Laminitis is a crippling and painful condition affecting horses’ feet. The tissue (lamellar tissue or laminæ) which connects the hoof to the bone (coffin bone, pedal bone, third phalanx or P3) inside becomes inflamed and the hoof can start to tear off with catastrophic results. In the worst cases, without prompt and proper treatment whole hoof can become detached or permanently deformed.
Once started, it is difficult and time consuming to heal and often leads to euthanasia.
Pain management is a big issue. The hoof is equivalent to a human’s finger or toe nail, so imagine what it would be like to have that tearing off and having to walk on it.
The treatment of laminitis often involves a Vet, Farrier and a great deal of time and effort from the horse’s owner. Sometimes a specialist (or remedial) Farrier and additional care professionals are needed as well.
A surprising number of horses are afflicted by laminitis each year despite better knowledge of the condition. It can strike any size or breed of horse, well cared for or otherwise and is not, as commonly thought, just a problem with fat hairy ponies.
The causes of laminitis are complex, varied and not fully understood. They fall into two main groups - systemic whereby the inflammation starts as a result of a reaction within the body, and mechanical which included external causes such as concussion from hard ground or from external injury.
Symptoms vary from the very obvious acute ones to the extremely subtle and chronic. The latter are often missed completely or thought to be other problems.
Laminitis results when the sensitive tissue (lamellar tissue or laminæ) which connects the hoof to the wedge- shaped bone (coffin bone, pedal bone, third phalanx or P3) inside becomes inflamed. If the inflammation is prolonged or severe then the pedal bone can start to tear away from the hoof wall. It will then rotate downwards until it puts pressure onto the inside of the sole. In extreme cases the bone can penetrate the sole or become detached completely.
A laminitic hoof will usually be very sensitive around the underside of the toe area and the horse will react when a Farrier applies hoof testers to that area.
Laminitis can affect any or all of a horses feet, but is generally more prevalent in front feet because of the extra weight carried. A horse typically supports 60% of its body weight on its front feet.
Laminitis is often referred to as either Acute or Chronic.
Acute cases are those where there is a sudden onset of the condition including pain and inflammation of the laminae whereas chronic is used to describe ongoing or recurring cases with established rotation of the pedal bone.
A horse with pedal bone rotation is said to have foundered and the condition is sometimes referred to as Founder, often interchangeably with Laminitis.
When separation of the pedal bone and its subsequent rotation has started, the bond to the hoof wall becomes progressively weaker. There is a large tendon (deep digital flexor tendon) attached to the pedal bone which exerts a very large rotational force on it, and that, combined with the horse's weight acting downwards through the bone can rapidly produce an avalanche effect.
If the pedal bone breaks through the sole it becomes a very serious case and the prognosis will not be good. It is not, however, always fatal and aggressive and prompt treatment by Vet and Farrier can sometimes rescue the horse back to pasture fitness or even full work. The treatment will be difficult, lengthy and expensive.
Once the initial problem has been brought under control there are often further complications. Parts of the laminae will almost certainly have died leaving spaces inside the hoof. There will probably be an accumulation of pus etc within these spaces which will eventually make its way out as a series of abscesses erupting through the sole or coronary band.
Furthermore, the rotated pedal bone will distort the hoof growing bed at the top front of the hoof so new hoof will grow far more slowly at the front than the back leading to characteristic wedge shaped growth rings on the hoof instead of the normal parallel ones. The Farrier will be able to trim the hoof accordingly and eventually hope to get new growth running parallel to the pedal bone again. It can take several years to achieve a relatively normal hoof again.