Serological and microbiological findings on 3 farms with equine leptospiral abortions.

This study focuses on examining the presence and effect of leptospira, a type of bacteria associated with abortions in horses, in three horse farms with previous occurrences of leptospiral abortions in Central Kentucky.

Study Methodology

• The research utilized blood and urine samples from horses in three equine farms in Central Kentucky, previously known to have cases of leptospiral abortions.
• All horses available on each farm were subjected to blood sampling, which was then tested for antibodies to six different serovars (varieties or strains of leptospira).
• Non-pregnant mares that exhibited high serum antibody levels were selected for urine sampling. The urine samples were assessed for the presence of leptospires using dark-field microscopy, fluorescent antibody testing, and culture.

Findings

• The study depicted that adult horses illustrated the highest serological exposure to leptospira, followed by yearlings and then foals.
• Of the horses with anti-leptospiral antibodies, majority reacted against bratislava serovar, followed by icterohaemorrhagiae. Less reactiveness was found against grippotyphosa, pomona genotype kennewicki, hardjo, and canicola serovars.
• This result confirmed prior assumptions that horses in central Kentucky are exposed to a variety of leptospira serovars.
• The prevalence of antibodies to the six selected serovars remained consistent across the three farms involved in the study.

Implications

• The study found no direct correlation between the serovar causing abortion in the previous season and the prevalence of positive titres for the same serovar in horses tested in the following year.
• This suggests that the presence of serovar-specific antibodies does not necessarily predict the risk of abortion caused by the same serovar.
• Moreover, the study could not find evidence of long-term urinary shedding of leptospira among horses with high leptospira antibody titres. This implies that the urinary presence of leptospira does not necessarily correlate with high antibody levels in the bloodstream.