Equine herpesvirus-8 (EHV-8) appears to have been behind an abortion in a donkey in China, researchers report.
The case is the first in which EHV-8 has been isolated from a donkey in China. Researchers caution that the virus might be one of the primary pathogens that can cause abortion in donkeys.
Nine herpesviruses have been identified that affect the Equidae family, which includes horses, ponies, donkeys and zebras.
EHV-1, EHV-2, EHV-3, EHV-4, and EHV-5 primarily infect the horse, while EHV-6, EHV-7 and EHV-8 are associated with infections in donkeys.
EHV-8 was first isolated in 1988 in the nasal cavity of latently infected donkeys in Australia. It was also identified from a horse with fever and nasal discharge in China and donkeys in Israel.
Until now, EHV-8 has been linked only to respiratory and neurological illness in donkeys, although it has been linked to abortion in horses.
Tongtong Wang, Leyu Hu and their fellow researchers, writing in the Virology Journal, have described the circumstances surrounding an abortion in a four-year-old jenny from a large donkey farm in Liaocheng on the 296th day of pregnancy. The jenny showed signs of a serious respiratory issue.
The unwell donkey had a poor appetite, was sullen, unwilling to move, and a lowered head in the lead-up to her miscarriage.
Examination of the aborted fetus revealed no obvious visible abnormalities except for the lungs, which had a blue/purple tinge.
Tissue specimens from the placenta, umbilical cord, lungs, and liver from the aborted fetus were taken for testing to identify the cause.
Bacteriological and molecular tests were used to screen possible pathogens. Salmonella abortus equi, EHV-1, EHV-4, and equine arteritis virus were all negative.
EHV-8 was the only agent that was isolated and identified, with positive results in the umbilical cord, placenta and lung tissue.
Discussing their findings, the researchers noted that large-scale donkey farms have sprung up around China in recent years.
However, pandemic illnesses have grown year after year because of the extensive breeding of donkeys. Abortions and respiratory illnesses, in particular, have caused significant economic losses in the donkey trade within the country, they said, severely limiting its expansion.
Previous studies have linked abortion in donkeys or horses with several microbes, such as Salmonella abortus equi, Leptospira species, Streptococcus equi subspecies Zooepidemicus, equine arteritis virus, EHV-1, EHV-4, and EHV-8.
In a previous study, Salmonella abortus equi was closely linked with female donkey abortions, although it was not found in this instance.
The findings in the current case suggest that EHV-8 is one of the primary pathogenic agents that cause abortion in female donkeys, the authors said.
Based on their recent work, the positive rate of EHV-8 from large-scale donkey farms in Shandong province might be as high as 25.3 percent, they said.
“As a result, EHV-8 infection in donkey farms should be given more attention, and suitable preventative measures should be explored to reduce EHV-8 infection.”
The study team comprised Tongtong Wang, Yonghui Wang, Wenqiang Liu, Guiqin Liu, Mingxia Zhu, Changfa Wang and Liangliang Li, all with Liaocheng University; Leyu Hu and Huiying Ren, with Qingdao Agricultural University; and Wei Zhang, with the Shandong Academy of Agricultural Sciences.
Wang, T., Hu, L., Wang, Y. et al. Identification of equine herpesvirus 8 in donkey abortion: a case report. Virol J 19, 10 (2022). https://doi.org/10.1186/s12985-021-01738-2