Enteral Nutrition: Tube Feeding

Craig Datz, DVM, MS, DABVP (Canine & Feline), DACVN, University of Missouri

Allison Wara, DVM, University of Missouri College of Veterinary Medicine

ArticleLast Updated November 20144 min readPeer Reviewed
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What diets can be fed to dogs and cats via enteral feeding tubes, and how should they be administered?

Assisted feeding is a procedure used to supply nutrition to animals that are not eating voluntarily. Tube feeding, also called enteral nutrition, is becoming more widespread because of the increased availability of specialty and 24-hour hospitals, greater selection of diets and techniques, and improved patient outcomes; several studies indicate it can result in lower patient morbidity and mortality, as well as shorter hospital stays.1

Feeding Tubes

The most common types of feeding tubes are nasoesophageal or nasogastric (NE, NG), esophagostomy (E), gastrostomy (PEG or G), and jejunostomy (J). Liquid enteral diets are used for NE, NG, and J tubes because of their narrow diameter (5- or 8-French). For larger feeding tubes (E and G tubes, 12–24 French), other diets may be used provided they are properly prepared. 

The following provides an overview on selecting types and calculating amounts of diets for E- and G-tube assisted feeding.

Diet Selection

Several critical care diets can be fed directly through large feeding tubes or after diluting with small amounts of water. Compared with maintenance diets, they are relatively high in protein and fat and low in carbohydrates. Patients may require different types of diets depending on their medical condition; for example, a cat with kidney disease may benefit from a diet restricted in protein and phosphorus, whereas a dog with acute pancreatitis might need a diet restricted in fat. Likewise, puppies and kittens require diets formulated for growth. Selection is not limited to critical care diets; almost all canned diets can be prepared and fed through larger feeding tubes. 

How Much & How Often?

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The first step is to calculate the patient’s daily resting energy requirement (RER) at current body weight (BW; see RER Calculation). If the patient is obese (>20% above ideal BW), then RER may be calculated at ideal or target weight.2 Multiples of RER (illness factors) are no longer recommended because of the risk for complications from overfeeding.3

The second step is to determine how many times per day the patient will be tube-fed (eg, 4–6 feedings). The RER (kcal/d) is divided by the number of feedings for the kcal/feeding. The final step is to divide the kcal/feeding by the kcal/mL of the diet for the number of mL/feeding (see Example Feeding Plan).

Overfeeding or rapid reintroduction of enteral nutrition may lead to vomiting, diarrhea, and/or discomfort. In rare cases, this can lead to refeeding syndrome, which can result in sudden hypokalemia, hypophosphatemia, and hypomagnesemia. For patients with prolonged history of anorexia (eg, starvation, hepatic lipidosis) that are at risk for refeeding syndrome, a longer, slower ramp-up may be needed. On day 1, 25% to 33% of the daily RER can be given. On day 2, this amount can be increased to 50% to 67% RER; on day 3, 75% to 100% RER; and on day 4 and beyond, 100% RER until the patient resumes voluntary food intake.4 Most animals with E- and G-tubes do well with 3 to 6 feedings per day. Feeding once or twice per day is often not tolerated because of volume overload.

Preparing Canned Diets for Tube Feeding

After an appropriate diet is selected for the patient’s needs, it must be diluted and mixed sufficiently to form a slurry or liquefied diet (see Enteral Nutrition: Step-by-Step).

To determine the kcal/mL of the slurry, the product weight in grams (g/can) and the kcal/can of the diet must first be determined. This information may be printed on the product label, but the company, feeding guide, or website may need to be consulted. The next step is to determine how much water will be added to ensure an adequate consistency of the slurry. The number of grams of diet and number of mL of water are then added together (or the final volume of the slurry is determined in mL). Finally, the kcal/can can be divided by the total mL to determine the kcal/mL.

Conclusion

Tube feeding is an effective method of providing nutrition to sick and injured patients that are unable to voluntarily consume sufficient amounts or types of food. It is important to calculate the amount to feed per day using the RER equation, and it is equally important to determine the kcal/mL of the slurry administered so that appropriate feeding instructions can be written and followed.