- Estimated crop volume is 50 ml/kg. Begin feeding one-third to one-half of estimated crop volume to the critically ill patient.
- Always tube feed warm formula (100-105°F or 38 to 41°C).
- Tube feeding should always be the last treatment performed.
- Most birds are tube fed between two to four times daily.
Tube feeding, also known as gavage feeding, is an essential part of avian supportive care. Sick birds are often presented with a history of anorexia, and glycogen stores may be depleted within hours in the granivore (including psitacine, passerine and galliform species) secondary to a relatively high metabolic rate. Another important indication for gavage feeding is a documented drop in body weight of 5% to 10%.
- Curved stainless steel ball tipped feeding needles or gavage tubes are easiest to use in psittacine birds (Ejay International, Glendora, CA) (Table 1).
Table 1. Suggested feeding needle or gavage tube size in select psittacine birds Species Feeding needle size (gauge) Finch 16-18 Canary 16-18 Budgerigar parakeet 14-16 Lovebird 12-14 Cockatiel, small conure 12-14 Large conure 10-12 Amazon parrot, small cockatoo 8-10 Large cockatoo, macaw 8-10
- Flexible rubber tubing such as red rubber catheters or silicone tubes (Sovereign Feeding Tube, Sherwood Medical, St. Louis, MO) may also be used in parrots when an oral speculum is in place (Jorgensen Laboratories, Loveland, CO) (Fig 1).
Contraindications and potential complications
The most important contraindication for tube feeding is lack of experience since improper tube feeding can result in:
- Aspiration and possible death
- If the tube is passed forcefully, it may lacerate the oropharynx. If continued, food can be injected through the laceration and into the surrounding tissue potentially causing life-threatening cellulitis.
Restraint and tube passage should be practiced so the technique may be performed efficiently, safely, and gently in the clinical patient. Tube feeding is also contraindicated in birds that are regurgitating, dehydrated, or those that are not alert, responsive, or able to keep their heads elevated.
Calculate the volume to be fed
The crop may hold up to 5% of body weight, or 50 ml/kg, in the adult bird, although neonatal crops can hold more proportionally. It is prudent to begin with a food volume that is one-third to one-half of estimated crop volume, especially in the critically ill patient. As long as regurgitation does not occur, increase the volume fed over two to three feedings.
For example, the crop of a debilitated 100-gram bird should hold approximately 5 ml of fluid. For the first feeding, tube feed 2 to 3 ml of food. As long as this volume is tolerated, increase the next tube feeding to 3 or 4 ml. By the third feeding, volume may be increased to 5 ml.
Step-by-step instructions for tube feeding
- The bird should be warm and hydrated prior to tube feeding.
- It is crucial that hand-feeding formula be warm (100-105°F or 38 to 41°C) since formula that is too cold may promote regurgitation.
- Feeding should always be the last treatment performed to minimize the risk of regurgitation secondary to the stress of restraint.
- Restrain the patient near its hospital cage so it may be returned promptly. Always restrain the patient upright for tube feeding.
- Until one is proficient, tube feeding should be performed as a two-person procedure. One person should restrain the patient and monitor its status while the second person passes the tube. With practice, it is possible for one person to gavage feed using a ball-end metal feeding tube. Gently yet firmly stretch the neck thereby straightening out the normal S-shaped curve of the avian neck and therefore straightening out the esophagus (Fig 2).
- Palpate the thoracic inlet region before passing the tube to ensure the crop is free of food or fluid. Delayed crop emptying is a common finding in the ill avian patient.
- Pass the tube starting from the bird’s left. Direct the tube towards the right and down into the crop at the level of the thoracic inlet (Fig 3). You will see feathers on the right side of the neck move as the tube descends into the crop. If using a metal gavage tube, avoid the fleshy commissure of the mouth or rictus, which can easily bruise. Pass the tube firmly yet gently, slowly, and carefully. Never force the tube.
- The large, muscular tongue of the psittacine prevents easy visualization of the back of the throat; therefore correct positioning of the tube must be confirmed by gentle palpation of the neck. (Ball tipped tubes are also easily seen through the thin skin of the neck in small birds).
- Infuse food into the crop using a steady, measured pace while carefully watching for formula welling up in the back of the throat.(If food does well up in the back of the throat, withdraw on the syringe plunger to reduce the volume of food infused. Next, remove the tube and return the bird to its enclosure. The bird may shake its head and expel any excess food).
- Return the bird to its cage.
- Rinse and clean syringes and tubes immediately after use.
Depending on the product used and the clinical condition and caloric needs of the patient, tube feeding is often performed two to four times daily. Small birds eat a higher percentage of their body weight on a daily basis than large birds. For instance, a 100-gram bird may eat up to 25% of its body weight daily while a 1000-gram bird may eat approximately 10% of its body weight per day. Therefore more frequent feedings are often indicated in small birds and juveniles.
Table 1. Suggested frequency of feeding based on species.
|Species||Frequency of Feedings|
|Budgie, lovebird, cockatiel, small conure||q6 hours|
|Large cockatoo, macaw||q8-12 hours|
Carefully monitor stool production, and continue to provide the tube fed patient with fresh food and water. Identify foods commonly eaten by the patient at home and offer these items in the hospital.
Weigh the patient on a gram scale at least once or twice daily to ensure that it is at least maintaining, and preferably gaining weight. Weigh the patient at the same time or times each day as weight can normally fluctuate throughout the day.
Calculation of caloric requirements
For short-term enteral nutritional support, tube feeding is often more a function of the volume that may be safely administered. When patients must be gavage fed for an extended period of time, it is prudent to calculate maintenance or resting energy requirements (MER). See Calculating energy requirements for additional information.
|Product||Emeraid Intensive Care Omnivore*||Emeraid Intensive Care Herbivore*||Emeraid Intensive Care Carnivore*||Emeraid Intensive Care Piscivore|
|Indications||Semi-elemental diet (readily absorbable, easily digestible) for the critically ill granivore||Semi-elemental diet (readily absorbable, easily digestible) for the critically ill herbivore||Semi-elemental diet (readily absorbable, easily digestible) for the critically ill carnivore||Semi-elemental diet (readily absorbable, easily digestible) for the critically ill fish-eater|
|Protein||Provided as balanced amino acids||Low||High; provided as balanced amino acids||High|
|Fat||9.5%||9.50%||34.00%||4.40% + fish oil added|
|*Emeraid Intensive Care Omnivore and Emeraid Intensive Care Herbivore should not be provided as the sole source of nutrition for more than 7 days. Both Emeraid Intensive Care Carnivore and Emeraid Sustain Herbivore can be fed for an extended time.