EQUINE VETERINARY EDUCATION / AE / FEBRUARY 2018


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can result in lactase deficiency secondary to the loss of small intestinal brush border, supplementation with lactase enzyme may be beneficial in these patients (Weese et al. 1999). Probiotic administration in foals with diarrhoea has become popular although documentation supporting efficacy is lacking.


Nutritional support


Nutritional needs of the foal with diarrhoea depend on several factors including the severity of the diarrhoea, age of the foal, causative agent of the diarrhoea and if there are other systemic factors involved. Foals with mild transient diarrhoea will continue to nurse and be able to maintain proper caloric intake. A neonatal foal with diarrhoea that stops nursing may require nutritional intervention sooner than a suckling foal due to the limitation of body reserves. The presence of other gastrointestinal abnormalities such as ileus or abdominal distention may warrant extra nutrition because the foal is unable to nurse. Foals with profuse watery diarrhoea due to osmotic diarrhoea often suffer from gas accumulation and abdominal distension. In the neonatal foal diarrhoea can be secondary to asphyxia-related gut injuries resulting in mucosal injury and milk intolerance. Failure to provide adequate nutritional support may also have substantial negative influence on the immune response. Nutritional management of the foal with diarrhoea varies


from clinic to clinic. Some practices will completely restrict milk intake of a foal hospitalised with diarrhoea whereas others will allow the foal to continue to nurse. Management of the foal with diarrhoea on the farm often does not allow for restriction of nursing. The effects of these different management practices on morbidity and mortality and long- term outcome are unknown. Prior to developing a nutritional plan the foal must be


triaged and stabilised. Gastrointestinal motility is usually poor if the foal is clinically dehydrated or in shock. Every effort must be made to correct electrolyte, acid-base and hydration status of the case then a nutritional plan can be developed.


Fluids containing dextrose should not be used for initial fluid resuscitation because excessive amounts of dextrose can result in profound hyperglycaemia, although in foals with longstanding diarrhoea or secondary septicaemia, hypoglycaemia is common and some dextrose is required in the initial resuscitation fluid. In these cases 0.25–0.5 ml/kg bwt of a 50% dextrose solution added to the resuscitation fluids is beneficial. Once the foal has been stabilised attention can be given


to determining if there is a need for nutritional support and the best way to go about providing the nutritional support. Neonatal foals that stop nursing or have secondary gastrointestinal problems should be supplemented because of limited energy reserves in the form of glycogen and fat. Profound hypoglycaemia can occur in the neonatal foal if deprived of energy intake even for a few hours (McKenzie and Geor 2009). Suckling foals that stop nursing and are in good body condition may not require supplementation as soon as the neonate, but even after 24–36 h of inappetence benefit from extra calories. The nutritional requirements of a foal with diarrhoea have not been determined. Recommendations are generally based on data from healthy foals. It has been estimated that a healthy neonatal foal’s energy requirement is about 120–150 kcal/kg bwt/day (502–628 kJ/kg bwt/day)


(Martin et al. 1992). In a recent report the resting energy requirements in critically ill neonatal foals was documented to be approximately 50 kcal/kg bwt/day (210 kJ/kg bwt/day), which is about one-third the energy requirements for growing, active normal foals (Jose-Cunilleras et al. 2012). Interestingly, this study also noted that surviving critically ill neonatal foals resting energy requirements normalised to healthy neonatal foal values prior to discharge from the hospital. The energy requirements of a healthy suckling foal are estimated to be 120 kcal/kg bwt/day (502 kJ/kg bwt/day) at 3 weeks of age then 80–100 kcal/kg bwt/day (335–418 kJ/kg bwt/day) at 1 month to weaning (Ousey et al. 1996, 1997). Nutritional supplementation can be provided either enterally or parenterally. The best and most natural is the enteral route, although certain circumstances warrant the parenteral route.


Parenteral nutrition


Parenteral nutrition is indicated for foals with poor gastrointestinal function and intolerance to enteral feeding. The goal of parenteral nutrition is to provide enough nutritional support to avoid energy depletion during a phase of the disease in which enteral nutrition is not an option or provide supplemental nutrition when full enteral nutrition cannot be tolerated. Carbohydrates and lipids are the primary sources of energy used in parenteral nutrition solutions, whereas amino acids are added to meet protein requirements. Carbohydrate-containing fluids solutions represent the


simplest means of providing i.v. nutrition to foals. Supplying energy in the form of dextrose decreases the need for catabolism, which allows the foal’s metabolic energy to be focused on recovery and not on support. The caloric content of a 50% dextrose solution is 1.7 kcal/g (7.1 kJ/g). Carbohydrate-containing solutions can be administered for a short period in the younger foal (24–48 h) and longer in the older foal (3 days) because dextrose-containing fluids are an incomplete nutritional source. The most common solution is a product containing 5% dextrose, which is available in several options including 5% dextrose in water, lactated Ringer’s solution with 5% dextrose, 0.45% saline with 5% dextrose and hypotonic maintenance electrolytes solutions containing 5% dextrose. Alternatively, one can compound a dextrose solution by adding 50% dextrose (500 mg of dextrose/ml) to an isotonic polyionic fluid used for routine fluid support. Although the solution is hypertonic, it can be tolerated for a short term administered at a constant rate infusion. Dextrose in 5% water is not a good choice as a maintenance solution because of the absence of electrolytes and is primarily useful in providing free water to patients suffering from hyperosmolar conditions. A total of 50% dextrose solution can be administered without


dilution using an infusion pump, as long as additional isotonic fluids are being administered concurrently to meet the hydration needs of the case and to avoid endothelial injury


caused by the hypertonic nature of this solution. The primary fluid needs of the case can be met with the isotonic fluids and it will be easier to adjust the fluid rate in response to hydration needs without affecting their nutritional needs. At birth the stimulated fetal liver produces 4–8 mg/kg bwt/min of glucose, thus this is the appropriate rate of the dextrose containing fluids for the neonate, although the really septic neonate may require more (Silver and Comline 1976). The rate similar to an adult, 0.5–2 mg/kg bwt/min, is appropriate for the suckling foal


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