Death most commonly occurs due to a secondary infection causing pneumonia. While uncommon, it is usually fatal. Treatment depends on the stage of the disease. A veterinarian can take nasal swabs to confirm that the horse is not shedding streptococcus equi. However, because the bacteria can be shed sporadically, a total of three nasal swabs over a period of seven days are required to assure that the horse is negative.
Vaccinations are another useful control.
Although current vaccines are more effective and cause less reaction than those of the past, they do not always prevent the disease. Still, the severity of the disease is lessened if the horse has received the inoculation. This cannot happen since the vaccine is made from only parts of the bacteria. There is no evidence to support this belief. These animals still need to be isolated to stop further spread of the disease.