Imagine you have finger nails which grow all the way around the end of your finger rather than just on the upper surface. Then, imagine the finger nail being part torn from its bed and having to walk on it at the same time. This is the pain a horse feels with laminitis. Still drawing the comparison with finger nails, look at your own nails and see the fine striations growing towards their tips. These are the 'laminae'. Laminitis is inflammation of the laminae and can be caused by a range of different conditions.
Gluttony and excessive access to nutrients on the grass or with hard feed occurs widely. The nutrient value of grass varies enormously and is governed by sward quality, sunshine hours, warmth and land quality. The type of horse also influences risk assessment with small native breeds (Shetland) being top of the risk tree to athletic competition horses (thoroughbreds) being at the bottom. No horse is without risk. Knowledge and understanding of nutrition will limit your horses risk.
Isabelle Vets veterinary surgeons have been aware that we see an increased incidence of laminitis when the spring and early summer grass suddenly sprouts but we also see cases at other times of the year including at times, in the winter. The production of 'richer' grass was not in itself a sufficient answer. Initially it was believed that high protein content was the causative factor but in recent years it has become evident that it is the presence of a nutrient group called soluble complex carbohydrates (fructans) which pass to the hind gut of the horse and cause a massive change in the balance of the digestive bacteria of this area. Large amounts of lactate producing bacteria develop under these conditions and produce exotoxins which release enzymes from the basement membrane of the horses hoof laminae causing inflammation and separation of the hoof from the live dermal laminae. These complex carbohydrates are present in rich grass and particularly so in cereals (hence, laminitis after raiding the food bins) but also are present when pasture is 'stressed' such as after fertilizing, a hard frost or sudden change in climatic conditions. There is also vasoconstriction (closing down) of the capillaries in the hoof causing poor circulation and congestion. This explains why horses with laminitis have hot feet and a marked digital pulse. There is a medicine available that can limit the bacterial production of endotoxins. Please discuss this with your vet.
Insulin resistance and metabolic syndrome. Many owners are aware of ponies with great big crests and fatty flanks that just can’t shed the pounds. Another new concept in one of the many causes of laminitis is ‘metabolic syndrome’ where the horse’s ability to utilize insulin causes increasing blood glucose levels with fat deposition and increasing risk of laminitis. A simple blood test assesses a number of parameters which when taken as a whole can indicate whether your pony is suffering from this problem. Daily use of a human, insulin potentiating tablet can help reduce the risk.