An outbreak of equine virus abortion in California.

This research article documents an equine virus abortion outbreak at a California Thoroughbred stud. The researchers investigated the cause of the disease, confirming it to be the equine virus abortion through the discovery of specific abnormalities in the tissue of aborted foal livers.

Details about the Outbreak

• The article reports an outbreak of equine virus abortion at a Thoroughbred stud in California, a disease which is commonly associated with Kentucky, making this an interesting case.
• The stud had not previously experienced equine abortions, although there had been some incidents of nonconception sterility.
• At the time this particular outbreak was investigated, five mares had aborted foals after carrying the pregnancy for between 270 and 830 days.
• A total of sixteen resident mares, bred with two stallions, were involved in the outbreak.

Investigation and Findings

• Investigation into the issue revealed that the abortions were not exclusive to mares bred with either stallion, suggesting the disease wasn’t limited to a specific lineage.
• There were also five additional boarder mares present for stud services during the outbreak, one of which aborted during her short stay.
• All the mares had previously tested negative for Salmonella.
• Feeding practices were also found to be good and hence, ruled out as a potential cause.
• Five more abortions were reported in the ten days post investigation initiation.
• Autopsies of the aborted foals showed similar symptoms including increased intra-thoracic and intra-abdominal fluid, subepicardial hemorrhages, and, in two cases, pin-point focal necrosis of the liver.
• Bacteriological cultures conducted on various body parts and waste from the foals did not yield any significant pathogens.

Confirmation of the Disease

• The symptoms combined with the exclusion of other potential causes led the researchers to consider virus abortion infection as a possible explanation.
• The disease was confirmed by the discovery of acidophilic intranuclear inclusion bodies within the liver cells of the aborted foetuses, which is considered a diagnostic characteristic of equine virus abortion.
• Further to confirm, two pregnant mares were inoculated with a solution containing tissue samples from the aborted foetuses these mares later aborted, with their foetuses displaying the same inclusion bodies in their livers.