof care.
• Those with an injured limb should have the opposite limb supported as much as possible, for example, applying standing wraps to both front or hind legs.

Unfortunately, it is impossible to guarantee that a horse will not develop laminitis or founder. As always, your veterinarian is the best resource for keeping your horse healthy and happy.

Evidence-Based Resources

1. Belknap, James K. “Treatment of Complications of Laminitis.” American Association of Equine Practitioners Proceedings, vol. 63, 2017, pp. 23–26.
2. Hunt, Robert J, and Robin E Wharton. “Clinical presentation, diagnosis, and prognosis of chronic laminitis in North America.” The Veterinary clinics of North America. Equine practice vol. 26,1 (2010): 141-53. doi:10.1016/j.cveq.2009.12.006