Enteral feeding in dogs and cats: Indications, principles and techniques (Proceedings)
Introduction and General Principles
Enteral feeding tubes are an essential tool in the provision of nutritional support to animals unable or unwilling to consume sufficient calories on their own1. Nutritional support should be considered for any animal that has been anorexic or has had inadequate voluntary caloric intake for ≥ 3 days, has lost ≥ 10% of their body weight or has other signs of malnutrition (e.g. poor hair coat, muscle wasting, poor wound healing, hypoalbuminemia, lymphopenia)2. Nutritional support should be considered in patient with predisposing conditions such as vomiting, diarrhea or liver disease, prior to development of overt malnutrition3. Pre-emptive feeding tube placement is also recommended in patients where complete or partial anorexia can be expected (e.g. facial or jaw surgery, feline gastrointestinal lymphoma, etc.) and can often be done at the time of general anesthesia for initial therapeutic or diagnostic procedures.
When the gastrointestinal tract is functional, enteral nutrition is usually preferable to parenteral nutrition, as it is a simpler, more economical, has fewer complications and is more physiologically sound2,3. As a starting point, animals are generally supplemented with calories equivalent to their resting energy requirement (RER) each day (RER = (70 x body weight in kg)0.75 )2. Body weight, body condition and tolerance to enteral feeding are carefully monitored to determine if the caloric value of the nutritional plan should be modified2. The volume of commercially available liquid (nasoesophageal and jejunostomy tubes) or blenderized canned diet (esophagostomy and gastrotomy tubes) to be fed each day is calculated. Canned diets (Hill's a/d, Eukanuba Maximum Calorie, Royal Canine Recovery RS) are blenderized with just enough water to ease passage through the tube. The energy density (kcal/mL) of the blended food is equal to the kcal of the unaltered diet divided by the final volume (in mL). The volume (mL/day) of food to be administered per day is equal to the RER (kcal/day) divided by the energy density of the blended food (kcal/mL). Liquid diets (e.g. Clinicare Canine/Feline or RF liquid diet (Abbott Animal Health)) generally need not be diluted, so the volume equivalent to the animals RER is administered each day. Assuming enteral feeding is well tolerated, animals that have been anorexic for more than 3-5 days, should be fed one third of their RER on Day 1, 2/3 of their RER on Day 2 and full RER from Day 3 onwards.Feeding can occur as a continuous infusion (generally liquid diets to hospitalized patients) or as 4-6 bolus feedings per day. Bolus feedings should be warned to body temperature by resting the filled syringe in a warm water bath. For bolus feeding through esophagostomy and gastrotomy tubes, the tube is aspirated with a syringe prior to instillation of food. If residual food is aspirated it is returned to the patient and the volume of the scheduled feeding decreased by an equivalent amount. If residual food volumes are persistent or prevent feeding full RER, promotility agents should be considered (e.g. metoclopramide 0.3 mg/kg PO or via tube 3-4 times per day 30 minutes prior to feeding). A volume of 5-10mL/kg/feeding is usually well tolerated, although animals that were eating normally before tube placement (e.g. post-op facial surgery) or animals that have been chronically tube fed may tolerate slightly larger volumes2. The tube should be flushed with 5-10mL of water after each feeding.
Complications common to enteral feeding techniques in general include tube dislodgement, tube obstruction, aspiration pneumonia and diarrhea4. To prevent obstruction, the tube should be flushed with lukewarm water before and after bolus feedings or medications, intermittently throughout the day for continuous feeding and whenever the tube is aspirated to check for gastric contents or of gastric contents are noted within the tube. Injecting water under gentle pressure will relieve most obstructions4. If unsuccessful, instill carbonated water4 or Coca Cola6 and leave for 1-2 hours (or longer) to digest6. Avoid putting sucralfate through the tube and dissolve all tablet medications completely in water prior to administration through the tube4. Inflammation of the ostomy site, especially in the first few days following placement, is a common complication of esophagostomy, gastrotomy and jejunostomy tubes. Infection of the stoma site is treated with flushing and cleaning of the wound, topical antibacterial ointment and frequent dressing changes4. Persistent leakage or infection of the stoma site requires further investigation. Diarrhea may occur as a result of the primary disease process, the high fat content or osmolality of the diet aconcomitant antibiotic therapy4.