Common avian surgical procedures for general practitioners (Proceedings)

Treating dermal injuries, fracture stabilization, stabilization of fracture sites after internal orthopedic repair, joint injuries and prevention of self trauma are common reasons bandages are used on avian patients.  Bandages function to apply pressure to reduce dead space, swelling edema and hemorrhage; protect the wound from pathologic microorganisms; immobilize the wound and underlying fractures; protect the wound from desiccation and additional trauma from abrasions or self-mutilation; absorb exudates and help debride the wound surface; and provide comfort for the patient.1 Although bandages may be less stressful to apply than internal fixation of a fracture it is imperative that the proper application technique be used to prevent increased trauma to the affected area.  Bandages that are applied incorrectly may not help the condition of the patient, if applied too tight, this will restrict blood flow to the distal extremity, if immobilization of the joints above and below the fracture is not achieved, the possibility of a nonunion significantly increases.  Often what first appears to be a simple technique to apply is not that simple but requires skill, the proper materials, patience, a properly restrained patient and an understanding of the forces to be controlled by the bandage. 

Common bandage materials used on avian patients include Vet-Wrap (3M Animal Care Products, St. Paul, MN), adaptic (Johnson & Johnson, New Brunswick, NJ), 4 X 4 and 2 X 2 gauze sponges, white cloth tape, cast padding, Hexcelite (Hexcel Medical Co., Dublin, CA), syringe cases, aluminum rods and roll gauze.  One of the most important aspects of bandaging avian patients is that most of the bandage materials listed above do not come in sizes applicable to patients that weigh less than 300 grams, especially passerines that weigh less than 30 grams.  Modification and manipulation of the smallest size of the bandage material mentioned above will be sufficient for proper application on the small avian patients.  Vendors do not manufacture and sell specific splints for the different avian species or for animals the size of most pet birds.  Therefore veterinarians are required to use their skills at manufacturing splints out of Hexcelite, syringe cases, aluminum rods or some other ridged material.  To fabricate a syringe case splint, a dremel tool is required to cut and shape the splint to the size of the patient's anatomy that needs to be immobilized.  Hexalite, a thermal sensitive material that becomes malleable when placed in hot water then hardens at room temperature in the shape of the injured anatomical area.  Ultraviolet (UV) dental acrylic can be used in a similar manner as Hexalite, but cures hard when exposed to the UV light generated by a UV gun.  Eye protection must be worn by veterinarians and hospital staff when using UV dental acrylic curing instrument.

The owner of bandaged avian patients must understand the importance of monitoring the bandage and affected area and to make sure they make the required follow up visits for reevaluation.  Veterinarians, veterinary technical staff and owners should monitor the bandage site for slippage of the bandage/splint, swelling distal to the bandage, non-use of the limb or a regression of ability to use a limb, irritation or picking at the bandage site, and tissue abrasions at contact surface sites with the bandage.  If any of the above listed conditions is occurring then the bandage needs to be removed, area below and around the bandage evaluated and the bandage reapplied if necessary.

Air sac cannulation

The second procedure is air sac cannulation.  This procedure is needed when access to the trachea is limited for placement of an endotracheal tube or when the presence of an endotracheal tube would interfere with any surgical or diagnostic procedure. 

The bird can be placed in left or right lateral recumbency.  Expose the area behind the last rib and in front of the leg by extending the wings over the back and forward and the legs back.  Remove a small area of feathers and do a surgical cleaning/prep. Puncture the skin behind the last rib with the #15 blade.  Use the small curved hemostat to puncture through the body wall.  Once through the muscle, open the jaws of the hemostat, widening the incision.  Inspect the area deep to the incision to ensure the region is clear and without adhesions.  Place a sterile endotracheal tube between the jaws of the hemostat and then withdraw the hemostat. A tape butterfly will aid in keeping the tube in place when secured with sutures.  The anesthesia circuit can be connected to the endotracheal tube.

Using masking tape, tape the bird positioned in dorsal recumbancy with its head facing away from you, the wings extended, and the legs pulled caudally.  Use stirrups around the tarsometatarsus of each leg to allow them to be positioned as needed for each procedure.  In a clinical setting, the bird should be positioned on a board such that the head may be elevated.  With the bird in a head elevated position, fluid will flow out of the abdomen instead of flowing into the lungs.

Dorasal cervical single pedicle advancement flap

This procedure begins with the patient placed in ventral recumbency with the crown of the head and dorsal cervical region pluck of feathers.  Please remove a circular piece of skin from the crown of the bird's head (see illustration).  Once the skin is removed make two vertical incisions from the base of the defect.  These incisions create the advancement flap.  Undermine the skin around the defect and advance the tissue flap and suture in place coving the defect using a simple interrupted pattern.

Ingluviotomy

To perform an ingluviotomy, the patient is positioned in dorsal recumbency with the head elevated and the esophagus occluded with moist cotton to prevent fluids from refluxing into the oral cavity.  An incision should be made through the skin, only over the cranial edge of the left lateral sac of the crop.  It is recommended to use a wire-tipped electrode on a radiosurgical unit, but a scalpel blade or small iris scissors will work.  The left lateral sac of the crop is less subject to stress as the crop fills and is not in a direct line of a feeding tube.  Of course in crop surgeries that involve thermal burns the surgeon does not have the luxury of choosing the location of a crop incision.  When making an incision to remove a foreign body, the incision should only be half the size needed to remove the object because the crop has an ability to stretch.  The crop incision should be made with a scalpel blade in an avascular area.  Radiosurgery forceps can be used to seal small bleeding vessels involved in the crop incision or during the separation of adhered epithelial and crop lining in a thermal burn patient.  The opening can be enlarged as needed.  Close the crop with a simple continuous appositional sutures oversewn with an inverting Cushing's pattern using 6-0 Maxon.  The skin can be closed with 4-0 Vicryl using a simple interrupted or simple continuous pattern.

Cloacapexy

The next procedure to be performed will be a cloacapexy.  A variety of techniques for cloacapexy have been described.  In this laboratory, because the normal cloacal wall is very thin, we will perform the technique which involves incorporating the cloacal wall into the closure of the ventral body wall incision.

The first thing that must be done in performing the cloacapexy is to remove the fat pad along the ventral surface of the cloaca.  This appears to be extremely important in allowing adhesions to form between the cloaca and the body wall.  If this fat pad is not removed, the adhesions quickly break down and recurrence is common.  To perform a rib cloacapexy, suture is passed around the 8th rib, then full thickness through the cloaca.  Two sutures are placed on each side and tied securely.  This will hold the cloaca in reduction.  Though you will not be able to accomplish this procedure in a normal bird, you should evaluate the anatomy and technique for performing the rib cloacapexy.  As an alternative, place 4 sutures through the cartilaginous boarder of the sternum and then full thickness through the cloacal wall.  Place a cotton-tipped applicator into the cloaca to help stretch it to the sternum.  Be careful not to incorporate the cotton-tipped applicator in the sutures.  Two sutures are placed on each side of the midline.

The body wall incision is closed by incorporating the cloacal wall in order for the suture to pass through, first one side of the body wall, then full thickness through the cloaca, then through the other side of the body wall.  In this manner, the cloaca is sandwiched within the linea alba which allows significant adhesions to form, hopefully preventing prolapse of the cloaca.  The skin is closed over the body wall in a simple continuous pattern as a separate layer.

Cloacotomy

As an alternative to a cloacapexy, you may perform a cloacotomy.  It is not feasible to perform both on the same bird in this laboratory.  This procedure is indicated for a thorough evaluation of the internal structures of the cloaca as would be necessary in treating cloacal papillomatosis.  Through this approach you will be able to visualize the coprourodeal fold and the uroproctodeal folds as well as the ureteral openings.      

Insert a moistened cotton-tiped applicator stick into the cloaca.  Using the monopolar electrosurgical tip, incise through the skin, the muscle of the cloacal sphincter, and the mucosa of the cloaca from the vent to the cranial extent of the cotton tipped applicator.  Using this technique you should not enter the coelomic cavity.  Inspect the cloacal and on the dorsal surface you should be able to visualize the ureteral openings and urine/urates flowing into the cloaca.  Closure is accomplished using 6-0 Maxon in a simple continuous pattern beginning at the cranial extent of the incision.  The vent sphincter muscle is closed with a single mattress suture of 4-0 Dexon.  Skin closure is routine.

References

Ritchie BW. Emergency care of avian patients. Veterinary Medicine Report. 1990;2:230-245.

Heatley JJ, Marks S, Mitchell M, Tully TN. Raptor emergency and critical care: therapy and techniques. Compendium. 2001;23:561-570.