Caused by a bacteria that invades the upper respiratory tract. It causes abscessation of the lymph nodes, usually in the area of the head and neck. In some animals, the infection may cause abscesses in the lung or gut. Most animals contract strangles as youngsters, and after recovery, are immune for many years. 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.