Polar Bear Ultrasound

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Will these two become parents this year?

Pieces of the Puzzle

Yes, we have begun the ultrasound exams with Chinook! Yes, she is cooperative, and we are very hopeful that this will be the year that once again we will have polar bear cubs at the San Diego Zoo. But how difficult is it to ultrasound a polar bear who is wide awake? The pieces of the puzzle are coming together.

The first puzzle piece, training, was relatively easy. Due to the great trusting relationship between Chinook and her keepers, and the history of learning together, teaching Chinook to roll over and hold went quickly. The next part was to get her to accept the ultrasound gel and actual probe on her belly. Chinook does very well with it all. And please keep in mind she is the only polar bear in the world who is trained for the ultrasound procedure.

We tend to take for granted the use of ultrasound to diagnose pregnancy. It is almost commonplace now. It wasn’t that long ago when ultrasound exams on our giant panda Bai Yun were also history in the making! Again one of the challenges is to find a very small fetus in a very big bear and ensure the safety of Chinook, the veterinarian, and, of course, the ultrasound probe! We are lucky to have many talented folks at the Zoo who have helped in designing and building various pieces of the puzzle. We now have a specially molded probe holder and removable bars on our training crate that allow for better movement of the ultrasound probe.

Every ultrasound image is recorded for review by our veterinary staff. We are confident that “when” (positive thinking) polar bear cubs begin to develop, we will be able to see them well and document another historical event: first-ever in utero polar bears!

Until then, we continue to collect urine and fecal samples to chart Chinook’s hormonal changes and monitor her behavior for dramatic and subtle changes that will alert us to her needs for a successful pregnancy and rearing of polar bear cubs. The cameras, microphones, and recorders are all ready, as long as she chooses those areas to den!

Now that we have all the pieces to the puzzle for our Chinook, it is important to remember that there are many pieces of polar bear reproduction that are missing. Much of our research with polar bear sensory ecology (see post Polar Bears: Getting Ready) will help shed light on pieces of the puzzle that would be very difficult, if not impossible, to do in the Arctic. To be able to document a polar bear pregnancy may give us more information on how to better protect polar bear maternity areas at critical times as more environmental impact jeopardizes the survival of our wild polar bears. How wonderful to be part of keeping polar bears in our future and not just a part of our history.

JoAnne Simerson is a senior keeper at the San Diego Zoo. Read her previous post, Polar Bears: Dare to Hope.

Update October 28, 2011: Both ultrasound and fecal hormone analysis look possible, but nothing is confirmed yet. Keep everything crossed!