Laminitis (also known as founder) is a condition where the sensitive laminae of the feet become inflamed and swell, causing separation of the tissues. Because the laminae "glue" the pedal bone to the front wall of the hoof and are the main support mechanism of the foot, this separation causes a lot of mechanical problems, including the commonly seen sinking or rotation of the pedal bone down thru the sole. The condition is very painful, and can come on VERY suddenly. It needs prompt veterinary attention. The best thing is to prevent it happening in the first place. To do that you need to know why it occurs. Unfortunately for us it has a lot of different causes.
1) Presence of bacterial toxins, which cause a loss of blood supply to the foot. The resident bacteria in the hindgut can produce these toxins because there is some kind of interference with their normal activity. They can come from an overabundance of the wrong bacteria in the GI tract due to various factors. These undesirable bacteria can grow in the hindgut because too much simple carbohydrate escapes the small intestine (this is what follows when the horse gets into the feed room and overeats grain). These toxins can also be as a result of bacteria dying in the GI tract due to colic or overheating. Another source can be from bacteria growing in the uterus due to retained placenta, or from any kind of massive bacterial overgrowth.
2) Interference in peripheral circulation causing a reduction of blood supply to the hoof capsule and hence a shortage of oxygen and or nutrients to the laminae. The interference of blood supply can be due to insulin resistance (type 2 diabetes), shock from exhaustion, or stress, causing shut down of peripheral circulation, amongst other things.
3) Overdose of corticosteroids, both endogenous (self producing) such as in Cushings disease or stressed horses, and exogenous (overdosing steroids by the vet or others!). One effect of corticosteroids on the system is to reduce peripheral circulation. The horse is particularly sensitive to this.
4) Toxins present in the environment that get into the foot such as when the horse stands on black walnut or other hard wood shavings.
5) A horse with an injury to a limb such that it cannot or will not bear weight on it, can cause the opposite limb to founder due to stress and strain.
There is some current research that shows that Nitric Oxide is a direct messenger for many functions including control of vasodilation (opening of arteries). It is interference or loss of NO that shuts down the circulation to the laminae. Therefore anything that increases NO in the lower leg/foot will help. This can include feeding the appropriate amino acids, applying nitro-glycerin plasters onto the coronary band, using a therapy laser on the coronary band/foot, and pulsating magnetic fields onto the foot capsule.
All of these separately or together can and will reduce the pain and discomfort, halt the death of the laminae and stop the sinking or rotation of the pedal bone if treatment is started soon enough.
FEEDING THE FOUNDERED HORSE
Most founders that are NOT due to toxemia, exhaustion or carrying all the weight on one foot, are the "resistance to insulin" kind. Feed the horse as a diabetic, by giving feeds with low glycemic index. Use a feed high in amino acids, high magnesium (magnesium is used in human diabetics to enhance peripheral circulation), essential fatty acids, minerals etc.
Feeding a foundered or prone-to-founder horse usually means a magnesium/chromium supplement, with or without an amino-acid supplement, and an essential (as in Omega 3) fatty acid supplement. Feed grass hay, possibly a little alfalfa hay, or rinsed sugar beet, BUT stay away from corn, oats, barley, and especially stay away from sugar as molasses. Feed extra fat in the form of oil or rice bran if you need to get energy into the horse.
The pre-Cushinoid horse (usually insulin resistant) will also benefit from a supplement high in magnesium and chromium.
Post founder, feed a feed that will support hoof growth without excess carbohydrates. This means the best possible blend of amino acids and essential fatty acids, with a good supply of digestible minerals and vitamins.
Preventing founder is done best by constant vigilance over the quality of the feed, and the body score of the horse.
Overweight horses are more prone, so keep their weight down. If they are overweight feed a magnesium/chromium supplement and reduce or eliminate their grain so that they lose weight.
Don't overfeed carbohydrates (grain).
Check the placenta on all foaling mares, to make sure it is intact. If a bit is missing, call the vet!
Keep the feed room securely shut to prevent unauthorized invasions.
Don't overdose steroids.
In spring, keep susceptible horses off the fresh grass by limiting their grazing time.
Prevent or treat horses overheating from exercise or fever as quickly as possible.
Avoid hardwood shavings in the bedding.
If the horse has an injury to one limb such that it bears no weight on it, support the other limb(s) with wraps or boots so that they get
Dr. Melyni Worth is an Equine Nutrition Consultant Visit her website at www.foxdenequine.com