Local anesthesia is applied in the ventral meatus of the nasal cavity. The extremity of a nasoesophageal tube is usually sitting in the middle of the thoracic esophagus. The length of the tube is measured from the tip of the nose to the level of the 8th or 9th rib. If a nasogastric tube is placed, it is measured from the tip of the nose to the last rib. The tube is introduced in the ventral meatus of the nasal cavity after the nares are gently pushed dorsally with the thumb while the hand is holding the head of the dog or cat. The tube is advanced and when it reaches the nasopharynx the dog or cat will start swallowing, which will facilitate the passage of the tube in the esophagus. The tube is then advanced to the desired length to reach the middle of the thoracic esophagus or the stomach (Figure 4.2).
If the patient is coughing, the tube should be withdrawn because it is progressing into the larynx and the trachea.
After placement of the tube it is stabilized on the side of the nares with a simple interrupted suture. Another suture is placed on the side of the lips and cheeks to stabilize the tube.
It is paramount that appropriate placement of the tube is confirmed before it is used to provide nutrition to the patient. Since the tubes are small it may not be possible to palpate the tube in the neck. First aspiration of the tube should generate negative pressure if it is in the esophagus or gastric content if it is in the lumen of the stomach. If air is aspirated it has been placed in the airway. If the tube is in the stomach, injection of 5 ml of air should induce borborygm, easily detected with a stethoscope placed over the stomach. Injection of 5 ml of sterile saline will induce coughing reflex if the tube is in the airway. Finally, since the feeding tubes are radiodense a lateral radiograph should confirm the accurate placement of the tube (Figure 4.2).
4.1.4 Utilization
Nasoesophageal and nasogastric feeding tubes can be used immediately to support the patient. Only liquid diet can be used. After calculating the daily calorie requirement of the patient the diet is delivered in six feedings very slowly. The tube is then flushed with saline to prevent obstruction.
The nasogastric tube can also be used to keep the stomach decompressed in case of severe ileus after abdominal surgery.
4.1.5 Tips
The administration of a long‐acting local anesthesia in the nasal cavity every four to six hours greatly improves the tolerance of the tube by the patient.
4.1.6 Complications
Nasoesophageal and nasogastric tubes can be dislodged if the patient is vomiting. Epistaxis and sneezing can occur with a nasoesophageal or nasogastric tube. Local anesthesia reduces the risk of sneezing. Nasogastric tubes may trigger gastroesophageal reflux and regurgitation. In this case it is then recommended to convert the tube into a nasoesophageal tube by pulling the tube into the esophagus. Obstruction of the tube can occur. It is important to regularly flush the tube with saline.
4.2 Esophagostomy Tube
4.2.1 Indications
Esophagostomy tubes are used to provide long‐term support to the patients. Esophagostomy tube can be maintained for several weeks to months. They are mostly used to support anorexic patients with chronic systemic disease. They are also used for patients with severe trauma to the head, after surgery of the oral cavity, or to keep the stomach decompressed (Crowe and Devey 1997a; Devitt and Seim 1997; Levine et al. 1997; Kanemoto et al. 2017).
Esophagostomy tubes are contraindicated for dogs or cats with esophageal disease. Megaesophagus, esophagitis, esophageal stricture, and reflux are contradictions for the placement of an esophagostomy tube. However, an esophagostomy tube has been used to keep a megaesophagus decompressed to reduce the risk of aspiration pneumonia in one dog (Kanemoto et al. 2017). Esophagostomy tubes have also been advanced to the jejunum to support dogs with pancreatitis or anorexia (Cummings and Daley 2014).
The main advantage of an esophagostomy tube is that a diet modified into a gruel can be used to support the patient. The nutrition is delivered three or four times a day. Diet is blenderized with enough water and delivered slowly and warm to the patient. Also, dogs and cats can eat orally even if the tube is in place. The tube is then used for complement if the caloric intake is not sufficient.
4.2.2 Materials and Equipment
Esophagostomy tubes are usually 16–20 Fr in diameter. A red rubber tube, a polyvinyl chloride tube, a polyurethane tube, or a silicone tube can be used for an esophagostomy tube (Figure 4.3). The holes at the extremity of the tube need to enlarged to prevent clogging of the tube with the gruel (Crowe and Devey 1997b; Devitt and Seim 1997).
The dog or the cat needs to be placed under general anesthesia and intubated for the placement of an esophagostomy tube. The patient is positioned in right lateral recumbency and the left side of the neck is clipped and surgically prepared and draped.
4.2.3 Surgical Techniques
The length of the tube is measured from the proximal part of the esophagus to the level of the 8th or 9th rib. The appropriate length is marked on the tube.
A long curved forceps is introduced through the oral cavity in the proximal esophagus (Figure 4.4a). The tip of the forceps is palpated percutaneously in the proximal part of the neck.
A small skin incision is made over the tip of the forceps (Figure 4.4b). It is important to tent the soft tissue of the neck while the instrument is tipped up in the neck. This minimizes the risk of stabbing the jugular vein or the carotid artery. The tip of the forceps is then exposed after incising the wall of the esophagus. The incision should be long enough to advance the tip of the forceps through the wall of the esophagus. A large incision will result in leakage of saliva around the tube in the subcutaneous area, inducing cellulitis.
The tip of the esophagostomy tube is then grabbed and pulled in the oral cavity (Figure 4.4b and c). The tube is then reinserted in the esophagus (Figure 4.4d). It is important not to wrap the esophagostomy tube around the endotracheal tube. The tube is advanced until it passes the point of insertion in the esophagus. Then it can be pushed in the esophagus to the desired length.
As an alternative technique a special trocar can be used to place the esophagostomy tube. The tube is first introduced in the esophagus through the mouth (Figure