Nutritional Support for Sick Neonatal Foals

Harold McKenzie III, DVM, MS, Dipl. ACVIM, assistant professor in equine medicine at the Marion duPont Scott Equine Medical Center in Leesburg, Va., discussed the challenge of providing nutritional support to sick neonatal foals in his presentation at the 2007 American Association of Equine Practitioners Convention, held Dec. 1-5 in Orlando, Fla. Many factors need to be considered--a foal's energy requirements, his ability to digest and metabolize nutrients, the changing quality of the mare's milk, and the ability to monitor the sick foal. McKenzie notes that some disease processes might have begun before birth. To implement a useful nutritional strategy, McKenzie believes it is helpful to first understand nutrient demands of a healthy foal.

A foal's nutritional plan depends on his stage of growth and energy metabolism. It is possible for hypoglycemia (low blood sugar) to occur even in a healthy neonatal foal due to limited residual energy supplies as the neonate transitions from the womb and maternal energy sources to ingestion of energy from milk. With that in mind, a sick foal can experience profound hypoglycemia within even a few hours of limited or absent energy intake.

A healthy, growing foal must maintain growth at the rate of 2½% of body weight each day, and he also needs calories to support basal metabolic rate. As a foal's body weight increases, his total calorie requirements increase, and the pancreas must secrete sufficient insulin to enable utilization of ample carbohydrates obtained from mare's milk. Studies have shown that mares fed a diet high in soluble carbohydrates in late gestation might contribute to a decrease in insulin sensitivity in 5½-month-old foals, and this is undesirable because it might potentially create hormonal imbalances later in life. McKenzie explains that there might be some "prenatal programming" effect that could play a role in development of adult metabolic disease.

A premature foal has additional issues--he might not have experienced normal hormonal maturation signals and, thus, could be impaired in metabolic regulation tasks, leading to hypoglycemia, weakness, depression, and an inability to stand. Insulin resistance might render a premature foal unable to utilize carbohydrates that are administered by stomach tube or intravenously, so he might become hyperglycemic (high blood sugar), particularly if septic. Such an individual might need lipid-based supplementation for calories. Because the critically ill neonate can experience some insulin resistance, he could require administration of insulin coupled with hourly monitoring of blood glucose.


A sick foal might only require one-third the energy that an active and healthy foal requires.

The amount of necessary caloric intake for a sick neonate was once thought to be extremely high, but it appears that with less activity and a slowed growth rate that results from illness, a sick foal might only require one-third the energy that an active and healthy foal requires. (Daily milk intake of a normal neonatal foal is 20-22% of body weight.) McKenzie suggests that it might be better to underfeed calories to a critically ill neonatal foal, since feeding too much nutrition exerts adverse effects, including raising carbon dioxide levels, elevating blood glucose, increasing protein catabolism (breakdown to simpler compounds), and leading to azotemia (a toxic condition where nitrogen-type wastes such as blood urea nitrogen--BUN--and urea appear in the bloodstream). In humans insufficient caloric intake for the short term did not result in a worsened outcome and has been associated with fewer complications.

Feed supplementation in healthy or sick foals is best achieved with mare's milk, either with a bottle, bowl, or by stomach tube. A sick foal often has a poor suckle reflex, however, so he might require a feeding tube. Placement of a small-bore, indwelling tube eliminates the stress of multiple tube passages; milk is infused through the tube by gravity flow. A foal that is supplied nutrients by feeding tube should be monitored for overdistention of the stomach or bowels and for decreased intestinal motility. Intravenous supplementation with electrolyte solutions and dextrose can also provide nutritional supportive care.

A foal that is affected by gastrointestinal disease might not be a candidate for a feeding tube and will require parenteral nutrition (energy and amino acid solutions given by way of a method besides the gastrointestinal tract) by intravenous infusion with an infusion pump. This technique is expensive and does have a risk of secondary complications such as thrombophlebitis (inflammation of the jugular vein), infection, hyperglycemia, and hypertriglyceridemia (elevated levels of triglycerides, which are a component of fat). The objective of parenteral nutrition is to supply sufficient calories for basic metabolic needs and for growth, and it should support the immune system. Careful monitoring is necessary, particularly of body weight, rectal temperature, blood glucose, urine output, and of the respiratory and neurologic systems. Despite these concerns, McKenzie stresses that parenteral nutrition can be invaluable in the support of sick foals.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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