April, May and June are the peak months for cases of this dreadful disease. We wanted to use our website to warn horse owners about the condition as there have been a number of cases seen recently.

What is this disease “Equine Grass Sickness?”
Equine grass sickness (EGS) is a disease of the nerves that co-ordinate intestinal movement. It is now thought that the disease is caused by toxins released from the bacteria Clostridium botulinum that damage these and other nerves throughout the horse’s  body. The signs of disease shown by horses with EGS reflect this damage to the nervous system. Grass sickness occurs in several different forms, ranging from acute to chronic. The sudden-onset (acute) form of the disease is characterised by signs of colic. In fact, it is sometimes very difficult to differentiate this cause of colic from the many other types of intestinal problem that are classed as “colic.” The chronic type of EGS is much slower in onset and takes the form of progressive weight loss. Over a period of up to two weeks horses become thinner with a markedly “tucked-up” abdomen. Some people describe this as a “greyhound” appearance. Horses affected by this slower onset (chronic) form of disease become very depressed and have difficulty eating food.

Practical advice to decrease the risk of EGS in your horses:
This advice is particularly relevant to the owners of horse on “high risk” premises i.e. premises that have recently given rise to a case of EGS.
• Avoid grazing young horses (less than 7 years old) on high risk premises if possible. Young horses are most at risk from EGS. Older horses are less likely to suffer from the disease.
• Avoid changes in management during the high risk spring period (April-June). This includes moving horses to different pastures, buying new horses from other areas, and changes in diet. Recent change in diet is one of the biggest risk factors for EGS.
• Supplement the diet of horses “at risk” with extra hay or haylage throughout the spring.
• Avoid digging up or otherwise disturbing the soil. Do not dig holes for fence posts, trenches for drains or foundations for buildings in the pastures of grazing horses. Mechanical removal of droppings is also best avoided.
• Avoid the intensive use of worming drugs in the months leading up to the high risk spring period. Worm control is obviously important but the over-use of worming drugs may increase the risk of EGS. Talk to one of our vets about getting the balance right.
• Don’t worry about ploughing and re-seeding pasture or about the use of nitrogen fertilizer. Neither of these has been demonstrated to change the risk of EGS.

Practical advice on what to do if a horse on the same premises is affected by EGS:
Equine grass sickness shows marked clustering in time and space. In other words, when a horse on particular premises is diagnosed with the disease, there is an increased risk of other horses close-by also suffering the disease for a period of approximately one month. The radius of increased risk is at least 10km but there is likely to be a gradient of risk; risk is highest on the affected premises and decreases with distance from those premises.

Until the exact cause is known, it is difficult to give sound advice regarding prevention. In areas where the disease is prevalent, stabling the animals during the spring and early summer will reduce the likelihood of disease. Following the discovery of an association with weather, some owners living in affected areas now stable their horses when dry weather with a temperature of 7-11°C has persisted for 10 consecutive days. Stabling is particularly advisable for a new horse that has been moved onto premises where the disease is known to occur. If certain fields are “bad” for the disease, they can be grazed by other stock, especially in spring and summer.

If a case occurs amongst a group of horses, it is probably best to move the others out of that field provided this does not involve too much stress associated with transportation or mixing with strange horses. If horses cannot be moved from the pasture then supplementary feeding with hay, haylage or hard feed may reduce the amount of grass the horses eat. It has been suggested that feeding haylage to grazing horses may have a protective effect. …and FINALLY please watch out for laminitis , which is the other disease we see too much of at this time of year in our horses and ponies turned out on the Spring grass and in a way can be considered another sort of grass related illness!

If you have any queries, please do not hesitate to contact us, on the main office number 01622 813700.