STANDARD PROTOCOL
Protocol for
Obtaining a Surgical Liver Biopsy from Birds
USGS, BIOLOGICAL RESOURCES DIVISION MODIFICATION DATE: January 10, 2001
ALASKA SCIENCE CENTER - BIOLOGICAL
SCIENCE OFFICE
1011 EAST TUDOR ROAD IACUC APPROVAL
DATE:________________________
ANCHORAGE, ALASKA 99503
PROCEDURE TITLE: Liver Biopsy of Birds
SCOPE: This protocol
applies to the surgical procedures required to obtain liver biopsies from
waterfowl and sea birds.
PRINCIPLE: Procedures established for obtaining liver
biopsies from pet birds usually describe endoscopic biopsies (Altman et al.
1997; Lierz 2000; Nordberg et al. 2000; Rosskopf and Woerpal 1996). These methods require expensive equipment,
are cumbersome and are not suited for field use on wild birds. The following procedure has been tested for
use in the field, and is intended to produce a sample large enough (up to 0.5
g) to allow analysis of cytochrome oxidases.
When such a large sample is not needed, consideration should be given
for obtaining a sample by the use of a Tru-Cut̉ biopsy instrument or by a fine needle
aspirate. In galahs (Eolophus
roseicapillus), 6% or 18% hepatectomy did not elevate serum bile acid
levels or liver enzymes (above those seen with celiotomy alone), and galactose
clearance tests were delayed by 18% but not 6% hepatectomy (Jaensch, et al.
2000). Liver weight as a percentage of
body weight was restored to its original value at 7 days after 6% (but not 18%)
hepatectomy.
PROCEDURES:
- Two people are necessary to obtain the
sample: a surgeon and an anesthetist.
Because of the lability of cytochrome oxidases, a third person is
required for the immediate handling of the sample.
- Standard aseptic surgical technique
will be practiced. The surgeon will wear sterile gloves, a hat, and a
surgical mask. The surgical site
will be prepared as for any surgical procedure, including plucking
feathers, skin disinfection (using povidone iodine or chlorhexidine) and
the use of a sterile drape.
- Surgical instruments should be
sterilized in an autoclave with a minimum of two layers of packaging and
stored in a dry place.
- Position the bird on the surgical
table in dorsal recumbancy with the legs extended and the wings folded. An
insulated (bubble-wrap or foam pad) cover for the surgical table should be
used to retard heat loss. Because
regurgitation of crop contents is a frequent problem, birds should be
intubated. Birds should be placed
on an elevated platform with a sloped ramp, positioning the bird’s head on
the ramp so that it is lower than the body, to avoid aspiration of crop
contents.
- A single intramuscular dose of
ketoprofen at 2 mg/kg is given during or immediately following induction
for presumptive post-operative analgesia.
- Isoflurane gas anesthetic is
administered to the bird by facemask on a non-rebreathing circuit.
Induction is at 4-5% isoflurane; maintenance is at 1-2% isoflurane in
oxygen or at a level found necessary for a given species and a given
individual. Maintenance concentrations of isoflurane may vary depending on
the individual bird and environmental variables. The bird is intubated with a cuffless tube or with a cuffed
tube without inflating the cuff. A
protective ointment may be used in the eyes to prevent drying of the
cornea. Once the abdominal air
sacs of a bird are opened, respiration can occur partially through the
surgical incision, which may require a higher setting on the vaporizer to
compensate. Once the incision is
closed, the vaporizer setting may need to be reduced. If oxygen is not
available, compressed air (optimum: >50 psi; minimum: 30 psi) can be
used to drive the vaporizer.
- An alternative anesthetic protocol is
the intravenous administration of propofol in combination with a local
anesthetic block at the incision site (Machin and Caulkett 1998,
2000). Propofol does not contain a
preservative and supports bacterial growth, so every effort must be made
to maintain the stock vial in a sterile state. Only new needles may be placed into a vial of propofol. Opened vials of propofol should be kept
refrigerated if possible. Open
vials should be discarded if aseptic technique is broken, or within 24
hours of being opened. A 25 gauge
3/8 in. butterfly catheter is placed into the tibiotarsal vein
(alternatively, a 21 gauge, 1 in. butterfly catheter may be placed into the
jugular vein. The catheter is
taped in place. Induction of
anesthesia is accomplished by delivering a slow bolus (over 1 min) of 10
mg/kg propofol. Additional boluses
of 1-2 mg may be given to attain induction and to maintain a surgical
plane of anesthesia. All birds
must be intubated, and ventilated with a bird AMBU bag. The incision site and the antenna exit
site are infiltrated with 2 mg/kg of a 0.5% solution of bupivicaine, or of
lidocaine. Mortality of male
eiders (spectacled and king) has occurred with propofol used as an
anesthetic. Until further
information is obtained, propofol should be used only with the greatest
caution in male eiders.
- Anesthesia is monitored by use of a
respiratory or cardiac monitor, or both.
Doppler ultrasound devices or esophageal stethoscopes are the
preferred monitors. An ECG is
highly recommended. Manual
palpation of a tibial or brachial arterial pulse can also be used, but is
less preferred to an attached continuous electronic monitor. Respiration is monitored by observation
of movements of the bird and the ventilation bag.
- Body temperature is monitored with an
electronic thermometer with the sensor placed either well into the
esophagus or in the cloaca. The
desired temperature range during anesthesia and surgery is 100º to 105º F.
The bird should be warmed or cooled to maintain this range. Additional heat can be supplied to a
cold bird by placing bags of warm water on the ventral surfaces of the
wings or, ideally, by the use of a radiant heat source located above the
bird. Body temperature can be
reduced by removal of external heat sources and by wiping the feet with
alcohol or cold water.
- Respiration is monitored and
mechanically supported when spontaneous breathing is less than one breath
per minute. A minimum of two
ventilations per min is made with a bird AMBU bag or with a ventilation
bag. Avoid excess assisted
ventilation to avoid delaying a return to spontaneous breathing.
- The surgical site is between the
distal end of the keel and the conjuncture of the distal ends of the pubic
bones, palpated through the abdominal wall. The feathers are plucked from the site. An area 1 cm on either side of the
incision site should be plucked free of feathers. The feathers around the site are taped
back with pieces of microporous tape.
The site is swabbed twice with povidone-iodine or benzalkonium
chloride solution. A sterile
fenestrated drape is placed over the surgical site.
- The skin is incised along the ventral
midline with a No. 11 or No. 15 sterile blade. The subcutaneous layer and
fat are sharp dissected. Once the muscular abdominal wall is reached, the
linea alba is identified. The linea alba is seized with a forceps and
lifted to permit penetration of the abdominal wall with a blade. The linea
alba is then sharp dissected with blade or scissors, avoiding the viscera,
to a length of about 2 cm.
- The caudal edge of the liver is
located in the abdomen.
Occasionally the liver is located too far rostrally to permit easy
access. In those cases, the
surgeon should pick up the bird, keeping his hands on the sterile side of
the drape, elevate the bird’s head, and shake the bird gently. The liver should drop down into
view.
- A piece of the caudal edge of the
liver is isolated using a curved mosquito forceps. The liver should fill the entire arc of
the forceps. The jaws of the
forceps are closed, but not locked, crushing the tissue. The isolated piece of liver is then cut
free by passing a scalpel blade along the inside curve of the
forceps. The cut piece of liver is
then placed on a sterile sponge and dropped onto the surgical table
outside the sterile field, for the sample processor to pick up.
- The surgeon maintains the crush of the
cut edge of the liver for about 10 seconds. Then the forceps is gently released, observing for
hemorrhage. If bleeding is
observed, the forceps are gently applied to the bleeding part and pressure
is held for another 10 sec. The
forceps are then gently removed and the cut edge observed for
bleeding. Gel foam can be applied
to the cut edge of the liver if continued bleeding is a problem.
- The surgical incision is closed in two
layers using 3-0 braided absorbable sutures on a cutting needle. The linea
alba is closed using a simple continuous pattern and the skin is closed
using either a simple continuous or simple interrupted pattern.
- The drape is removed and the vaporizer
is turned to zero. Oxygen supplementation should continue until the bird
recovers. Additional procedures such as obtaining a blood sample or
banding may be done during this period. The bird should be kept warm by
holding it wrapped in a towel until it is fully recovered. If dehydration
is a problem, subcutaneous fluids can be administered.
- Following recovery, the bird should be
placed in a cage or kennel for at least one hour prior to release. Birds should be released only when they
are alert, able to maintain head and body position, and react to human
handling. Birds that do not
respond should be carefully inspected and supportive care (heat source,
gastric intubation of water and electrolytes, etc.).
REFERENCES:
Altman,R.B., S. L. Clubb, G. M. Dorrestein, K.
Quesenberry. 1997. Avian Medicine and Surgery. W.B. Saunders Co.
Philadelphia.
Jaensch,S.M.; L. Cullen, and S. R. Raidal. 2000.
Assessment of liver function in galahs (Eolophus roseicapillus) after
partial hepatectomy: a comparison of plasma enzyme concentrations, serum bile
acid levels, and galactose clearance tests. J. Avian Med. Surg. 14(3):164-171.
Lierz, M. 2000. Endoscope-guided biopsy in birds.
Exotic DVM 2.3:17-25.
Machin, K. L., N. A. Caulkett. 1998. Investigation
of injectable anesthetic agents in mallard ducks (Anas platyrhynchos): a
descriptive study. J. Avian Med. Surg.
12 (4): 255-262.
Machin, K. L., N. A. Caulkett. 2000. Evaluation of
isoflurane and propofol anesthesia for intraabdominal transmitter placement in
nesting female canvasback ducks. J. Wildl. Dis. 36(2):324-334.
Nordberg,C. R.T. O’Brien, J. Paul-Murphy, B. Hawley.
2000. Ultrasound examination and guided fine-needle aspiration of the liver in
Amazon parrots (Amazona species). J. Avian Med. Surg. 14(3):180-184.
Rosskopf, W.J.Jr. and R. W. Woerpel. 1996. Diseases
of Cage and Aviary Birds. Williams & Wilkins. Baltimore.