KEY NOTES

It is important to be able to identify and use feeding tubes in order to provide enteral nutritional support. "Enteral" means within the gastro-intestinal tract, and "enteral diets" are those taken by mouth or via a feeding tube.

Enteral nutritional support may be indicated in a number of cases:

• Anorexic animals.
• Dysphagic animals.
• Patients suffering physical inability to eat; for example due to injuries or trauma to the oral cavity.
• Comatose patients.
• Orphaned neonates.
• Hypermetabolic patients (Hypermetabolism may occur if an animal has had prolonged fluid therapy; more energy is consumed than that provided by the fluids and body proteins may be utilised as an energy source = autocannibalism).

1. OROGASTRIC (STOMACH TUBE)
   • As its name implies, this tube is passed to the stomach, through the oesophagus via the oral cavity.
   • It is suitable for short-term use only since there is a danger of the animal biting through the tube and swallowing the lower portion.
   • Available in a variety of sizes; 10Fg is suitable for a medium sized dog.
   • Made of flexible PVC.
   • An 8Fg dog catheter cut to the desired length is ideal for stomach tubing a tortoise.
   • Disadvantages of orogastric tubes include stress, inflammatory damage and possible gastric reflux.
2. NASOGASTRIC & NASOESOPHAGEAL TUBES
   
   • The nasogastric tube is passed from the nostril to the stomach.
   • The nasoesophageal tube is similar but terminates in the thoracic oesophagus minimising the risk of reflux oesophagitis.
   • These are suitable for short-term to medium-term use and may be indwelling.
   • A variety of sizes are available; 5-16Fg (5Fg being suitable for cats).
   • Made of PVC or silicone elastomer.
   • To test for correct placement flush with 5mls saline; the patient will cough if the tube is in the trachea; if the fluid is drawn back and tested with Litmus paper - gastric fluid will read red (acidic) and lung fluid will be neutral.
   • An Elizabethan collar must be used to prevent patient interference if the tube is indwelling.
   • Complications associated with use include epistaxis and rhinitis.
3. PHARYNGOSTOMY TUBE
   
   • The pharyngostomy tube is passed from the pharynx to the distal portion of the oesophagus.
   • It is suitable for medium to long-term use.
   • Sizes available range from 10-24Fg; 10-18Fg are suitable for small animal use.
   • Latex Foley catheters are often utilised for this purpose because they are soft.
   • The pharyngostomy tube has largely been superceded by the PEG tube due to reported complications such as stoma formation, aspiration of food, reflux oesophagitis and tube displacement.
   • General anaesthesia is required, and there is the risk of peritonitis.
4. PEG TUBE (PERCUTANEOUS ENDOSCOPE GUIDED (OR SURGICALLY PLACED) GASTROSTOMY TUBE
   
   • The PEG tube is placed directly into the stomach via a surgical incision.
   • A PEG tube may also be placed into the duodenum or jejunum.
   • It is suitable for long-term use as it is well tolerated by the patient and possesses none of the complications associated with tubes that take the oesophageal route.
   • Sizes range from 16-24Fg.
   • General anaesthesia is required for placement and the procedure does carry the risk of peritonitis.
   
   N.B. Under normal circumstances, an animal will stop feeding when it is full. This is obviously not the case when feeding tubes are employed. The maximum stomach capacity of an adult dog is 90mls of feed/kg. The maximum stomach capacity of an adult cat is 45mls of feed/kg. Always make sure that the daily nutritional requirements are divided into 4-6 meals to avoid the risk of over-stretching the stomach.
   
   Orogastric, nasogastric and pharyngostomy tubes should be measured to the 9th rib in cats, and the 7th intercostal space in dogs.