[Three cases of virus isolation from horse fetuses diagnosed with equine arteritis virus (EAV) abortion from stud farms with different breeds].

The study investigated three cases of equine abortion caused by the Equine Arteritis Virus (EAV), occurring at stud farms with distinct horse breeds; Icelandic ponies, Warmbloods, and Lipizzaner horses. The study also looked into EAV’s introduction and persistence in the studs, its source, and the potential role of preexisting antibodies in preventing further abortions.

Investigation of EAV abortion cases

• The researchers isolated and typed EAV from the fetuses of the aborted horses, diagnosing the cause of the abortions as EAV.
• All three cases were single instances and occurred in studs where only one breed of horses was kept, suggesting no epidemiologic link between the cases.

EAV Introduction and Persistence

• Seroneutralization tests performed on horses that were in contact with the aborted fetuses showed that the virus had been recently introduced into the stud with the Iceland Ponies, most likely by an extraneous mare that was temporarily stabled for covering by the stud’s stallion.
• Post-abortion serology tests showed that the virus had been present in the Warmblood stud for a longer period, indicating a sustained infection.
• The Lipizzaner stud was also found to have been persistently infected. This was discovered by testing pre-abortion serums stored at the institute.

Role of preexisting antibodies and source of EAV

• It was revealed that preexisting neutralizing antibodies at the Warmblood and Lipizzaner studs accounted for the single abortion case at each stud and helped prevent serial abortions.
• By examining frozen serums from previous years, it was established that Lipizzaner stallions had been reacting positively to EAV for several years. However, the gestation period of the aborting mare ruled out EAV-positive semen transmitted during copulation as a reason for the abortion.
• The study concluded that neither the Iceland Pony stallion nor the Warmblood stallion was linked to the infections as they were persistently seronegative.