Which disease is caused by a virus and can affect horses?

The disease caused by a virus that can affect horses is equine herpes virus-1 (EHV-1). This virus is significant in equine medicine because it leads to a variety of health issues in horses, including respiratory disease, neurological conditions, and abortion in pregnant mares. EHV-1 is highly contagious and can spread rapidly within horse populations. Understanding EHV-1 is crucial for horse owners and veterinarians alike, as managing and preventing outbreaks is essential for equine health.

The other conditions mentioned do not primarily affect horses. Scabies is a parasitic infestation caused by mites, whereas bovine trichomoniasis is a reproductive disease affecting cattle caused by a protozoan parasite, and avian tuberculosis is a bacterial infection that primarily affects birds. Therefore, EHV-1 is the only option that specifically relates to a viral disease affecting horses.