ABDOMINAL IMPLANTATION OF HEART RATE TRANSMITTERS INTO GEESE
MARCH 4 1998 UPDATE: SEE BOTTOM OF PAGE
Note: The results of the helicopter study mentioned here will be reported by the biologist at a separate venue.
Background: The U.S. Army wishes to train its combat helicopter pilots to fly low and fast over the ground. Apparently, they survive longer on the battlefield if they stay low. One of the desired training areas in Alaska also happens to be the nesting grounds of the white front goose. Merely watching the geese sitting on their nests while a helicopter flies over isn't a good technique because: 1. the geese are already disturbed by the presence of the observer, 2. nesting geese are difficult to observe from a distance because their nests are located in tall vegetation, and 3. a disturbed goose may react by freezing, which makes documentation of the level of disturbance difficult. In an effort to determine the level of disturbance. Determining a physiologic response to disturbance, such as elevation in heart rate, and using telemetry to send the heart rate to a receiver avoid these problems.
Heart rate transmitters have been used in other studies of disturbance and physiology of mammals and birds. The methods of attaching both the transmitter and the leads vary from study to study. Here I present pictures showing several steps in the surgical implantation of the heart rate transmitter and attachment of the leads.
The geese were captured on the nesting ground by herding them into a trap and by using hand nets. They were flown back to Anchorage for the surgical implantation of the heart rate transmitters. The birds were given an oral nutritional supplement and fluids, and were held overnight before surgery was done.
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Anesthesia is induced and the birds are prepared for surgery in much the same way as for abdominal implantation of radio and satellite transmitters. An extra site is prepared over the left clavicle just lateral to the sternum.ç Note the cloacal temperature probe (white) and the Doppler ultrasound attachment to the left leg. |
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Above, Pam Tuomi, D.V.M. (right), and anesthetist Celia Hall, CAE, SRA (left), implant a goose. The backs of the anesthesia machine and the ECG monitor are seen in the foreground. |
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The transmitter is inserted into the right abdominal air sac. The transmitter body is enclosed in a tight-fitting bag of surgical mesh. The surgeon sutures the mesh to the body wall, which holds the transmitter in place. The antenna is internal in the transmitter body. |
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The caudal lead is attached by suturing it to the dorsal aspect of the caudal end of the sternum. This lead will lie totally within the abdomen. |
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The anterior lead is passed under the skin to the thoracic inlet. We use a polypropylene, 10 gauge, catheter to create the passage. The closed end of the catheter is pushed anteriorly under the skin. One hand advances the catheter and the other pushes down through the drape on the catheter tip to guide it and to prevent it from pushing up through the skin. Once the tip is pulled out through the prepared area at the thoracic inlet, a sterile wire is retrograded through the catheter. |
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The wire is attached to the end of the lead, which is then wedged into the flared end of the catheter. This protects tissues from damage. The entire catheter with the inserted lead is pulled forward under the skin. The wire is detached from the lead, which is then sutured to the left clavicle just lateral to the sternum. The skin incision at the thoracic inlet is sutured closed. The body of the transmitter is sutured to the body wall in two places to prevent the transmitter from moving inside the bird. The abdominal incision is closed in two layers and the bird is recovered from anesthesia. |
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MARCH 4 1998 UPDATE
: The transmitters were programmed to shut down during southward migration of the geese to preserve battery life. In December, the transmitters switched back on and 12 implanted birds were detected at the Sacramento National Wildlife Refuge in California. Seven of the 12 birds continued to give a high quality heart rate signal, while the rest were intermittent, the signals were poor quality, or the transmitters were silent. Additional birds may be elsewhere, out of the range of the receivers. As of the end of March, 1998, at least a couple of the implanted birds had been shot by hunters.
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