What is laminitis?

Laminitis is one of the most serious, crippling disease of horses, ponies and donkeys. Severe, recurring cases of laminitis can reduce a horse’s active life or result in him being put to sleep to prevent further suffering.

Treatment, whether successful or not, can require a lot of time and money, and requires a good deal of energy from the owner for an extended period of time. It’s no surprise, then, that there is plenty of research going into treating this.

What happens when a horse gets laminitis?

Laminitis is a painful inflammatory condition of the laminae, which are supporting, leaf-like tissues that bond the hoof wall to the pedal bone in the horse’s hoof. It can affect any horse, of any age or sex, at any time of the year. And although it’s traditionally considered a disease of fat ponies, laminitis can be triggered by a variety of metabolic or physical causes in any horse.

It’s caused by weakening of the laminae within the hoof, leading to painful tearing of the support structure suspending the pedal bone within the hoof capsule. If laminitis is not treated promptly, the pedal bone can drop (these cases are described as ‘sinkers’) or rotate downwards. Laminitis and founder are not the same. The term founder describes the sinking of the horse’s pedal bone. Laminitis can, but does not always, result in founder.

What are the causes of laminitis?

Despite much research and study, our understanding of laminitis is far from clear. However, it is universally agreed that it stems from a diverse set of processes (including sepsis, endocrine disorders and excessive weight) that results in inflammation of the laminae, which damages the pedal bone’s support structure.

Common causes of laminitis include:

  • Excessive intake of grass or grain engorgement – for example, if a horse or pony gets into the feed room.
  • After-infection – for example, a mare who has recently foaled and has retained the afterbirth.
  • After administration of excessive doses of certain drugs, such as corticosteroids (eg, prednisolone).
  • Enlargement of the pars intermedia of the pituitary gland (PPID) or Cushing’s disease.
  • High insulin levels such as seen in equine metabolic syndrome.
  • Concussion from riding on hard surfaces.
  • Excessive weight-bearing on one leg due to severe injury or lameness in the opposite leg.
  • Stress from long-distance transport.