Laminitis (Founder) What is Laminitis (founder)? By Laura Martlock
Reprinted by permission by:TheMane Street (Original Publisher)
In a very basic way, Laminitis, also known as founder, is a problem with the blood flow in the tiny capillaries in the laminae of the hoof. This can be caused by trauma to the hoof (concussion on hard surface), pain from an injury, a tiny little blood clot on the loose, a little swelling in the foot, or a number of chemical imbalances in some distant part of the body caused by retained placenta, or a release of endotoxins as beneficial bacteria in the intestines die off because of a sudden change in their environment. A typical cause of sudden environment change is the sudden influx of simple carbohydrates and sugars in spring grass, or making a sudden switch in the horse's daily feed. The thing is, once there is a little glitch in the blood pressure, the inside of the hoof does not forgive errors. Once the flow of blood through those capallaries is compromised even a tiny bit, the hoof "throws a switch" and creates a shunt that allows the blood to bypass the capillaries and take an easier detour around the laminae. That is what causes the digital pulse you feel so strongly during laminitis. At this point, the laminae are now suffocating. The increase pressure in the capillaries is causing plasma to leak into the free spaces in the foot, and making things even tighter.
This cascade of events begins to accur soon after a horse has a carbohydrate overload (grass or grain) and although a lot of damage is being done on the inside, he will not begin to show the first signs until about 16 hours later. The heart rate goes up, then a few hours later he is mildly lame, maybe as much as 24 hours until distinctive lameness is evident, and it may take as long as a full 40 hours for full blown founder to accur. This is what causes a lot of confusion about the cause of it. However, there are many causes besides carbohydrate overload. Hypothyroidism, selenium deficiency, endotoxemia, Potomac Horse fever, kidney disease, liver disease, infection with Salmonella, ANYTHING that causes a change in the blood flow to the capillaries. (Carbohydrates constricts blood vessels)
Signs of Laminitis
Classic signs of a horse having a laminetic episode are first a "stepping short" way of moving, then a reluctance to move at all. Very quickly, the horse will progress to standing with it's weight rocked back on it's hind feet with the front feet stretched way out in front. This is a very awkward and unusual stance and is quite easily noticed and identified. Normally, a light pulse can be felt above the hoof, but in a foundering horse, the pulse is hard and "bounds" against the fingertips.
Treatment
In all cases of suspected founder, calling the vet immediately is critical to the horse recovering fully. The quicker the series of events going on inside the horse's hoof can be halted, the better the chances for recovery.
Treatments will depend on what started the event. If the problem started in the digestive tract, mineral oil is given by stomach tube to block the absorption of endotoxins and get things moving out faster. There is a hyperimmune endotoxin antiserum that can be given intravenously, costs about $200-$300. Intravenous fluids and antibiotics could be given, too.
Pain-killing antiinflammatory drugs are given because the pain reflex also constricts the capillaries. These help block that response. These drugs are Bute and Banamine. Banamine also has a protective action against endotoxins. Medication is given to incourage circulation in the foot(aspirin and heparin) and Acepromazine and isoxsuprine to dilate the constricted blood vessels and DMSO to reduce inflammation.
Cold hosing is helpful while waiting for the vet, and if the situation is such that it will be a while before the vet gets there, taping wedges under the heels of both front feet will help keep the deep digital flexor tendon from tugging the coffin bone out of place.
Recovery depends entirely on how much damage is done inside the foot. Most of the devastating damage is done within 24 hours, so prompt, aggresive, proper treatment is critical. And, treated properly, even a severely lame horse can recover with virtually no risidual damage. Severe pain does not necessarily mean that perment damage has occured.
Prevention
Prevention is, sometimes, nearly impossible. However, since some things are known to cause certain reactions in a horse's body, these things can be controlled.
Being careful that your horse does not take in too many carbohydrates in the form of spring grass (when stools get loose and bright green, get him off the grass) and preventing access to the grain bin. Proper vaccinations, and proper training methods that don't stress the hooves or the body unduly.
Make any changes to the horse's feeding schedule or the feed itself slowly over a period of time, and feed as little cereal grains as possible.
An overweight horse is more prone to founder. Feeding these horses a chromium/magnesium supplement while eliminating grains and restricting pasture will help them lose weight.
Avoid bedding the horse's stall with hardwood shavings. Shavings made of black walnut and some other hardwoods will introduce toxins into the horse's hoof material.
Prevent overheating during exercise in hot, humid weather if trail riding by riding where there is sure to be available water in the form of running creeks and taking a sponge with you and spongeing the horse at crossings, allowing him to drink his fill whenever he wants to. When riding in the ring, immediately untack and hose the horse off when done.
Limit spring grass in susceptable horses and make sure feed is secured where the horse can't get to it.
The problem with preventing founder or even laminitis, is that it can result from ANY major stress, whether that is diet, illness, fever, injury, mismanagement, overwork, or something inside that is never identified. The most important thing is to talk to your vet about what you can do with your resources to prevent as much damage as possible while the vet gets there.
Laura Martlock - 2004 (c)
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This is an excellent diagram of Laminitis/ threat for Barbaro of healthy limb
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