A string of abortions that affected a state horse stud in China early last year was probably caused by the equine herpesirus-1 (EHV-1) virus, researchers report.
In January 2021, the Chinese State Studs of Zhaosu, in North Xinjiang, saw abortions in 43 out of 800 pregnant Yili horses without any additional clinical signs.
They were part of a population comprising 20 Thoroughbred stallions and 800 mares aged four years or older. The mares were all about six months pregnant.
Panpan Tong, Ruli Duan, Nuerlan Palidan and their fellow researchers, writing in the journal BMC Veterinary Research, set out to investigate whether a virus was the cause. They took samples of lung tissue from all the aborted fetuses, using molecular-based methods to test for the presence of EHV-1, EHV-2, EHV-4 and EHV-5.
Testing revealed the presence of EHV-1 in all 43 samples. Some of the mares had co-infections with a second equine herpesvirus: In addition to EHV-1, EHV-4 was detected in one sample, EHV-2 in three samples, and EHV-5 in seven samples.
In several cases, more than two equine herpesviruses were detected. For example, co-infection with EHV-1, EHV-4 and EHV-5 was detected in one sample, while co-infection with EHV-1, EHV-2 and EHV-5 was detected in three samples.
The results, they said, pointed to EHV-1 being the cause of the abortion storm. Additional analysis showed that the EHV-1 was the neuropathogenic strain – a form capable of causing neurological problems.
The researchers in the Xinjiang Agricultural University study said their work was the first to establish EHV-1 as the cause of abortions in Yili horses.
Discussing their findings, the researchers noted that EHV-4 is known to cause sporadic abortions, but it has not yet been shown whether EHV-2 and EHV-5 are also a cause for concern.
They said they expected their study will create awareness about the role of neuropathogenic EHV-1 in horse abortions in China, and promote the development of vaccines against the virus.
The study team comprised Tong, Duan, Palidan, Haifeng Deng, Liya Duan, Meiling Ren, Xiaozhen Song, Chenyang Jia, Shuyao Tian, Enhui Yang, Ling Kuang and Jinxin Xie.
Tong, P., Duan, R., Palidan, N. et al. Outbreak of neuropathogenic equid herpesvirus 1 causing abortions in Yili horses of Zhaosu, North Xinjiang, China. BMC Vet Res 18, 83 (2022). https://doi.org/10.1186/s12917-022-03171-1
The study, published under a Creative Commons Licensecan be read here.