University of Liverpool Equine Grass Sickness Research

Miss Helen McCarthy, Dr Christopher Proudman, Dr Nigel French,
Prof. Barrie Edwards and Mr Keith Miller.

'A Case Control Study to investigate the role of
Clostridium botulinum in equine grass sickness'.

A case control study is being conducted to test the hypothesis that equine grass sickness is associated with Clostridium botulinum type III toxicosis.

Exposure to Cl. Botulinum and its C1 neurotoxin is to be assessed in 60 histologically confirmed cases of grass sickness, and 120 controls. In addition to serological evidence of exposure to botulinum toxin, horse-level risk factors are to be evaluated. This study is also testing the hypothesis that pasture level factors are important in grass sickness.

The secondary hypothesis assumes that pasture-level variables are critical in stimulating toxin production and in compromising normal resistance in certain individuals. Pasture-level risk factors will be evaluated by comparison of 60 pastures giving rise to cases, and 120 control premises. Univariable and multivariable techniques will be used to examine the relationships between potential risk factors and grass sickness.

Using a geographical information system, the location and time of diagnosis for each case of grass sickness will be mapped and used to detect and describe the degree of space-time clustering in the Northwest of England. Information from this study will allow the rational formulation of disease diagnosis, treatment and prevention strategies for grass sickness.