Not much is known about what causes Grass Sickness and sadly for this reason, as yet there is no known and proven cure.
Grass Sickness is basically damage to the nervous system. It damages the nerves that cause involountary actions. As I said, the cause is unknown but due to the type of damage a sort of toxin is thought to be the cause. The disease occurs almost exclusively in horses with access to grass, hence the name.
I did some research on Grass Sickness a while ago after a horse I knew of came down with it and found some interesting information.
Great Britain has the highest grass sickness occurence in the world but it's also recognised in northern Europe, especially Sweden, Denmark and Germany, with a few cases in France, Belgium, Italy, Holland, Norway and Switzerland. It does not occur in Ireland.
It has been said that mares may be more at risk more then stallions or geldings but it hasn't been proved. It can occur at any age but generally tends to between 2 and 7 years old with a peak at 3 and 4. It can and does occur at any time of the year, but most are seen between April and July with it peaking in May.
There are three forms of grass sickness, subacute, acute and chronic. Although not all horses show all the signs, the major symptom is paralysis from the horses gullet downwards. In the acute strand, symptoms are a lot mroe severe, come up without warning and the horse will often sadly die within 2 days. Muscle tremors and damp sweat patches also come up. Gut paralysis is very serious, it leads to signs of colic, like rolling, looking at flanks, kicking belly, droooling etc. Stomach liquid may start to pour from the nose that smells really rank and they can get constipated.
In subacute, symptoms are similar to acute but are less severe. Horses can have swallowing dificulty, sweating, muscle tremors, quick weight loss and have mild to medium colic. Some die and some may have to be put down within a week, but some move on to chronic.
In chronic grass sickness, the symptoms occur more slowly and only a few cases show mild, intermittent colic. There is some loss of appetite, one major symptom is rapid weight loss which can lead to the horse becoming skin and bone. Horses have been knownto recover from this.
