Early feeding of hospitalized veterinary patients is critical for prevention of malnutrition and recovery from systemic illness. Enteral nutrition may be preferred to parenteral nutrition when there is adequate GI tract function. Enteral nutrition helps maintain the structure and function of the GI tract and acts as an immunologic barrier. Recovery from such conditions as parvoviral enteritis is faster with enteral nutrition.¹ Patients should be given a chance to eat on their own before tube feeding is initiated.

Enteral nutrition is commonly delivered via a nasoesophageal (NE), nasogastric (NG), esophagostomy, gastrostomy, or enterostomy tube. NE and NG feeding tubes are relatively inexpensive, can be placed quickly and easily, do not require general anesthesia, and are generally well tolerated by cats and dogs (Figure 1). The small tube size allows patients to eat or drink around the tubes. Although NE and NG tubes are normally used for short-term feeding, they can be retained for several weeks²; however, unlike gastrostomy and enterostomy tubes, NE and NG tubes can be removed within hours of placement. Evidence that NG tubes can cause signs of reflux esophagitis is lacking (possibly because of their small size), despite the fact that they cross the lower esophageal sphincter.^3,4

Related Article: Feeding the Critically Ill, Anorectic Dog

Care & Considerations
The small internal diameter of NE and NG tubes is a major limitation. When a 5- or 6-French tube is placed, supplementation is limited to a liquid enteral diet. If they can be used, larger tubes can accommodate a diluted, commercially homogenized recovery diet. Liquid diets can be delivered via constant-rate infusion (CRI) or intermittent bolus (see Developing a Feeding Plan). If a syringe pump is used for CRI, the fluid line should be changed daily to prevent clogging.

If bolus delivery is elected, the tube should be aspirated between feedings to confirm tube patency, GI motility, and adequate passage of the previous meal. If more than 20% of the previous meal is aspirated, prokinetic drug administration and reduced food intake are recommended. The diet should be warmed to near body temperature and slowly administered over 10 to 15 minutes. If vomiting, hypersalivation, or abdominal distention occurs during infusion, the volume and infusion rate should be decreased and feeding frequency increased. To prevent occlusion between feedings, the tube should be flushed and capped with a column of water remaining.

Contraindications & Complications
NE and NG tubes should not be placed in patients that are comatose, laterally recumbent, or dyspneic; lack a gag reflex; or have esophageal dysfunction or obstruction. Tubes should be placed with caution in patients with thrombocytopenia or coagulopathies to avoid uncontrollable nasal bleeding. Although vomiting sometimes contraindicates their use, NE and NG tubes have been successfully placed in vomiting patients; vomiting may be significantly reduced with NE or NG tube feeding.^1,3

Potential complications of NE and NG tube placement and feeding include epistaxis, hypersalivation, vomiting, diarrhea, dacryocystitis, tube obstruction, or inadvertent tube dislodgement.

Related Article: How To Place An Esophagostomy Tube

Figure 2. Inadvertent placement of an NG tube in the trachea and bronchus of a miniature dachshund (11 years of age). This dog had a severe pulmonary interstitial pattern secondary to infusion of 20 mL of sterile saline through the tube; it had no cough reflex during infusion (A). After injection of 3 mL of iohexol 240, positive contrast medium outlined the alveoli, particularly in the caudodorsal thorax, confirming tube misplacement (B). The following day, radiography confirmed that contrast medium and saline had been cleared from the lungs.

Figure 3. Although this tube terminates in the esophagus, tube coiling in the nasopharynx and oropharynx will likely cause coughing or vomiting and subsequent oral expulsion of the tube end.

Developing a Feeding Plan

Calculate resting energy requirement (RER) for the patient’s current or ideal weight (if obese).

• For accuracy, use the formula: RER (kcal/day) = 70 × [body weight (kg)]^0.75
• RER may need to be adjusted to address underlying disease and is often multiplied by a factor of 1.25 to meet increased caloric requirements.

If the patient is neither drinking nor on IV fluids, calculate fluid requirements.

• Daily mL of required water is approximately the same number as the daily RER kcal.

Feed one-fourth to one-third of nutritional requirements on day 1; deliver via CRI or in 6–8 feedings.

• If there is risk for refeeding syndrome (see Author Insight), check electrolytes within 24 hours of initial feedings.

Gradually increase volume and decrease frequency of feeding so the patient is receiving 100% of nutritional requirements in 3–4 feedings, or with CRI, by day 3 or 4.

What You Will Need

• Sedative ± analgesic (eg, opioid) and local anesthetic
• 0.5% proparacaine hydrochloride or 2% lidocaine hydrochloride solution
• Water-based lubricant or 2% lidocaine gel
• 5-, 6-, or 8-French radiopaque polyurethane or silicone elastomer tube
• Skin marker
• 1-inch, white tape
• Skin stapler or 3-0 nylon suture on a straight needle
• Super or tissue glue (optional)
• 6-mL syringe
• 3–5 mL of sterile saline
• Elizabethan collar
• Nonionic radiographic contrast medium (eg, iohexol) or end-tidal CO₂ monitor

Step-by-Step: Nasoesophageal or Nasogastric Feeding Tube Placement

Author Insight: Anorectic patients receiving enteral feedings should be monitored for dramatic decreases in phosphate, magnesium, and potassium levels, which are clinicopathologic abnormalities associated with a rare metabolic disorder known as refeeding syndrome. Refeeding syndrome can result in hematologic, neuromuscular, neurologic, pulmonary, and cardiovascular complications and death.

Author Insight: Premedicating both nostrils allows immediate passage into either of the nares once the anesthetic has taken effect.

In cats, insert the tube in the medial aspect of either of the nares (B), and direct it caudoventrally.

Step 4. Advance the tube steadily into the nasopharynx. If there is resistance, withdraw the tube and redirect it ventrally to avoid the ethmoid turbinates. Hold the head in a normal position and allow the patient to swallow the tube.

Figure 4. Sagittal CT image of the nasal cavity of a dog. Arrowheads illustrate the path the tube must take. The tube must pass over the incisive bone and roots of the incisors before it can be directed through the ventral meatus, ventral to the ventral nasal concha (arrow) and ethmoid turbinates.

In dogs, use suture (± tissue glue) or skin staples to secure the tube near or along the nasal planum (A). At a point level with the forehead (dogs or cats) or the buccal pouch on the lateral face (dogs), place butterfly tape on the tube and staple or suture the tape to the skin (B). Place an Elizabethan collar and secure the tube on the neck under and behind the collar.

Author Insight: If a finger trap pattern is used, several drops of tissue glue can be placed along the suture to prevent slippage when the tube becomes wet (A).

Step 6. Confirm initial tube placement by suctioning to verify presence of negative pressure, flushing with 3–5 mL of sterile saline and listening for a cough, or attaching the tube to an end-tidal CO2 monitor.

Verify tube location with survey (A) or contrast (B) radiography. Inject 2–3 mL of iohexol or other nonionic, iodinated contrast medium into the tube, followed by 3–5 mL of air or sterile saline. Note how the contrast medium highlights the esophageal folds.

Figure 6. In this dog, the proximal end of the tube is not associated with the trachea.

Author Insight: When an NE tube is placed appropriately, its end is located at the eighth intercostal space (approximately). Even properly placed tubes can appear to be in the airways, because the esophagus overlies the trachea and bronchi on caudal cervical and thoracic radiographs.

KATHLEEN AICHER, DVM, is a resident in small animal internal medicine at North Carolina State University. Her interests include GI, hepatobiliary, and infectious diseases. Dr. Aicher completed a rotating small animal internship at University of Tennessee and earned her DVM from Texas A&M University.

BRIAN ALLETT, DVM, is a resident in radiology at University of Tennessee. He completed a small animal internship with emphases on internal and emergency medicine. Dr. Allett practiced as an emergency veterinarian at small animal specialty and referral practices in California before returning to the university setting. He earned his DVM from Ross University.

KAREN M. TOBIAS, DVM, MS, DACVS, is professor of small animal surgery at University of Tennessee. She taught at University of Georgia and Washington State University and authored Manual of Small Animal Soft Tissue Surgery. Dr. Tobias was coeditor of Veterinary Surgery: Small Animal. She completed an internship and residency at Purdue University and The Ohio State University, respectively, and earned her DVM from University of Illinois. Dr. Tobias presented on essential wound care techniques at the NAVC Conference 2013.

 NASOESOPHAGEAL & NASOGASTRIC TUBE PLACEMENT • Kathleen Aicher, Karen M. Tobias, & Brian Allett

References

1. Effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in dogs with severe parvoviral enteritis. Mohr AJ, Leisewitz AL, Jacobson LS, et al. JVIM 17:791- 798, 2003.
2. Continuous versus intermittent delivery of nutrition via nasoenteric feeding tubes in hospitalized canine and feline patients: 91 patients (2002-2007). Campbell JA, Jutkowitz LA, Santoro KA, et al. JVECC 20:232-236, 2010.
3. Nasogastric tube feeding in cats with suspected acute pancreatitis: 55 cases (2001-2006). Claus JA, Rudloff E, Kirby R. JVECC 19:337-346, 2009.
4. Use of a nasogastric tube for gastric and esophageal decompression in the dog and cat. Crowe DT Jr. JAVMA 188:1178-1182, 1986.
5. Capnographic documentation of nasoesophageal and nasogastric feeding tube placement in dogs. Johnson PA, Mann FA, Dodam J, et al. JVECC 12:227-233, 2002.

Suggested Reading

Nasoesophageal and nasogastric feeding tubes. Bosworth C, Bartges J, Snow P. Vet Med 99:590-594, 2004.