Animal Care & Nursing Subscriber guide

Assisted Feeding: Feeding Tubes and Refeeding

Animal Care and Nursing (D5 B, C; K31, K34) 13 min read, 2,909 words Last verified

How to choose, check and feed through nasal, esophagostomy and gastrostomy tubes, how to build up feeding safely and avoid refeeding syndrome, and how to care for a parenteral nutrition line.

Introduction

A sick animal that will not eat soon runs short of energy and protein. In cats, a few days without food can trigger hepatic lipidosis. Assisted feeding means giving nutrition by a route other than voluntary eating: a feeding tube (enteral nutrition) or an intravenous line (parenteral nutrition). The veterinarian picks the route and writes the feeding order. The veterinary technician usually does the rest: measuring and preparing tubes, checking tube position before every feed, calculating and giving each meal, flushing, caring for the stoma (the skin opening where a tube exits), watching for refeeding syndrome and teaching owners to feed at home.

Key facts

  • Use the gut whenever it works. Enteral nutrition supports gut motility, blood flow, local immunity and the mucosal barrier, even when only part of the energy need can be given this way.2
  • ISFM guidance for cats: start assisted nutrition no later than 3 days after the cat stopped eating, counting the days of poor appetite at home.2
  • Nasoesophageal (NE) and nasogastric (NG) tubes are for short-term feeding (about 3 to 5 days), need no anesthesia and take liquid diets only. Esophagostomy (E) and gastrostomy (G) tubes need general anesthesia and suit longer feeding.2
  • Check tube position before every feed. Radiography is the gold standard for confirming placement.26
  • A gastrostomy tube cannot be removed for at least 10 to 14 days, so a seal can form between stomach and body wall. An E-tube can be removed at any time.2
  • Feeding starts low and builds up: for example one-third of resting energy requirement (RER) on day 1 and two-thirds on day 2, reaching full RER within about 3 days. Patients at risk of refeeding syndrome start at no more than 20% of RER.2
  • Refeeding syndrome causes low potassium, phosphate and magnesium, weakness, hemolytic anemia and neurological signs.23
  • Total parenteral nutrition (TPN) must run through a central venous catheter because it is so hypertonic. The catheter is a dedicated line: no drugs, no blood draws.37

How the VTNE tests this

  • Perform and maintain prescribed treatments: measure, place and secure tubes, give tube feeds and care for stomas and lines (Domain 5 Task C; K34 "Animal nursing procedures and rehabilitation therapies").1
  • Choose the right tube for a described patient, and spot the tube that must not be used (Domain 5 Task C; K31 "Nutrition").1
  • Calculate RER and the volume of each feed from a diet's energy density.
  • Recognize a misplaced tube, refeeding syndrome, fluid overload or a stoma infection from monitoring findings (Domain 5 Task B).1

Core concepts

Why assisted feeding matters

When nutritional needs are not met, animals quickly go into negative energy balance. The results include gut dysfunction, organ dysfunction, hepatic lipidosis in cats, poor wound healing and death.3 Before a feeding plan starts, the patient should be rehydrated, have major electrolyte and acid-base problems corrected and be cardiovascularly stable.2

Why not just syringe feed or use appetite stimulants?

Syringe (forced) feeding can work for a short time, but it can cause food aversion, and most animals find it uncomfortable.3 Appetite stimulants give inconsistent intake. They are not recommended as the main way to feed a critically ill animal.3

Resting energy requirement

RER is the energy an animal needs at rest in a comfortable environment. It is the usual starting target for hospitalized patients on cage rest.2 The Merck Veterinary Manual gives two formulas: RER (kcal/day) = 70 x body weight (kg)0.75, or the linear version 30 x body weight (kg) + 70.4 The aim of nutritional support is to stabilize the patient, not to put back lost body condition, so early targets are conservative.2 Overfeeding a critically ill patient raises the risk of hyperglycemia, vomiting and diarrhea.2

The tube types

Tubes are named for where they enter and where the tip sits. An NE tube enters the nose and ends in the esophagus. An NG tube enters the nose and ends in the stomach. An E-tube enters through a small incision in the side of the neck and ends in the esophagus. A G-tube enters through the body wall into the stomach, placed surgically or with an endoscope (a percutaneous endoscopic gastrostomy, or PEG, tube). Jejunostomy (J) tubes end in the small intestine.23

Where each feeding tube enters and where its tip sits Head Esophagus Stomach NE tube (dashed): nose to distal esophagus NG tube: nose to stomach E-tube: side of neck to esophagus G-tube: body wall to stomach Tip
Figure 2. Feeding tube routes, simplified side view. Nasal tubes (NE, NG) enter the nose; an NE tip stops in the esophagus and an NG tip goes on into the stomach. An E-tube exits the side of the neck with its tip in the distal esophagus (in cats, 2 to 4 cm before the stomach). A G-tube passes through the body wall straight into the stomach. Dots mark tube tips.
Table 1. Feeding tubes compared
TubeTypical durationDietPlacementMain complications and cautions
Nasoesophageal (NE) or nasogastric (NG)Short term, about 3 to 5 daysLiquid diet only (small bore)Awake or lightly sedated, local anesthetic in the noseBlockage, dislodgement, sneezing and nasal discharge, tube in the airway. Avoid with nasal disease, facial trauma, esophageal disease, protracted vomiting, poor gag reflex, coagulopathy
Esophagostomy (E-tube)Short to long termLiquid diets and blended slurries; crushed medicationsGeneral anesthesiaStoma infection, dislodgement, blockage, kinking, head swelling with tight dressings. Can be removed any time
Gastrostomy (G-tube, PEG)Long termWide bore, more diet choicesGeneral anesthesia, surgery or endoscopyStoma infection, peritonitis. Cannot be removed for 10 to 14 days
Jejunostomy or nasojejunalVariableLiquid diet only (small bore)Surgery or specialized placementStoma infection, peritonitis. Not for home care

Source: ISFM 2022 consensus guidelines, Table 3, adapted.2

NE and NG tubes are often the first choice in critically ill patients because they are quick to place without anesthesia. An NG tube has one extra use: the stomach can be aspirated to measure residual volume, which helps in patients with ileus.2 If a cat still is not eating enough after about 5 days with a nasal tube, a longer-term tube such as an E-tube should be considered.2 Nasal tubes can also go home: in one study of 119 dogs and cats, NE tubes stayed in at home for a median of 6 days, and most complications were minor.5

Procedure or technique

Placing a nasal tube (technician assists or places, per hospital protocol)

  1. Gather the tube, a permanent marker, local anesthetic (for example lidocaine gel), lubricant, a syringe, sterile saline, suture or tissue glue, and an Elizabethan collar.52
  2. Hold the tube alongside the patient and mark the length. For an NG tube, measure from the nose to the last rib.6 An NE tube is marked shorter so its tip stays in the distal esophagus.
  3. Put local anesthetic in the nostril and wait for it to work. Sedate only if the veterinarian orders it.56
  4. Pass the lubricated tube into the ventral nasal meatus (the lower nasal passage) and advance it to the mark.6
  5. Check placement before securing. A lateral radiograph is the gold standard. One hospital protocol takes a first radiograph with the tube at the thoracic inlet, then a second at the last rib mark.6
  6. Secure the tube with sutures, staples or glue close to the nostril and along the face, away from the whiskers and the line of vision. Fit a soft collar.26
  7. Record tube type, size, length at the nostril, placement check and date.

Giving a tube feed

  1. Read the order: diet, volume per feed, number of feeds, flushes and drugs.
  2. Check the tube is still where it should be: the mark has not moved, the patient has not vomited the tube up, and the bedside check passes (see Figure 1). Owners in one study checked by aspirating with an empty syringe and then giving 2 mL of sterile saline while watching for a cough.5
  3. For gastric tubes, aspirate before each bolus feed (and every 6 hours during a constant rate infusion) to measure residual gastric volume.3
  4. Let the patient sit or lie comfortably with the head slightly raised. Avoid heavy restraint.2
  5. Give the feed slowly. Bolus feeds over 10 to 15 minutes are usually tolerated; Merck's hepatic lipidosis protocol gives E-tube feeds over 20 minutes.24
  6. Stop at once if the patient gags, coughs, retches, vocalizes or struggles, and check the tube for dislodgement.2
  7. Flush the tube with water or 0.9% saline after the feed and after any medication, then cap it.3
  8. Record the time, volume, kcal given, flush volume and any vomiting or regurgitation.

Daily care and monitoring

  • Check body weight, hydration and vital signs daily, and body condition weekly.2
  • Inspect E-tube and G-tube stomas for redness, swelling and discharge. Stoma infection and dislodgement are the most common E-tube complications.2
  • Watch for fluid overload: chemosis (swollen conjunctiva), gelatinous skin, clear nasal discharge, faster breathing and crackles. Feeds plus flushes can exceed daily fluid needs, especially in cats with heart disease.2
  • Label feeding tubes and IV lines clearly, especially when a patient has a central venous catheter as well.2
  • Keep offering food under supervision. Remove a tube only after voluntary intake has been 75 to 100% of RER for at least 3 to 5 days.2
Table 2. Bedside placement checks and what they mean
CheckExpected result if the tube is in the gutNotes
RadiographTube dorsal to the cricoid cartilage at the neck, tip in distal esophagus or stomachGold standard; used at placement
Aspirate with an empty syringeNegative pressure (the plunger pulls back)Negative pressure suggests the esophagus; air drawn back freely is a reason to recheck
Small volume of sterile salineNo coughA cough means stop and recheck
Capnography on the tubeNo CO2 waveformA CO2 waveform means the tube is in the airway

Sources: Ewel et al. 2026; Dumont et al. 2023.65 No bedside test was better than radiography in the studies Ewel et al. reviewed.

Refeeding syndrome

Refeeding syndrome is a dangerous metabolic reaction when a starved patient is fed more than it can handle. Insulin released by the meal drives glucose, and with it potassium, phosphate and magnesium, into cells. Blood levels fall. Signs include depression or coma, weakness, hemolytic anemia, glucose swings and severe electrolyte deficits. Thiamine (vitamin B1) deficiency can add neurological signs.2 At-risk patients include cats that have been missing, had no food at all, are very thin, or start with abnormal electrolytes.2

Prevention is a slow start: no more than 20% of RER on day 1 in at-risk cats, rising over 4 to 10 days.2 Merck's critical care chapter gives a similar rule for long-starved animals: start at 25 to 33% of daily needs and increase by 25 to 33% a day.3 If refeeding syndrome is suspected, stop feeding, tell the veterinarian and expect the plan to be adjusted.2

Feline hepatic lipidosis

Feline hepatic lipidosis (fatty liver) is the most common acquired liver disease of cats. It starts when an overweight cat stops eating and mobilizes more fat than the liver can process.4 Feeding is the treatment, but the order of steps matters:4

  • Rehydrate and correct electrolytes first. This often takes 1 to 2 days. Low potassium slows the stomach and raises the risk of vomiting and aspiration.
  • Correct potassium, start IV phosphate and give thiamine before feeding, to prevent refeeding syndrome. Phosphate is often measured every 3 to 8 hours during supplementation.
  • If the cat refuses oral food, start with an NE tube, then place an E-tube once the cat is a reasonable anesthetic risk. E-tube feeding is the preferred method.
  • Start at 25% of RER and increase over 3 to 5 days to full RER.
  • If vomiting recurs, recheck electrolytes and tube position.

A 2024 study of 48 cats with hepatic lipidosis found no survival difference between cats fed within 12 hours of admission and those fed later, which supports stabilizing first.8

Parenteral nutrition and line care

Parenteral nutrition is used when the gut cannot be used, for example with intractable vomiting, no gag reflex or high anesthetic risk.2 Partial parenteral nutrition (PPN), of amino acids and carbohydrate, can run through a peripheral vein and covers part of the energy need. TPN, which includes lipid, must go through a central venous catheter because its high osmolarity causes phlebitis and red cell lysis.3 TPN solutions are generally above 1000 mOsm/L.7

Line care is where the technician makes the difference:7

  • The catheter is a dedicated line: no drug injections, no blood sampling.
  • Place and handle it aseptically. Each bag holds 24 hours of nutrition and is changed every 24 hours; do not break the line between bag changes.
  • Check the catheter site, temperature, glucose, hydration and body weight on a schedule. Hyperglycemia is the most common metabolic complication.
  • A new fever raises concern for catheter sepsis; tell the veterinarian.
  • Wean TPN over 4 to 6 hours to avoid hypoglycemia. PPN can be stopped abruptly.

Flowchart

Is it safe to feed through this tube? Pre-feed check Feed due: read the order Tube mark at the same place? No vomiting since last check? Aspirate: negative pressure (gastric tube: residual OK)? Small saline test: no cough? Stoma or nose site clean, tube not kinked or blocked? Patient calm, no gagging, electrolytes checked as ordered? Feed slowly, head raised, then flush and record Stop if gagging or coughing YesYesYesYesYes NoNoNoNoNo DO NOT FEED Hold the feed Tell the veterinarian Expect a radiograph or tube replacement
Figure 1. Pre-feed safety check. Every question must be answered yes before anything goes down the tube. A moved mark, recent vomiting, free air on aspiration or a cough with saline can mean the tip has moved toward the airway, so the feed is held and the veterinarian decides whether to radiograph or replace the tube.

Species differences

  • Cats: at high risk of hepatic lipidosis when anorexic, so assisted feeding starts early (within 3 days of stopping eating).2 E-tubes are favored for long-term support in hepatic lipidosis, facial surgery, jaw fractures and pancreatitis.2 Maximum bolus volume once full RER is reached is 5 to 15 mL/kg per feed; constant rate infusion at 3 to 8 mL/h is usually tolerated.2 Kittens may need up to 200% of RER to grow.2
  • Dogs: the same tube types are used. NE and NG tubes had similar complication rates in dogs, so the choice often depends on whether gastric aspiration is wanted.2 Any long-starved animal, dog or cat, is at risk of refeeding syndrome.3
  • Rabbits: a rabbit that refuses food needs active feeding, by syringe, a small nasogastric tube (3 to 5 French) or a pharyngostomy tube. The least invasive method is often the most successful.9
  • Horses: nasogastric intubation in horses is a separate technique, covered in the equine nursing guide.

Calculation

Worked example. A 4 kg cat with an E-tube starts feeding today. The veterinarian orders one-third of RER on day 1, given in 4 equal feeds. The liquid diet provides 1 kcal/mL.

  1. RER = 70 x (body weight in kg)0.75 = 70 x 40.75 = 70 x 2.83 = 198 kcal/day.4
  2. Day 1 target = 198 kcal/day x 1/3 = 66 kcal/day.
  3. Volume per day = 66 kcal/day / 1 kcal/mL = 66 mL/day (kcal cancels, leaving mL).
  4. Volume per feed = 66 mL/day / 4 feeds/day = 16.5 mL per feed.

Check with the linear formula: 30 x 4 + 70 = 190 kcal/day, close to 198. On day 2 the target rises to two-thirds of RER (132 kcal, 33 mL per feed) if the cat tolerates day 1. If this cat had been missing for weeks, the day 1 target would be no more than 20% of RER, about 40 kcal.2

  • Never give anything down a tube whose position you have not checked. A feed into the airway can cause aspiration pneumonia. In the Ewel study, 9.8% of nasogastric tubes first went into the trachea.6
  • Label every feeding tube and IV line, especially a central venous catheter, so a feed can never go into a vein by mistake.2
  • Teach owners going home with a tube how to check placement, give the feed slowly, flush, clean the stoma and recognize trouble. Ask the owner to show you each step before discharge.
  • Tell owners to stop feeding and call if the pet coughs, gags, vomits the tube up, the tube moves or the stoma becomes red, swollen or smelly. In the home NE tube study, owners handled the tubes well and no airway displacement was found.5
  • After an E-tube is removed, clean the stoma and cover it with a dressing for 24 hours. It heals on its own.2

Common mistakes and exam traps

  • Feeding a hepatic lipidosis cat immediately on admission. Fluids and electrolytes come first, then a slow start at a fraction of RER.4
  • Thick food in an NE tube. Nasal tubes are small bore and take liquid diets only; slurries go through E-tubes and G-tubes.2
  • Pulling a G-tube early. Wait at least 10 to 14 days for the stoma to seal, or the stomach can leak and cause peritonitis.2
  • Using the TPN catheter for a blood draw. It is a dedicated line.7
  • Starting at full RER. Build up over several days; go slower still in starved patients.2
  • Thinking a nasal tube rules out eating. Keep offering food; some patients eat once the tube is out.2

Quick review

  1. Use the gut if it works; enteral beats parenteral.
  2. Cats: start assisted nutrition within 3 days of anorexia.
  3. NE and NG tubes: short term, no anesthesia, liquid diet only.
  4. E-tubes and G-tubes: general anesthesia, longer term, wider bore.
  5. NG tube length: nose to last rib.
  6. Check position before every feed; radiography is the gold standard.
  7. Stop the feed if the patient gags, coughs or retches.
  8. Flush with water or saline after every feed and medication.
  9. RER = 70 x kg0.75; start at about one-third and reach full RER in about 3 days.
  10. At refeeding risk: no more than 20% of RER on day 1; watch potassium, phosphate and magnesium.
  11. G-tubes stay in at least 10 to 14 days; E-tubes can come out any time.
  12. TPN needs a dedicated central line, aseptic handling and weaning over 4 to 6 hours.

Test yourself

5 questions written for this guide. Pick an answer, then check it.

Question 1A 5 kg cat has an esophagostomy tube. The veterinarian orders one-third of the resting energy requirement (RER) on day 1, using RER = 70 x (body weight in kg)^0.75, divided into 4 feeds. The diet provides 1 kcal/mL. About how much is each feed? (5^0.75 is about 3.34.)

Show answer

Answer: C. 19.5 mL

RER = 70 x 3.34 = 234 kcal/day. One-third is 78 kcal/day, which is 78 mL/day at 1 kcal/mL. Divided by 4 feeds, that is 19.5 mL per feed. A (58 mL) gives full RER in 4 feeds, ignoring the one-third start. B (78 mL) is the whole day's volume given as one feed. D (26 mL) divides the day 1 volume by 3 feeds instead of 4.

Source Feline Hepatic Lipidosis (Treatment), Merck Veterinary Manual

Question 2Before a scheduled bolus feed, a technician aspirates a cat's nasoesophageal tube with an empty syringe and air comes back freely. The tape mark at the nose has also moved. What should the technician do?

Show answer

Answer: A. Hold the feed and tell the veterinarian

A moved mark and free air on aspiration suggest the tube tip may have moved, possibly toward the airway. Nothing goes down the tube until the veterinarian confirms placement, usually with a radiograph. B and C put food or water into a tube of unknown position, risking aspiration pneumonia. D re-advances a tube blindly and still gives no proof of placement.

Source 2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat (Naso-oesophageal and nasogastric feeding tubes), J Feline Med Surg

Question 3A dog had a gastrostomy (G) tube placed 5 days ago. It is now eating well, and the owner asks if the tube can come out today. What is the best reply?

Show answer

Answer: D. No, a G-tube usually stays at least 10 to 14 days to let a seal form

A gastrostomy tube needs at least 10 to 14 days for a seal to form between the stomach and body wall; early removal risks leakage and peritonitis. Voluntary intake should also be adequate for 3 to 5 days first. A is true for an esophagostomy tube, not a G-tube. C adds a test that does not make early removal safe. B is wrong; G-tubes are removed once no longer needed.

Source 2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat (Gastrostomy tubes), J Feline Med Surg

Question 4A thin cat found after being missing for 4 weeks starts tube feeding. On day 2 it is weak, with low potassium and phosphate and a falling PCV. Which feeding plan most likely led to this problem?

Show answer

Answer: C. Starting at full RER on day 1

These are signs of refeeding syndrome: insulin released with feeding drives potassium, phosphate and magnesium into cells, and low phosphate can cause hemolysis. Starved, debilitated cats should start at no more than 20% of RER and increase over 4 to 10 days. A and B are the recommended prevention steps. D, the tube type, does not cause refeeding syndrome.

Source 2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat (Refeeding syndrome), J Feline Med Surg

Question 5A dog is receiving total parenteral nutrition (TPN) through a jugular catheter. A blood glucose check is due. What is the correct approach?

Show answer

Answer: A. Draw the sample from a peripheral vein, not the TPN line

A TPN catheter is a dedicated line: it is not used for drugs or blood sampling, and the line between bag changes should not be broken, because each break raises the risk of contamination and sepsis. B and C break the dedicated line. D stops TPN abruptly, which risks hypoglycemia; TPN is weaned over 4 to 6 hours.

Source Practical parenteral nutrition: when the gut doesn't work (Proceedings), dvm360

0 of 5 answered

Practise this topic

14 questions from the practice bank are linked to this guide. Answer them in practice mode with instant explanations.

Practise these 14 questions Practise the whole domain

Figure credits

  • Figure 1 Original diagram, VTNE Exam Prep
  • Figure 2 Original diagram, VTNE Exam Prep

References

  1. AAVSB. 2023 Veterinary Technician National Examination Content Outline. aavsb.org (accessed 2026-10-31) aavsb.org/wp-content/uploads/2025/04/AAVSB-2023-Veterinary-Technician-National-Examination-Content-Outline-2.pdf
  2. Taylor S, Chan DL, Villaverde C, et al. 2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat. J Feline Med Surg. 2022;24(7):614-640. PMC11107985 pmc.ncbi.nlm.nih.gov/articles/PMC11107985/
  3. Linklater A. Monitoring the Critically Ill Small Animal Using the Rule of 20 (Nutrition in the Critically Ill Animal). Merck Veterinary Manual. merckvetmanual.com (accessed 2026-10-31) merckvetmanual.com/emergency-medicine-and-critical-care/monitoring-the-critically-ill-small-animal/monitoring-the-critically-ill-small-animal-using-the-rule-of-20
  4. Merck Veterinary Manual. Feline Hepatic Lipidosis. merckvetmanual.com (accessed 2026-10-31) merckvetmanual.com/digestive-system/hepatic-diseases-of-small-animals/feline-hepatic-lipidosis
  5. Dumont R, Lemetayer J, Desquilbet L, et al. Tolerability of naso-esophageal feeding tubes in dogs and cats at home: retrospective review of 119 cases. J Vet Intern Med. 2023. PMC10658475 pmc.ncbi.nlm.nih.gov/articles/PMC10658475/
  6. Ewel RC, Levy NA, Beal MW. Retrospective evaluation of a standardized image-guided nasogastric tube placement protocol for preventing airway placement in dogs and cats. J Vet Emerg Crit Care (San Antonio). 2026. PMC12950928 pmc.ncbi.nlm.nih.gov/articles/PMC12950928/
  7. Freeman LM. Practical parenteral nutrition: when the gut doesn't work (Proceedings). dvm360.com, 2011 (accessed 2026-10-31) dvm360.com/view/practical-parenteral-nutrition-when-gut-doesnt-work-proceedings
  8. Wallace OP, Jablonski SA, Thomas JS, et al. Association of time to start of enteral nutrition and outcome in cats with hepatic lipidosis. J Vet Intern Med. 2024. PMC11586538 pmc.ncbi.nlm.nih.gov/articles/PMC11586538/
  9. Merck Veterinary Manual. Management of Rabbits. merckvetmanual.com (accessed 2026-10-31) merckvetmanual.com/exotic-and-laboratory-animals/rabbits/management-of-rabbits

Spotted an error? Email support@vtneexam.com and we will check it against the sources.