Diarrhea and septicemia are the greatest disease risks to the foal during the first week of life. Diarrhea during the first week of life can seriously dehydrate a newborn foal, especially if the foal is not nursing enough or the dam is not producing enough milk. Foals that do not receive adequate immunoglobulins from the dam's colostrum are at a high risk for diarrhea. Septicemia, commonly called joint ill or navel ill, is caused by bacteria, or toxins produced by bacteria, in the blood and tissues. It affects the entire body and organs of the foal and is the leading cause of death in newborns.
Foals can contract bacteria in utero or through the umbilical stump, intestinal tract, or lungs.
Septicemia usually occurs within 3 to 4 days of birth, and often the foal shows no noticeable signs until the disease is well advanced. Signs of septicemia are depression, a decrease in nursing activity, diarrhea, and excessive sleeping or resting. Septic foals may have milk on their foreheads, and the mare's udder may be full and hot. Other common health problems in young foals include respiratory infections and pneumonia. A viral or bacterial respiratory infection often weakens the foal so that it is more susceptible to pneumonia-causing organisms.