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.

 
Healthy vs Laminitic Horse Hoof
 

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 turnou