Equine grass sickness: serologic evidence of association with Clostridium perfringens type A enterotoxin.

Clostridium perfringens type A enterotoxin seroneutralization was carried out on sera from 50 horses recovered from grass sickness and from 100 other horses with no record of having had the disease. Of the affected horses, 70% had seroneutralizating titers higher than 1:64, half of these being equal or higher than 1:128. More than 88% of the horses with no record of grass sickness had titers lower than 1:64. These data support the theory of association between C perfringens type A toxins and grass sickness.