Grass Sickness

Grass sickness is a disease which is seen in horses, donkeys and ponies and is thought to be due to the eating of toxins which are present in grass. The disease causes damage to the nervous system and this leads ultimately to the main symptom of gut paralysis.

Grass sickness can occue in horses at any age but the greatest number of cases occur in two to seven year olds however it is not known why this is the case.

Many people think that high nitrogen levels and soil disturbance could be contributing factors for the disease, as well as the presence of Clostridium botulinum which is a soil associated bacterium.

Grass sickness occurs in three forms. Acute, Subacute and chronic. The major symptoms are partial or total paralysis of the digestive tract. With acute grass sickness the horse will die or be required to be put down within two days of the onset of the disease. The vet that I was with told me that severe gut paralysis can lead to signs of colic, with the horse rolling, looking at the flanks, drooling and pawing at the ground.

With the acute disease, the stomach may become distended with foul smelling liquid which can, in cases, pour down the nose. There is also sweating and muscle tremors.

The horse that I was seeing with the vet was suffering from chronic grass sickness and as such had lost large amounts of weight and was now extremely thin. This was evident in the clearly protruding ribs and thin neck. The owner said that this weight had been lost in a week of onset. The horse was finding it hard to swallow and so could not eat particualrly well, but, positively he was still eating which with this disease is always a good sign.

The vet told the owner to ensure that the horse was getting a food which was high in energy, and this was already being done, in this case high energy concentrates with molasses was being given and continual human stimulation is extremely important with grooming regularly a essential part of this to prevent the coat from becoming wet and sticky with sweat.

This treatment will have to continue for long periods of time allowing the horse to gain weight once more and requires large amounts of time; in many cases really encouraging the horse to eat. If the horse is doing well after a period of about 6-8 weeks after the onset then there is a very good chance of survival and relapses are very rare, but it does not nessessarily mean that the horse will survive.

It is important to remember that the welfare of the animal must always be kept in mind. Is it right to carry on treating the animal if we know that the chances of its survival are already low and it is in pain? These are all questions which a vet in practise must regularly address, whether it is with equine, farm or small animals.