I took the liberty of taking this off another forum as I found it eye-openingly interesting.
I went last night to a laminitis talk by the Barn equine surgery and Andrew Poynton, a specialist farrier. I only took notes on the things I either didn't already know or knew but hadn't really twigged were important.
Shod horses - very little weight bearing on sole or frog - all on the shoe and hoof walls, so all weight suspended on laminae.
Too much grass > toxins in hindgut > toxins in bloodstream generally > toxins in hoof wall > MMP production. (MMP the stuff that destroys the laminae.)
Once it's started, it can't really be stopped. Treatment is about pain relief and providing appropriate conditions for repair. Need new laminae, new hoof growth.
Chronic mild laminitis interrupts the blood flow to the front of the feet over a long period of time. This stunts growth at the front of the hoof and makes the heels grow comparatively faster, which exacerbates the changes in foot balance.
Major risk factor is overweight horse. 50% of the UK's equines are ponies, and 50% of them are overweight.
Highest survival rates in laminitis are those treated with ACP. ACP is a vasodilator so encourages blood flow to the feet and stimulates new hoof growth. Also the sedation is a useful side effect as it discourages movement so minimises firther damage.
Not only lush grass, but poor grass as well. Fast growth is the risk factor with grass.
Strip grazing - if the grass is growing at all, don't move the fence. If you do, then the pony will have access to fast-growing poor grass on the grazed bit and also fast growing lush grass on the new bit.
Other causes - Cushings, insulin resistance (IR), equine metabolic syndrome (EMS).
IR - glucose can't get into the cells where it's meant to be, so it stays in the bloodstream. This has other knock-on effects such as production of corticosteroids, pituitary gland etc.
High blood sugar means that other small events that might otherwise not have been a problem can trigger worse effects inside the hoof wall.
Abdominal fat cells produce their own corticosteroids, which can raise laminitis risk.
IR mainly in ponies. Genetic adaptation to living wild over winter - storing glucose in the blood stream rather than letting it go straight to cells makes it last longer.
Exercise reduces IR, and there is a blood test that can spot it.
Medical treatments aim to treat the primary cause (usually weight), prevent further damage, reduce inflammation, either increase or decrease blood flow to the feet (depending on phase of disease), provide mechanical support and alleviate discomfort.
Cold water treatment (decrease blood flow) only works in the first phase of the disease - before symptoms show. So can be useful as a preventative measure if, for instance, pony has gotten into feed room, or with retained placenta, but only before any symptoms are showing.
Off grass, no treats (sugar) - no apples, carrots, mollassed anything, lickits etc. Stable on a deep bed with small amount of soaked hay while waiting for vet.
Blood flow increases to the feet before clinical signs (see above re: cold water) and then decreases with the acute phase, which is when it starts hurting and horse becomes lame.
Inflammation decreases blood flow as tissues swollen so can't get past it, also increases the enzyme that destroys the laminae.
Balance sedation and painkillers so that horse is comfortable but not running round stable.
Time is of the essence with regards to remedial farriery. The quicker you can get the pedal bone supported and air round the sole to allow the blood flow, the better the chances of recovery.
Lateral balance is as important as the front-back balance - take note of conformation etc to take account of other forces on the foot.
Trimming aims to realign the pedal bone with hoof wall, trim sole and heel.
Ignore the hoof capsule and trim to where the bone is, so x-rays invaluable. This reduces the forces exacerbating any rotation - once bone is rotated you want to get ti back parallel ASAP so the new growing laminae don't have that gap at the bottom prising them apart as they grow.
Once acute phase is over, gentle exercise in moulded soft support shoes (Andrew Poynton's invention) can help stimulate growth and repair.