- The management of ill or anorectic chelonians often requires oral medications and tube feeding in order to deliver effective treatment, maintain energy balance, boost nutritional status and replace fluid losses.
- It can be extremely difficult to administer oral medications to chelonians. The repeated use of rigid feeding tubes can result in damage to the oropharynx and esophagus, as well as being highly stressful for debilitated patients.
- Surgical placement of an esophagostomy tube is an effective tool in the treatment and rehabilitation of chelonians suffering from anorexia and chronic illness, allowing veterinary staff and owners alike the ability to administer oral medications and liquid diets with minimal intervention.
- Esophagostomy tubes can remain in place until the animal resumes feeding on its own accord or no longer needs oral medications.
Tortoises and turtles frequently present to the clinician in an anorexic state. Anorexia may be associated with acute or chronic illness. It is essential for recovery to identify the underlying cause of anorexia and to counteract catabolic processes. Fluid therapy and nutritional support are the mainstays of therapy in many cases. Along with supplemental feeding, a variety of oral medications may be required, however, this can be difficult to achieve because chelonians are reluctant to allow handling of their heads or opening of their mouths (Fig 1). Repeated interventions of assist feeding and medicating are also stressful and can also traumatize the esophageal lining.
The use of esophagostomy tubes (E-tubes) allows administration of oral medications and crucial nutritional support while minimizing stress and the risk of esophageal trauma associated with repeated rigid gavage tube feeding. Esophagostomy tubes are very well tolerated and the patient can even eat normally with the tube in place. Patients can be discharged to be medicated and fed at home until they have overcome illness and begun eating of their own accord. Once the patient has fully recovered, the E-tube is easily removed in the clinic and the surgical site heals well by secondary intention in most cases.
E-tube placement is recommended for any chelonian patient that requires repeated oral treatments, such as nutritional support or oral medications, for greater than 2 weeks or for those in which it is difficult to administer oral treatments due to temperament or physical strength. In most cases where nutritional support or oral medications are required, an E-tube should be considered, and in some cases for even shorter periods.
Surgical risks of E-tube placement include iatrogenic damage to structures in the neck, most notably the jugular vein and carotid artery. Infection at the surgical site is uncommon when appropriate monitoring and cleaning of the site is performed. Aquatic chelonian species may need to be ‘dry-docked’ whilst undergoing treatment as the likelihood of infection may be higher if the surgical site is in constant contact with water. Anesthetic risk should be considered and appropriate protocols utilized on a case-by-case basis. Finally if the tube is improperly secured, it is possible that the tube could be pulled out.
Most of the equipment required for esophagostomy tube placement is commonly present in most veterinary clinics (Fig 2):
- Surgical scrub (povidone-iodine)
- Soft feeding tube or catheter of appropriate diameter to maintain patient comfort and allow easy passage of desired feeding formula*
- Three-way stopcock or tap (optional)
- Non-toxic, permanent marker
- Adhesive bandage material (e.g. Elastoplast or similar) to make a butterfly tape for attachment of tube to skin and affix the tube to the shell
- Rat-tooth tissue forceps, e.g. Brown Adson
- Needle holders
- Curved hemostats of appropriate length for patient size, typically 4-6 in (10-15 cm)
- Scalpel blade (size 11 or 15)
- Non-absorbable suture on a cutting needle
* A variety of tubes can be used for esophagostomy tube placement ranging from nasogastric feeding tubes to red rubber catheters or non-medical plastic tubing. Tube diameter should be 30% to 50% of esophageal diameter, so as not to clog easily with formula if too narrow, and not to occupy too much of the esophageal lumen such that it prevents voluntary feeding. The volume of the tube should also be predetermined so that the exact volume used to flush the contents of the tube is known.
Select an anesthetic and analgesic plan that allows good restraint and prevents excessive movement. Manual restraint and local anesthesia is often sufficient to allow E-tube placement in very weak patients that would be considered a high anesthetic risk. Some patients may require sedation or general anesthesia. Specific anesthetic protocols are beyond the scope of this article but should be carefully considered on a case-by-case basis (Eatwell, 2010, Wright 2008, Mader 2006).
First, pre-measure the catheter from the cranial rim of the plastron to the junction of the pectoral and abdominal scutes and mark it with a permanent marker (Fig 3).
Although the esophagostomy can be performed on the left or right lateral neck, it may be safer and easier to make the incision on the left side of the neck. The right jugular vein tends to be larger than the left jugular in chelonians (Mader 2006). It may also be easier to redirect the cathether into the esophagus from the left hand side after pulling the tube through the incision, as the esophagus travels down the right side of the neck.
Hold the chelonian in lateral recumbency with the head extended manually. Aseptically prepare the surgical site with 1% dilute povidone iodine. Open the mouth and pass the closed, curved hemostats into the esophagus. Push laterally, tenting the skin on the middle of the caudolateral neck (Fig 4). Whenever possible, visualize and avoid the jugular vein which lies in the dorsolateral neck and the carotid artery which lies ventrolaterally (Fig 5).
Once the tip of the hemostats is visible below the skin, make a small horizontal incision over the tip of the closed hemostats, just small enough to allow the end of the instrument to protrude through the esophageal wall and skin (Fig 6).
Open the hemostats and place the end of the feeding tube into the jaws of the hemostat in a parallel fashion to the hemostat. Secure the hemostats (Fig 7). Then pull the end of the tube through the incision and out through the open mouth (Fig 8).
Reversing the grip on the end of the feeding catheter, guide the tube back into the esophagus. Carefully direct the tube towards the stomach until the mark on the tube is level with the skin incision (Fig 9, Fig 10).
Suture the tube in place using the butterfly tape to the superficial skin of the neck. A finger-trap suture either by itself or incorporated into the tape butterfly is the most secure technique (Fig 11).
Once the tube has been secured, attach the tube to the carapace using tape, expoxy, dental acrylic, or other removable adhesives. It is important to curve the tube over the head onto the contralateral side of the carapace, preventing the creation of a loop that would allow the animal to pull the tube out with the forelimb (Fig 12).
If the tube is very long it can be cut and a three-way stopcock or tap used to seal the end. Otherwise curl the capped feeding tube around the carapace securing it with tape (Fig 13). Whichever method is used, it is vital the tube remains sealed at all times except when in use.
Once in place, radiographs can be performed to determine location of the end of the tube in the stomach. It is important to flush the tube with warm water at this stage and close the end.
Volume and frequency of feeding
When beginning to feed an anorectic chelonian, it is important that fluid and electrolyte balance is restored, which initially may necessitate the use of intravenous or subcutaneous fluids. In addition to provision of nutrients, the E-tube can also be used to provide fluids and electrolytes. A basic rule for calculating the volume to be fed in chelonians is 1% to 2% of bodyweight every 24 hours. Stahl (2006) suggests the estimated stomach volume in reptiles to be 2% of bodyweight or 20 ml/kg, however, great care must be taken not to feed these patients too much too soon as this in itself can lead to problems. As in all veterinary patients, regular feedings should be based on calculated energy requirements.
Overfeeding chronically anorexic patients can lead to life threatening hypokalemia and hypophosphatemia. When high calorie foods are fed following periods of starvation, marked rises in insulin levels drive glucose and electrolytes into cells resulting in such imbalances, suggesting that reptiles may be susceptible to changes comparable to refeeding syndrome seen in human anorexic patients (da Silva et al 1990). Reptile patients that have been chronically anorexic should therefore be fed no more than 50% of their caloric requirements until they are well hydrated, electrolyte imbalances have been corrected, and they appear outwardly more bright, alert and active (Mader 2006) . Incremental increases of 10% to 50% volume fed can be made gradually over several days once the patient is showing signs of recovery. It is recommended to monitor serum glucose and electrolytes during this time as plasma levels classically fall precipitously. Most good quality clinical recovery formula and diets provide detailed information on how to prepare diets and calculate energy requirements according to the calorie density of the product in question. Starting with small volumes of 5-7 ml/kg of diluted feeding formula and gradually increasing as the animal recuperates is recommended (Stahl 2006).
When using the tube, slow administration of feeding formula is advised. Oral medications should be syringed first followed by the larger volume of feeding formula. Afterwards, a suitable volume of warm water must be used to flush the contents of the entire tube to prevent blockages before sealing again. This ensures long-term patency of the tube, which can be kept in place for several months if necessary with minimal risk of complications.
If a blockage is encountered during feeding aspirate slowly before trying to apply positive pressure on the feeding syringe again. Flushing and aspirating with warm water usually is effective if feeding formula has caused a blockage.
It is vital to regularly monitor the surgical site for signs of inflammation or infection. The site should be cleaned daily with dilute povidone-iodine for the duration of tube placement.
Monitoring weight gain and fecal output is also very important for the duration of use.
The tube can be removed once the animal regains its appetite and demonstrates self-feeding for at least 1-2 weeks. Normally no primary closure is needed and the wound heals by secondary intention over several days.
The use of esophagostomy tubes in ill or chronically anorectic chelonians is an extremely valuable tool for the clinician in terms of improving welfare and prognosis for recovery. It is a relatively simple yet highly effective procedure, which can drastically improve the chances of recovery as well as allowing home care to be provided by the owner.