It does seem to decrease the incidence and severity of the disease in large herd outbreaks. Equine flu is caused by a virus. However, as it takes a month for an animal to recover from flu and be fit enough for vigorous training, the prevention of this disease is critical in competition horses. The vaccine confers immunity for a variable period of time. In some cases, this appears to be as short as three months.
Horses generally contact rabies from a wildlife source, often a bat, skunk, raccoon or fox.
In some areas of the country, wildlife rabies is very common. In horses, infection with rabies causes a wide variety of signs. They, too, may show aggressive behavior, but commonly they demonstrate less specific signs, such as colic, incoordination and lameness. It is very difficult to diagnose rabies in horses based on clinical signs. Consequently, it is very important to vaccinate horses in areas where wildlife rabies is common.