Grass Sickness still a major threat!


By Dr Jo Ireland BVMS PhD, Cert AVP(EM), MRCVS.

Equine Grass Sickness Research Co-ordinator at the Animal Health Trust.

Equine grass sickness (EGS) is a debilitating disease affecting grazing horses, ponies and donkeys, with a mortality rate in excess of 85%. Since EGS was first recognised in Broughty Ferry during the early 1900s, Britain continues to have the highest incidence worldwide and Scotland remains most severely affected. Despite decades of research, EGS remains a major threat with no methods for prevention currently available. However, the on-going EGS vaccine trial may finally provide a way to reduce the burden of this devastating disease in the future.

The current theory is that EGS is associated with the soil-borne bacterium Clostridium botulinum type C. Previous research found that EGS cases have low antibody levels to this bacterium, while horses with higher antibody levels have a reduced risk. Horses previously in contact

with an EGS case have a lower risk of developing the disease, suggesting some degree of acquired immunity. Therefore the great hope is that, as for other equine clostridial diseases, such as tetanus and botulism, prevention by vaccination should be theoretically possible.

This year the Animal Health Trust launched a nationwide EGS vaccine trial, in collaboration with the EGS Fund and the Universities of Edinburgh, Liverpool and Surrey, designed to test whether vaccinating against Clostridium botulinum can help to prevent the disease, by comparing EGS in vaccinated and placebo-treated groups of  enrolled animals ponies with a valid passport, living on premises that have had at least one  case of EGS in the past three years are eligible to take part.

If shown to be effective, the vaccine would represent the first preventive healthcare measure to reduce  the impact of the disease- a major breakthrough in EGS prevention.

For more information  visit or contact the EGS Vaccine Trial Team – Tel: 01638 -555399

Author: Features Editor

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