Laminitis
Laminitis is an increasingly common disease that we see in horses and ponies. Traditionally laminitis is reported in the early grazing season when horses have been turned out to fresh spring grass and show signs of moderate to severe lameness, usually of the front feet. However we are now seeing severe cases of laminitis throughout the year. Owners often underestimate its potential to cause longterm unsoundness. It is not uncommon for severe and uncontrolled cases to require euthanasia on the humane grounds of incurable suffering.
What is laminitis?
Laminitis, in its simplest form, is inflammation of the sensitive layers (laminae) of the hoof. The pedal bone is suspended within the hoof by laminae. In laminitis these soft tissues become damaged resulting in pain, inflammation and, in some cases, the formation of gaps between the laminae. In very mild cases, appropriate treatment will resolve the problem quite quickly with no lasting effect. If the inflammation is more severe and progressive, the sensitive laminae may die with consequent loss of support between the pedal bone and horny hoof wall. This can result in separation of the pedal bone from the hoof with rotation and/or sinking of the bone within the hoof. As the horse stands and moves on its feet, penetration of the sole by the tip of the pedal bone can follow, with fatal consequences.
What Causes Laminitis?
Laminitis is caused by interference of the blood supply to the sensitive laminae of the foot. There are many conditions that can lead directly or indirectly to this including
- Overfeeding, which is by far the most common cause
- Excessive concussion due to fast exercise on hard ground or turn out on hard, dry paddocks
- Neglected feet or poor trimming and shoeing resulting in long toe/low heel conformation
- Toxaemia associated with severe infections
- Excessive weight bearing on one leg due to an injury or pain in the opposite leg
- Drinking a large quantity of cold water when overheated
- Horses or ponies with a history of laminitis are susceptible to recurrence.
- Some old horses which have chronic or recurrent laminitis have tumours of their pituitary glands; also known as Cushing’s disease.
How can I recognise the early signs of laminitis?
In mild cases of laminitis, the horse or pony may appear slightly ‘pottery’. The forelimbs are most commonly affected although it is possible for the hindlimbs only or all four feet to be affected. Often one foot is worse than the others. The affected foot or feet may appear abnormally warm to the touch and the pulse taken at the heel’s arteries may appear particularly strong. Laminitic horses will often stand with their hindlimbs well under the body and forelimbs stretched out in front, in an effort to keep weight off the painful front feet. This characteristic stance is almost diagnostic of laminitis. Affected horses will move with their heels landing first to try to avoid concussion to the painful toe region. If all four feet are affected, they may lie down for long periods or may constantly lift their feet alternately from the ground. More severe cases result in inability or reluctance to move at all and horses with severe rotation and sinking will often be unable to bear any weight on the affected limb or limbs. It is important to realise that laminitis can progress from mild to severe even if early treatment is instigated. Early warning signs must be heeded and action taken immediately.
What can be done?
Mild cases respond to stable rest, a restricted diet, and anti-inflammatory medication. More severe cases may also need remedial hoof trimming and shoeing and anti-inflammatory medication for a prolonged period (often many months). In cases of chronic pedal bone rotation, progressive remedial trimming to shorten the toe and lower the heel will gradually return the hoof to a more comfortable conformation in relation to the pedal bone. In horses where there is rotation or sinking of the pedal bone, radical trimming and shoeing may be required. Some cases progress despite all efforts of treatment and euthanasia is the only option. We often have to Xray horses feet to assess fully the degree of laminitic change within the feet.
Can it be prevented?
Horses and ponies have evolved in the wild to work hard for poor quality food and any individuals with access to good grazing should be watched carefully for signs of becoming overweight or pottery. When grass growth is lush, grazing should be restricted and exercise should be increased to regulate body weight. Sudden increases in concentrate food intake should be avoided and fast work on hard surfaces should be avoided.