Top 17 Risk Factors for Laminitis in Horses [+ How to Prevent]

One in ten horses is affected by laminitis each year. This painful condition involves damage to the hoof laminae, leading to varying degrees of lameness. ^[1]

Although laminitis affects the hooves, the condition is often initiated by dietary and metabolic factors. Laminitis can also result from infection with a systemic inflammatory response or excessive mechanical stresses on the hooves.

Many horses recover completely, but others have lasting damage and are not able to resume their previous level of work.

Once a horse experiences laminitis the risk of reoccurrence increases, and proper management is critical to support recovery and maintain a sound horse.

All breeds and ages of horses are susceptible to laminitis, but some horses have a higher risk due to genetic factors. There are also common lifestyle factors that contribute to the development of this condition. ^[1]

This article will review the top 17 risk factors for laminitis in horses and discuss how to address these risk factors and prevent laminitis in your horse.

Laminitis Overview

Approximately 600 interlocking primary laminae in the horse’s foot provide structural support and connect the coffin bone to the hoof wall. Each of the primary laminae has approximately 100 secondary laminae which are branches off the primary.

Laminae are both sensitive – originating from the deeper tissues and live tissue – and insensitive – inner branches of the hoof wall which do not have nerves or blood supply.

When laminitis occurs, the sensitive soft tissue structures become damaged and stretch, resulting in debilitating pain for the horse.

If the condition progresses to founder, the laminae eventually separate and the coffin bone loses support. The coffin bone may sink or rotate downwards and create pressure on the sole.

Some horses fail to regain soundness after laminitis and struggle with the condition as a chronic issue. In severe cases, laminitis can lead to euthanasia – approximately, 7% of equine deaths are associated with laminitis. ^[2]

There are four main types of laminitis that can occur:

• Endocrinopathic laminitis – relating to metabolic causes, such as grain overload or pasture-associated laminitis
• Sepsis-associated laminitis – occurring as a secondary effect of illness/infection and associated with a systemic inflammatory response
• Mechanical laminitis – caused by excessive weight bearing or support limb laminitis
• Toxicity-related laminitis – caused by exposure to toxic metals or plants

Regardless of whether laminitis is caused by mechanical, metabolic or other factors, the condition can worsen quickly. If laminitis progresses to founder, the hooves and inner structures of the lower leg may sustain irreversible changes and result in permanent lameness.

Typical Signs of Laminitis

Horses affected by laminitis commonly display physical and behavioural signs of the condition. There can also be changes in hoof quality and signs of metabolic dysfunction that indicate your horse is at risk of laminitis.

Physical and Behavioural Signs

Abnormal Stance: Affected horses avoid bearing weight on their front legs by positioning them in front of the body, stiffening (bracing) muscles of the legs and shoulders, shifting weight to the hind legs.

Objection to movement: The intense pain caused by laminitis can make horses reluctant to move or make sharp turns.

Altered gaits: Horses with laminitis may be lame in some or all legs and exhibit a shortened stride.

Shifting weight: Horses with foot pain may alternate bearing weight on their legs by lifting them up and placing them down again.

Increased digital pulse: Horses with laminitis may have a stronger digital pulse caused by restricted blood flow in the extremities.

Changes in Hoof Quality

Flaring of the hoof wall: A damaged laminar attachment between the coffin bone and the hoof wall can cause the hoof to flare or have a dished appearance.

Rings on the hooves: Inflamed laminae and restricted blood supply to the hoof can initiate the development of hoof rings.

Stretched white line: Located around the inner edge of the hoof, the white line can become widened when the laminar connection is unhealthy.

Metabolic Disturbances

1. High insulin levels: Increased insulin levels are a known precursor for laminitis. ^[3][4]
2. Obesity: Obesity is present in approximately 50% if horses with equine metabolic syndrome and has been associated with laminitis ^[5]
3. Regional fat deposits: Horses with endocrinopathic laminitis may exhibit accumulations of fat deposits in areas including the neck, withers, rump, and genitalia.

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Top 17 Risk Factors for Laminitis

Research on equine laminitis has identified several risk factors for the condition. ^[6] Understanding these factors is critical to reducing your horse’s risk profile and preventing adverse outcomes.

Although laminitis may not always be preventable in every case, good management practices can help you improve your horse’s prognosis. Below are 17 of the most common risk factors for laminitis.

1) A Previous Attack of Laminitis

Horses that have had acute laminitis in the past may have sustained damage to the internal structures of their hooves, making them more vulnerable to the condition in the future.

Laminitic horses can experience recurrence of the condition if the original risk factors that caused the first episode of laminitis were not fully addressed.

Preventive strategy:

A veterinarian should assess your horse to determine if a case of laminitis has completely resolved. This assessment will typically involve blood testing and reviewing the horse’s full medical history and current work regimen.

Work with a nutritionist to design a feeding plan that supports your horse’s recovery and reduces the likelihood of recurrence.

2) Genetics

Certain breeds of horses are genetically predisposed to metabolic syndrome and high insulin (hyperinsulinemia). This occurs more frequently in easy keeper breeds, which are theorized to have one or more genes that promote survival during times of drought and feed scarcity.

Certain genes may predispose horses to metabolic dysfunction and laminitis. Breeds such as Saddlebreds, Morgans, Paso Finos, Arabians, Andalusians, and Welsh, Shetland and Dartmoor ponies are considered more vulnerable to equine metabolic syndrome and laminitis. ^[20]

Preventive strategy:

Determine if your horse is a high-risk breed or has a high prevalence of laminitis among relatives. Easy keepers need to have their diets closely managed to avoid this condition.

Know the warning signs of laminitis so it can be treated promptly if your horse develops the condition.

3) Diets High in Sugar and Starch

Feeding a diet high in non-structural carbohydrate (NSC) components including starch and sugars from grain or lush pasture can aggravate hyperinsulinemia and increase the risk of laminitis in horses.

A 3-year prospective study involving 448 ponies in the UK identified low adiponectin and elevated basal or stimulated insulin as the only predictors of pasture laminitis. These are both hallmarks of metabolic syndrome. ^[23]

Preventive strategy:

Feed a diet predominantly comprised of hay that is low in ESC (simple sugars) and starch.

Eliminate concentrates such as grain and sweet feeds in the diet.

Replace balancers that contain potentially harmful fillers with a pure vitamin and mineral supplement such as AminoTrace+.

4) Access to Lush Pasture

Quality pasture can be a valuable component of a healthy diet for your horse. However, certain types of pasture plants can contain high amounts of sugar and starch, which increase the risk of laminitis.

Several factors including weather, maturity, time of year, and the time of day influence the amount of sugar and starch in pasture grass.

Lush grasses may provide more nutrients than horses need, particularly in the springtime when the grass is growing quickly and is rich in calories. However, grass can be a hazard to laminitis-prone horses at any time of year.

Preventive strategy:

Avoid turnout in lush pasture and feed your horse hay that has been appropriately selected to match their energy needs.

Horses vulnerable to laminitis should be fed forages that contain less than 10% combined sugar and starch. Get a hay analysis to ensure you are choosing the right forage for your horse.

Horses at risk of laminitis may require turnout with a grazing muzzle or appropriate pasture management strategies, such as strip grazing. Grazing horses in the early morning before the sun rises is recommended because the sugar content of grass is lowest at this time of day.

Do not turn your laminitic horse out in the morning if the overnight temperatures have dropped below 5°C or 40°F. At these low temperatures, plants will stop growing and retain sugar, resulting in higher levels for horses grazing in the morning.

5) New Access to Grass

Horses that are newly turned out onto grass after having no access to grass for four weeks or more have a much higher risk of developing laminitis.

These horses were seven times more likely to become laminitic compared to horses that had continuous access to grass or no access to grass. ^[6]

Preventive strategy:

Gradually transition your horse to turnout on pasture after a long period of time with no pasture access, such as in the springtime. Consider pasture management strategies such as wearing a grazing muzzle, strip grazing or turning out for limited periods of time when sugar and starch levels are lowest in grass.

Some horses with metabolic syndrome may not tolerate any pasture.

6) Pituitary Pars Intermedia Dysfunction (PPID)

Horses with PPID (sometimes referred to as Equine Cushing’s Disease) have a higher risk of developing laminitis. ^[7] A research study in Finland involving 36 horses with laminitis determined that 89% had endocrine disease, 1/3 of which was PPID. ^[8]

PPID is a metabolic condition that causes excessive production of the hormone adrenocorticotropin (ACTH) and a resulting increase in cortisol levels. High blood cortisol levels promote elevated insulin, which is directly associated with an increased laminitis risk.

Signs of PPID include an excessively long hair coat, reduced muscle mass, lethargy, and increased susceptibility to infections. Laminitis is a key indicator of PPID and often develops before the other signs. Fall is the most dangerous time of the year for undiagnosed PPID horses because the seasonal ACTH rise is exaggerated.

Preventive strategy:

If your horse is showing signs of PPID, consult with a veterinarian to have your horse’s blood tested. The standard treatment for PPID is the oral administration of the drug pergolide.

Pergolide may help to improve hormonal imbalances in horses with PPID, but dietary management is still critical to restrict the intake of sugar and starch. Horses with PPID should be tested annually to determine if their medication dosage requires adjustment.

7) Metabolic Syndrome

Horses with Equine Metabolic Syndrome (EMS) have elevated levels of insulin, a hormone that allows cells to metabolize sugar for energy production. As insulin sensitivity decreases, the pancreas responds by secreting more of this hormone. ^[9][10]

In IR horses, insulin remains at a high level for a prolonged period. Research suggests a direct link between elevated insulin levels and the development of laminitis. ^[27][28]

Preventive strategy:

Horses suspected of having EMS should undergo diagnostic blood testing to detect the condition. Horses with hyperinsulinemia typically require diets low in sugar and starch and an appropriate exercise regimen to manage their condition.

8) Excess Fat Deposits

Abnormal fat deposits on the neck crest, tailhead, chest, withers are characteristic of horses with metabolic syndrome. Even metabolic horses of normal or low body weight will typically have a cresty neck.

A research study involving 26 ponies compared the relative metabolic risk for overall body condition scores to scores of fat deposits on the neck. The study found that the neck score was more predictive of insulin dysregulation than an overall body condition score. ^[12]

Preventive strategy:

Horses that are prone to storing excess fat require careful management. These horses typically benefit from a calorie-restricted diet that is low in sugar and starch and an appropriate exercise program.

If your horse develops fat deposits on the neck – known as a cresty neck – consult with a nutritionist for strategies to reverse this condition. The horse should also be tested for metabolic syndrome.

9) Recent Weight Gain

Horses that have gained weight in the last 3 months have a nearly four-fold increase in their risk of laminitis. Recent weight gain indicates a diet that is over-supplying energy or could mean that your horse’s activity level has decreased. ^[6]

Preventive strategy:

Regularly body condition score your horse and make adjustments to their diet and exercise program if you notice that your horse is gaining weight.

10) Exposure to Black Walnut Shavings

Contact with or ingestion of black walnut shavings is a known cause of laminitis in horses. Exposure to black walnut shavings can lead to acute laminitis within one to two days by altering blood flow to the hoof and exerting other systemic effects. ^[29]

Preventive strategy:

Avoid using black walnut shavings for bedding stalls or in other areas where horses are kept.

11) Acute Illness

Illnesses such as colic or diarrhea, and inflammation in the small intestine can promote the development of laminitis by making it easier for toxins to penetrate the intestinal barrier and circulate into the bloodstream, resulting in a systemic inflammatory response syndrome (SIRS).

Retained placenta, severe burns and any severe systemic illness such as metastatic “bastard” Strangles can also result in SIRS. ^[22]

Upon entry into the peripheral blood supply, Streptococcal toxins can impede circulation through the lamellar tissues and activate enzymes that weaken the laminae. ^[21]

Preventive strategy:

Ensure your horse is regularly examined by a veterinarian and promptly treat any illness to reduce the risk of laminitis.

Mares that have recently given birth should be assessed to ensure the placenta is not retained.

12) Trauma to the Hoof

Mechanical laminitis can occur if the wall of the hoof becomes separated from the bone or is severely compromised causing damage to the underlying laminae.

An overly long toe, severe foot clubbing, or excessive concussion, can cause damage to the laminae and result in laminitis.

Preventive strategy:

Provide regular hoof care for your horse from a qualified farrier using proper trimming and/or shoeing practices. Treat any hoof injuries promptly to avoid complications that could lead to laminitis.

13) Soft Tissue Injury

Horses with soft tissue injuries, including ligament and tendon injuries, are more likely to develop laminitis after their injury. ^[11]

These injuries occur most frequently in active sport horses between the ages of 11 to 15 years. Injured horses are typically given limited turnout and have long periods of inactivity or field rest. ^[31]

Tendon and ligament injuries also often cause overloading of the opposite leg to avoid or reduce the pain. Shifting weight off the injured leg overloads the opposite foot and may cause supporting limb laminitis (SLL).

Laminitis may also develop in response to prolonged periods without exercise and inadequate adjustment of the diet, resulting in metabolic or circulatory issues.

Preventive strategy:

Speak with a veterinarian to develop a training and rehabilitation program that supports your horse’s recovery. Avoid restricting movement for longer than necessary and adjust your horse’s diet to match their energy demands while recovering from an injury.

Use a support wrap on the opposite leg and monitor carefully for pulses or heat.

14) Stall Rest

Horses that need to be put on stall or box rest should be managed carefully to avoid laminitis. Stall rest is defined as being confined to a stable or shelter for 24 hours per day with no exercise.

One study found that horses on stall rest during the previous week had a three-fold increase in their risk of acute laminitis. This may be linked to changes in feeding and exercise patterns. ^[6]

Horses on stall rest are also often suffering from injuries and may be more likely to develop supporting limb laminitis (SLL). This mechanical form of laminitis occurs when the horse shifts weight from an injured limb to the opposite limb, resulting in excessive weight-bearing and compromised blood supply. ^[6][18]

Preventive strategy:

If your horse is on stall rest for an injury, monitor them closely and speak to your veterinarian about strategies to prevent SLL. One study found that raising the heel on the supporting foot can improve blood flow and reduce the risk of supporting limb laminitis. ^[30]

15) Sudden Temperature Drops

Laminitis is most commonly associated with springtime in the minds of horse owners, but cold winter conditions can also predispose a horse to laminitis, so-called winter laminitis. ^[6]

One study found that horses were four times more likely to develop laminitis between the months of December to February compared to March to May. ^[6]

This increase in risk is not fully understood. However, a sudden decrease in temperature can impair circulation to the hooves, leading to pain and inflammation. This type of hoof pain is most likely to occur in horses with metabolic syndrome who already have elevated levels of endothelin-1 and vasoconstriction. ^[24]

Preventive strategy:

Horses that are already at an elevated risk for laminitis should be carefully monitored in the winter for signs of foot soreness. Follow this guide on caring for your horse in the winter.

Blankets, leg wraps and lined hoof boots help protect from cold stress and direct cold effects. Jiaogulan may be used to support nitric oxide levels within the blood vessels (endogenous nitric oxide) and counteract vasoconstriction. ^[25]

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16) Signs of Foot Soreness

Horses that appear to be lame or foot-sore after receiving farrier care have a higher risk of laminitis.

It is theorized that these horses may develop laminitis as a result of poor shoeing or trimming practices. ^[6] However, it’s also possible that the farrier care draws attention to previously unnoticed signs of laminitis.

Preventive strategy:

Seek veterinary attention for horses that show signs of foot soreness after shoeing or trimming. Prompt care may help to prevent a serious adverse outcome.

17) Use of NSAID Medications

Horses given non-steroidal anti-inflammatories (NSAIDs) for pain had a higher risk of developing laminitis. These drugs – such as phenylbutazone – are commonly used in older horses to address arthritic joint pain.

NSAIDs can worsen vasoconstriction in animals with metabolic syndrome by interfering with vascular nitric oxide production. ^[26]

The use of NSAIDs could also be linked to conditions leading to abnormal weightbearing or even to early laminitis that was not recognized as such.

Preventive strategy:

Avoid long-term use of NSAID medications and always follow dosage guidelines closely.

If your horse uses NSAIDs to address joint pain, consider safe supplement options that help to promote joint health and have a lower risk of side effects.

Summary

There are many steps you can take to help lower your horse’s risk of laminits. Some of the most important feeding and management practices to adhere to include:

• Feed a diet low in hydrolyzable carbohydrates – Feed a low sugar, low starch, forage-based diet and avoid grains and commercial feeds that raise insulin levels and increase inflammation.
• Regularly Monitor Weight – Check your horse’s weight and body condition regularly. Adjust your horse’s diet, exercise, and other management factors as needed.
• Provide Regular Farrier Care – Ensure your horse receives regular trimming/shoeing from a qualified farrier to maintain healthy hooves.
• Treat Metabolic Disease – Horses with insulin resistance and PPID should be treated to reduce the risk of laminitis.
• Supplement with jiaogulan – Metabolic horses can benefit from jiaogulan (Gynostemma pentaphyllum) to support circulation in the hoof.

Make sure that your horse’s diet provides all of the essential nutrients required for healthy hoof growth. Key nutrients include amino acids, biotin, and microminerals including copper and zinc. ^{[13][14][15][16][17]}

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Speak to a nutritionist to design a balanced feeding plan to reduce your horse’s risk of laminitis. Submit your horse’s information online for a free consultation.