Laminitis Consultations

What is Laminitis?

It is important to understand the basic anatomy of hoof to better understand what laminitis is. 

• Put simply, the hoof is comprised of two main parts.

  • The outer hoof “capsule” which comprises of the hoof wall and the sole of the foot. This is made of a keratin-based material which encapsulates the whole foot.

  • The inner bone which is called the pedal bone, often referred to as the “coffin bone, third phalanx, or P3”, which is part of the distal limb skeletal structure.

• The hoof capsule is attached to the pedal bone by soft tissue structures called “lamellae” which hold the pedal bone in the correct position.

• Laminitis occurs when these lamellae become inflamed, which weakens the laminae structures, causing the attachments to weaken, resulting in changes in the position of the pedal bone. With the weakened attachments, the pedal bone may rotate away from the hoof capsule and/or the pedal bone may sink towards the sole of the foot. These changes can be seen on x-rays (as above).

What are the causes of Laminitis?

Laminitis can develop for several reasons, and often there is not a single cause but multiple contributing factors. These can be summarised by the categories below:

• Endocrine: 

  • Did you know 90% of laminitis cases have an underlying hormonal cause? 

  • The two main endocrine diseases involved are:

    •  Equine Metabolic Syndrome (EMS) which is characterised by obesity and insulin resistance which can occur in any aged horse

    • Cushing’s disease aka Pituitary Pars Intermedia Dysfunction (PPID) which is characterised by high levels of adrenocorticotrophic hormone (ACTH) and high cortisol levels, typically seen in older horses over 12 years old. 

  • Horses can have EMS or PPID, but they can also suffer from both diseases at once (see diagram below).

• Nutritional: 

  • Carbohydrate overload has been shown to cause laminitis, either through grasses high in non-structural carbohydrates (NSC) aka sugars/starches, or through grain overload in hard feeds high in oats/corn/barley etc.

  • Horses that are “easy-keepers”, obese, cresty necked, or insulin resistant (EMS) are more sensitive to episodes of laminitis caused by carbohydrate overload. 

• Inflammatory diseases:

  • Laminitis can occur secondary to severe disease processes happening elsewhere in the body such as colic, diarrhoea, pneumonia, retained foetal membranes.

• Mechanical overload:

  • Excessive weight bearing on one foot can cause laminitis, which is typically seen when there is severe injury to opposite foot that cannot weight bear.

• Iatrogenic:

  • Unfortunately, there is a risk of laminitis when using corticosteroid drugs to treat another issue in the horse, so care needs to be taken with the use of steroids, particularly if the horse is suffering from EMS.