THERE ARE SEVERAL MAIN TYPES OF LAMINITIS
- Metabolic/endocrine induced Laminitis– often coupled with Nutritional problems such as a diet too rich in sugars and starch and in the horse with Cushings disease.
- Mechanical Laminitis – this can happen when the horse does not receive regular and appropriate hoof trimming or if the horse is worked on hard surfaces otherwise known as ‘road founder’. This is a result of the lever forces ‘pulling’ the laminar connection apart, when the heels and/or toes are too long.
- Septic Laminitis - seen in brood mares who get septicaemia as a result of retained placenta or in horses following colic surgery.
- Carbohydrate overload Laminitis – when a horse gets a massive carbohydrate hit to the hindgut for example the pony who breaks into the feed room.
- Supporting limb Laminitis – this can happen in a horse with a non-weight bearing injury to one leg, the supporting leg develops laminitis from the stress and strain of taking all the horse’s weight.
The laminae – primary and secondary – are one of nature’s amazingly strong designs. In a healthy hoof the laminae is a tight line of connective tissue, 1 to 2mm wide, which helps hold the internal bone and hoof wall together in a nice conical shape. Its strong and flexible, like Velcro. In an unhealthy hoof, the laminae is stretched - sometimes up to 10mm or more - and the hoof will often have a ‘dished’ appearance. See pictures below:
The broken laminae result in the hoof’s natural integrity breaking down, allowing abscesses and seedy toe to flourish. The breakdown of this connective tissue also results in a lack of support for the pedal bone, which consequently drops down in the hoof capsule (sinks) and ‘rotates’ away from the hoof wall.
A normal pedal bone position on the left shows the bone high in the hoof capsule with a nice tight laminar connection, the pedal bone is parallel to the angle of the hoof wall. The centre picture shows a pedal bone that has rotated away from the bottom half of the hoof wall, the laminar connection has been compromised and has given way. The last picture shows a pedal bone that has sunk in the hoof capsule, often this occurs when a horse sufferers from chronic laminitis. Note in the rotated and the sunk pictures how close the tip of the pedal bone is to the ground, the sole is very thin and this will cause the horse to be very sore. If the condition gets bad enough the bone will penetrate right through the bottom of the foot! This occurrence is extremely painful for the horse and results in the classic founder stance.