Enteral Supplementation in Neonates
Enteral Support of the Neonate
The enteral route of nutrition is always preferred over parenteral, as enteral feeding has been shown to increase gastrointestinal mass and function compared with the parenteral route.
Small volumes (1% to 2% body weight in 24 hours divided into q2h feedings) are recommended when initiating enteral feeding in foals, particularly if there is concern regarding the health of the gastrointestinal tract. Over time, one can gradually increase the volume fed, paying careful attention to changes in intestinal motility, residual volumes of gastric milk, and signs of colic or diarrhea. An example of a gradual feeding schedule for a sick neonatal foal can be found in Table 50.1.Enteral feeding should be avoided in severely hypotensive or hypothermic neonates. Those with enteropathy, whether secondary to oxygen deprivation or infection, may be unable to absorb nutrients and develop colic and diarrhea when fed. A detailed history and careful repeat assessments of the neonate's gastrointestinal tract (including ultrasound examination if possible) are critical to ensure that the patient can tolerate enteral feedings. Enteral supplementation should be avoided in individuals with a dilated small intestine or ileus or other signs of enteritis. Sequential measurement of abdominal size can be useful to assess gastrointestinal distension and intolerance to feeding. Colic signs in foals are often subtle; foals may appear fussy or agitated and show an increase in heart rate and respiratory rate. If deterioration is noted, enteral feeding should be discontinued or decreased until resolution.
■ TABLE 50.5
Enteral Feeding Schedule for Adult Horses (450-Kg Horse)
Maintenance (1%-1.5%
| Day 1 | Day 1 | Day 2 | Day 3 | Body Weight) |
| Number of meals | 2-3 | 3-4 | 4-6 | 4-6 |
| Complete feed (kg)/meal | 0.5 kg | 0.75 | 0.75-1.0 | 1.0-1.25 |
| Water (L)/meal | 4-6 | 4-6 | 6-8 | 6-8 |
Foals, beef calves, and neonatal small ruminants normally nurse relatively small amounts of milk frequently throughout the day, whereas dairy calves drink larger volumes less frequently.
When foals are fed less frequent meals, hunger may cause them to rapidly ingest larger volumes, overloading the small intestinal ability to digest the nutrients, which can result in bloating, colic, and diarrhea. If this occurs, feeding cold milk may help limit large-volume ingestion. An acidified milk replacer is also available; this product is less likely to become rancid when left out for long periods of time during the warmer season.Generally, a neonate that is too sick to stand is also unlikely to have an adequate suckle reflex. Bottle or syringe feeding is strongly discouraged when supplementing sick or recumbent neonates. These individuals often have a weak or absent suck, putting them at high risk for aspiration. Small soft nasogastric tubes (MILA International Erlanger, Ken.) that may be sutured in place for longer-term use are available for use in foals and have also been used in neonatal calves. Many of these tubes come with a guide wire, which helps stiffen the tube to make insertion easier. Before feeding, it is important to determine if the tube is in the stomach or abomasum. A radiograph can be helpful to identify the radiopaque strip within the tube. Alternatively, tubes can be detected by ultrasound or careful palpation of the esophagus during passage. Alternatively, calves can be fed using esophageal feeders to ensure milk is deposited in the abomasum and not the immature rumen. In neonatal small ruminants, red rubber catheters are often used for esophageal feeding.
When introducing a foal to nurse, it is often beneficial to milk the mare first and feed the foal via the nasogastric tube. This decreases the risk of aspiration due to large-volume let-down by the mare or extreme hunger by the foal. Auscultating the foal's trachea while nursing can help determine if aspiration is occurring. Bucket feeding allows the foal to nurse with its head down, decreasing the risk of aspiration. Once the foal is trained to the bucket, it can be hung in the stall, allowing them to drink at will.
Clinicians should also remember to provide other foodstuffs, as a foal will begin mimicking their dam eating hay and concentrates within the first few days of life.Enteral Feeds for Neonates
Natural species milk and colostrum are ideal enteral feeds for neonates. When mare's milk is limited, supplementing with goat's or cow's milk is generally recommended at least through the early neonatal period (first 2 weeks of life). Many neonatolo- gists prefer goat's milk as a better replacement to mare's milk. Although comparison of the fat, protein, and calories content among goat, sheep, and cow milk does not seem to reveal any significant benefit of one over the other, the major whey protein in both goat and mare milk is β-lactoglobulin, while the major whey protein in cow's milk is α-lactoglobulin.
If necessary, gradual transition from one type of milk or replacer is recommended, as rapid changes may result in colic, diarrhea, or constipation. If constipation develops, a small amount of mineral oil (5 mL) may be added to tube-fed meals. The fluid characteristics of mineral oil make it unsafe to administer orally, as it will not stimulate a cough reflex if aspirated. Even a small amount of aspirated mineral oil can result in significant pulmonary consolidation and dysfunction.
Unlike calves, long-term supplementation of a foal typically requires switching to milk replacers due to cost and accessibility issues of whole milk products. If using a milk replacer, it is strongly recommended to choose a replacer developed for foals rather than one designed for all large animal species to ensure adequate protein, fat, and carbohydrate concentrations. Replacers that contain whey protein are recommended over other protein sources due to digestibility concerns. In contrast to milk replacers, milk is high in potassium and low in sodium and chloride. When feeding milk replacers, it is important to provide a freshwater source to prevent hypernatremia.
Key Points
• Enteral nutrition provides intraluminal nutrition to the gastrointestinal tract and has been shown to improve gut barrier integrity, gut mass, protein content, motility, and function.
• Enteral feeding needs to be increased gradually with careful assessment of gastric residuals before bolus feeding.
• Enteral nutrition can be tailored using complete feeds or specific components diets.