Laminitis is the inflammation of the Laminae.
There are two layers of interlocking Laminae, one is attached to the wall of the hoof, the other is attached to the pedal bone. As the laminae become inflamed the two layers begin to separate. This can be likened to the two sides velcro being pulled apart. Eventually the pedal bone will start to rotate and move downwards, this is excruciatingly painful for the horse. In the most serious cases the pedal bone may eventually perforate the sole of the hoof, unfortunately often results in euthanasia.
What causes laminitis?
There are 3 causes of laminitis.
Overload: When one leg is injured the horse will bear all it's weight on the opposite leg. This can cause that leg to become laminitic.
Inflammatory: This is caused by toxins being absorbed into the blood stream. Consuming a large amount of starch rich grain all in one go, the grain is not fully digested and builds up in the hind gut where it starts to ferment and release toxins.
Septic conditions, for example where the placenta is retained after giving birth.
A serious bout of colic where the gut is damaged.
All of these can cause severe illness that will affect the laminae.
Metabolic: This is by far the most common cause of laminitis. There are 2 types, both are the result of an abnormal control over carbohydrate metabolism. Because of this they have an excessive response to insulin; starch in grain and sugars in grass.
PPID. Pituitary Pars Intermedia. (Cushings Disease) This is a disease of ageing. Part of the pituitary gland starts to secrete an excessive amount of hormones. Some of these hormones affect the carbohydrate metabolism which results in high insulin levels which in turn can cause laminitis
EMS. Equine Metabolic Syndrome. Many of our native breeds are genetically predisposed to EMS. The three factors that charaterise EMS are obesity, insulin resistance and laminitis. Horses susceptable to EMS that consume large amounts of sugars will have high levels of insulin which in turn will result in laminitis.