With rest, they usually get back to previous form in a couple of weeks. This still represents a lot of lost time, and when a trainer keeps pushing the horse during this time, lasting damage can occur which is even more costly. Another form of the virus causes a paralytic form of rhinopneumonitis. Horses seldom recover from the effects of this form. It is not known whether paralytic cases of herpes are caused by still another variant virus, or whether certain unknown conditions are associated with a herpes infection causing it to settle in the spinal canal.
Most trainers vaccinate for rhinopneumonitis on a regular basis at the track.
In order to be as sure as possible, some trainers vaccinate for rhinopnumonitis every-other month. For many years it was thought that the virus causing virus abortion was the same as the one causing respiratory problems. More recent research, however, has shown that there is a lot of difference in these two strains. So much difference that many experts now believe that different vaccines should be used for these variants of the herpes virus. Curriently in the United States, essentially the same virus is used for vaccines sold to prevent rhinopneumonitis as the vaccine sold to prevent herpes abortion.