by Karyn B Jules

Created on: September 05, 2009

Laminitis is the breakdown of the folds of tissue, or laminae, which connect the hard outer wall of a horses hoof to the sensitive inner structures. These laminae support and cushion the hoof, protecting it from damage that would otherwise be caused through constant impact with the ground. When the laminae break down in laminitis the whole inner structure of the hoof becomes unstable and blood vessels, nerves and other sensitive tissues press down against each other causing intense pain, heat and inflammation within the hoof. In severe cases of laminitis the pedal bone in the hoof turns and moves downwards to such a degree it can actually pierce through the sole. The exact reason for the breakdown of laminae is still uncertain, and research into hoof structure and health is ongoing. There are, however, known circumstances which can trigger laminitis.

Concussion due to excessive impact on hard surfaces, or extra weight placed on a hoof when a horse is lame and favouring the opposite leg has, in some cases, brought on laminitis. Toxins in the bloodstream either during or following recovery from infections can also cause problems in the hooves. Other less common triggers are certain drugs which may constrict arteries, high levels of stress, and bacterial imbalances in the gut, but by far the greatest percentage of laminitis cases are triggered by the ingestion of an overabundance of lush spring grass.

Spring laminitis, or grass founder as it is commonly known, frequently occurs when horses or ponies are allowed to graze freely on carbohydrate rich, new spring grass after spending the previous nine months of the year on older, less potent, and/or sparse pasture. Horses' natural survival instincts tell them to graze continuously while the going's good, as there are no guarantees in the wild that food will always be available, or of how far the herd will need to travel before they come across adequate feeding grounds again. In domestic situations where an oversupply of good quality grass outweighs the horse's daily requirements, they will eat themselves to obesity if allowed.

Ponies and heavy draught horses are more susceptible to this type of laminitis but other breeds can be affected, particularly if they are already overweight and not in any type of regular exercise routine. A hard neck crest and lumpy fatty appearance over the rump area are definite warning signs of obesity and grass founder is very likely to follow. Once a horse or pony has foundered, even if

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