Foals are more likely to get a respiratory disease in their first six months than any other disease. They are more prone to respiratory diseases than adults. In one study, about one-quarter (22.2 percent) of all foals had a respiratory disease. Pneumonia was responsible for most deaths (16 percent) up to six months of age in one study. Foal pneumonia is the major respiratory disease causing economic loss due to death, poor growth and treatment cost. Pneumonia, an inflammation of the lungs, is a common disease in foals of all breeds up to six months of age. A complex disease, pneumonia has many predisposing factors.