Comparison of IgG antibody levels to Clostridium botulinum antigens between euthanased and surviving cases of chronic grass sickness

Abstract: Serum from 12 horses suffering from chronic grass sickness (CGS) were assayed for IgG antibodies against botulinum neurotoxins C and D (BoNT/C and BoNT/D) and to a surface antigen extract of a neurotoxin negative strain of Clostridium botulinum type C. Collectively, the six surviving CGS cases demonstrated significantly higher initial IgG levels (P =0.05) against surface antigens than the six that were subsequently euthanased. The surviving animals also demonstrated higher initial IgG levels against the BoNT/C but not reaching significance (P =0.06). The two groups demonstrated no difference between IgG levels against BoNT/D. This study supports existing evidence of the involvement of C. botulinum type C in the aetiology of grass sickness. [Copyright &y& Elsevier]