Nutritional support has long been regarded as a key part of managing hospitalised people with many different diseases. This is supported by scientific research highlighting reduced complications, shorter hospitalisation times and reduced morbidity and mortality when enteral or parenteral nutrition support is provided. There is now similar evidence in veterinary medicine highlighting improved outcomes in hospitalised patients who consumed calories (Brunetto et al., 2010).
Reasons to place feeding tubes
Alternative approaches to feeding tubes include the provision of supportive care and the use of appetite stimulants. Supportive care, including the correction of fluid, electrolyte and acid-base disturbances and medications such as anti-emetics and analgesics, can improve the appetite of a small subset of hospitalised patients. However, supportive care is unlikely to restore the appetite of patients with moderate to severe anorexia.
Alternative approaches to feeding tubes include the provision of supportive care and the use of appetite stimulants
The use of appetite stimulants, such as mirtazapine, is now commonplace in general practice, and these medications do have a role in managing conditions such as chronic kidney disease. However, appetite stimulants are not effective with more advanced anorexia. In addition to this, mirtazapine can be associated with adverse effects and is not thought to be effective in dogs.
The benefits of feeding tubes stretch beyond the needs of the patient and include the needs of the pet owner and veterinary staff. Many dogs and cats are referred for feeding tube placement, but referral may not be logistically possible or financially feasible for many owners. The placement of feeding tubes in general practice thus allows for continued care at the primary practice, thereby increasing the bond between the practice and the owner. Furthermore, nursing and support staff tasked with feeding dogs and cats via feeding tubes often enjoy the care they provide, which ultimately leads to improved job satisfaction.
Indications for placing feeding tubes
Feeding tubes are usually placed to manage common conditions that cause prolonged anorexia in cats and dogs. Typical indications in cats include liver disease (eg cholangiohepatitis), pancreatitis, trauma (eg dog attacks, vehicular accidents) and toxicities (eg acute kidney injury). In dogs, feeding tubes are most often placed to manage pancreatitis and gastrointestinal disease (eg inflammatory bowel disease, parvoviral enteritis). Feeding tubes should also be strongly considered in patients undergoing major surgery after which a prolonged recovery is expected (eg septic peritonitis).
Equipment needed to place feeding tubes
Most feeding tubes do not require specialised equipment or advanced training. For example, naso-oesophageal (N-O) and oesophagostomy (O) tubes are placed using basic equipment found in most general practices. Although percutaneous endoscopic gastrostomy (PEG) tubes require flexible endoscopy and advanced training, surgical gastrostomy tubes can often be placed with relative ease at the time of abdominal surgery.
Diets to use with feeding tubes
Feeding tubes require the administration of liquid diets; this can be in the form of specialised liquid diets or liquidised canned diets. Commercial liquid diets are currently available in various formulations, including those for renal disease (dog and cat), convalescence (dog and cat) and fat restriction (dog only). Several canned diets can also be used with feeding tubes by adding water and liquidising them in a blender. This approach opens up many more diet options to manage different conditions (eg hydrolysed diets). Liquidised diets can be more economical compared to liquid diets, but this approach is more time-consuming.
Feeding tubes require the administration of liquid diets; this can be in the form of specialised liquid diets or liquidised canned diets
Types of feeding tubes
Naso-oesophageal tubes
N-O feeding tubes are ideal for short-term nutritional support for three to seven days. These do not require general anaesthesia or surgery to place, making them ideal for patients who are not stable enough for anaesthesia (eg anaemic) or not candidates for surgery (eg coagulopathic). Because N-O tubes are very narrow in diameter, they only tolerate pure liquid diets and not liquidised canned diets.
N-O tubes should not be used in cats and dogs with nasal disease.
Placement is usually achieved with light sedation and topical anaesthesia. Correct placement should be verified with radiography or another technique (eg capnography).
Oesophagostomy tubes
O tubes are the most versatile feeding tubes in cats and dogs and can be used for short- to medium-term nutritional support (eg one to four weeks). For these reasons, they are ideal for conditions such as pancreatitis and gastrointestinal disease. However, placing O tubes in large to giant breeds can be technically demanding, so these patients may benefit from an alternative type of feeding tube. In most other animals, relatively large-bore tubes can be placed, which enables the use of both liquid and liquidised canned diets.
Placing O tubes in large to giant breeds can be technically demanding, so these patients may benefit from an alternative type of feeding tube
The main contraindications for O tubes are severe oesophageal diseases, including megaoesophagus and oesophagitis, and any contraindication for anaesthesia or surgery.
The placement of O tubes requires general anaesthesia; however, the equipment needed is minimal (ie curved haemostat, scalpel, suture, gloves and tube). Correct placement of the tube should be confirmed with radiography, with the distal end of the tube in the caudal oesophagus.
Gastrostomy tubes
Because gastrostomy (G) tubes bypass the oesophagus, these are ideal for use when oesophageal disease is present. They are also useful in large to giant breeds. G tubes are usually relatively large-bore tubes, which enables the use of liquidised diets. These tubes can be used for medium- to long-term nutritional support.
The main contraindications for G tubes are conditions that may compromise the formation of a stable stoma between the gastric and abdominal walls. This can include gastric pathology (eg neoplasia), ascites, hypoproteinaemia and high-dose corticosteroid therapy.
G tubes can be placed with endoscopy (PEG tubes) or at surgery. The latter is generally performed at the end of another procedure (eg mass resection, foreign body removal).
Complications associated with feeding tubes
The complications associated with feeding tubes may be seen as a barrier to their placement in general practice. However, the reported complications are usually minor:
- With N-O tubes, nasal irritation (eg sneezing, discharge) and inadvertent removal are the most commonly reported complications
- Two recent large studies into the complications associated with O feeding tubes reported stoma infections and tube dislodgement as the most common complications (Breheny et al., 2019; Nathanson et al., 2019)
- Complications associated with G tubes are a lot more serious and include septic peritonitis due to tube dislodgement or premature removal
- Feeding related complications, including vomiting, regurgitation and diarrhoea, may be seen with all types of tubes. However, these can usually be managed by altering the diet type and/or feeding plan
The complications associated with feeding tubes may be seen as a barrier to their placement in general practice. However, the reported complications are usually mino
Use of feeding tubes at home and the removal of tubes
O and G tubes are often used at home until the patient has fully recovered from illness. Although historically N-O tubes are not used at home, a recent publication highlighted that this tube type can be effectively used at home (Dumont et al., 2023).
The removal of N-O and O tubes does not require sedation or general anaesthesia, but the removal of G tubes may. The stomas associated with O and G tubes are left to heal by second intention (ie sutures are not needed).
Summary
Feeding tubes can be safely placed and effectively used in general practice to manage anorexia and malnutrition associated with several diseases in dogs and cats. The provision of enteral feeding can not only improve patient outcome but also help pet owners and veterinary staff.
