There are four types of "tube feeding" commonly used in critical care patients in veterinary medicine — orogastric, nasoesophageal, gastrostomy, and jejunostomy.
Orogastric feeding is used for the shortest period of time, generally only a day or two. This is also the most common method for feeding compromised neonates, who incidentally tend to tolerate multiple daily feedings better than adults. This method involves placing a tube at each feeding down the animal's esophagus to its stomach. Depending on the size of the animal and the size of the tube used either liquid diets (Clinicare, Vivonex) or a slurry made from a canned or dry food product may be used.
Nasoesophageal (NE) feeding involves placing a tube through the animal's nares, or nasal passage, into the esophagus. Another type of tube that is placed this way is a nasogastric (NG) tube, this tube also passes through the nares, continues down the esophagus and terminates in the stomach. The nasoesophageal tube is preferred because it does not irritate the esophageal sphincter, the round muscular opening, to the stomach, and therefore is not as likely to cause regurgitation. The NE tube is best for animals that are likely to begin eating on their own again in 3-7 days. The placement of the tube allows the animal to eat on its own if their appetite begins to return, allowing the veterinary staff to supplement the diet by feeding through the tube until the animal is able to eat enough calories to maintain his or her weight. These tubes are generally of a smaller diameter, and a liquid diet is administered through the tube.
Gastrostomy and jejunostomy tubes are both placed surgically while the animal is under general anesthesia. The gastrostomy tube terminates in the animal's stomach and the jejunostomy tube terminates in the jejunum, the first section of the animal's small intestine. These tubes will have an opening, called a port, that is secured with sutures on the animal's side where the diet is administered. These tubes are generally large enough in diameter that the veterinarian can choose between a liquid or slurry diet, however a jejunostomy tube generally requires an elemental or liquid diet of basic nutritional components since it bypasses the digestive action of the stomach.
Reference:
Michael S. Hand, Craig D. Thatcher, Rebecca L. Remillard and Philip Roudebush. Enteral-Assisted Feeding. Small Animal Clinical Nutrition 4th Edition. p371-373, 2000.
