Osterrieder's preliminary study compared the effectiveness of MLV vaccines to another more widely used vaccine for equine herpes. Owners and veterinarians have been wary of live vaccines because of past incidences in which a previous MLV that was incompletely weakened caused neurological disease symptoms after it was administered. The more widely used type of vaccine, called an inactivated vaccine, employs a killed virus to activate the horse's immune response.
Osterrieder vaccinated five horses with an MLV and five with an inactivated virus; five received no vaccination. None of the 15 horses was pregnant. The horses were then exposed to the herpes virus.
The study found that the horses with MLV vaccinations consistently had lower fevers, no neurological disorders and less virus in nasal fluids. One horse vaccinated with the inactivated virus and one from the control group showed mild neurological symptoms. All the horses, however, have fully recovered.
Osterrieder decided to announce the results of the study prior to peer-reviewed publication because of the recent virus outbreaks. Following the outbreak at Churchill Downs, three barns and some 100 horses were quarantined. The quarantine was fully lifted May 24, when no other horses showed signs of infection.
Eight horses housed at Churchill Downs during the outbreak were cleared to run in the Preakness. However, two horses scheduled in supporting races at the Pimlico Race Course were not allowed to race due to the Churchill Downs quaranti
Source:Cornell University News Service