“Hudson the Polar Bear Undergoes Physical Exam at Brookfield Zoo” by S.M. O’Connor

Last week, Hudson, the twelve-year-old male polar bear at Brookfield Zoo, underwent a CT scan and a reproductive physiologist collected semen from him into order to artificially inseminate multiple she-bears.  The Chicago Zoological Society (C.Z.S.) announced on Wednesday, April 24, 2019 that the C.Z.S. “veterinary and animal care staff were able to accomplish significant objectives during a routine medical check-up on Hudson.”

“The team was able to acquire images of the massive animal on its CT scanner and collect semen that is being used for assisted reproductive techniques with two female polar bears,” the C.Z.S. explicated.  “All the animals at Brookfield Zoo receive preventative care examinations on a routine schedule to ensure their health. These exams often include CT scans and other diagnostic medical imaging to assess internal organs and other structures. Until recently, animals weighing up 660 pounds or less were able to fit on the CT scan’s table, but an animal like Hudson, who weighs over 1,000 pounds, was simply too heavy. But, that all changed at the end of last year when the zoo was able to purchase a new table with grant funding from the Aurelio M. Caccomo Family Foundation and the Judith and Alan Fleisch Endowment Fund. This new table can accommodate animals up to about 2,200 pounds and interfaces with the zoo’s existing CT scanner, which was donated in 2016 by AMITA Health.”

“Being able to get baseline CT images on a polar bear is a significant accomplishment to advance the medical well-being for the species under managed care,” stated Dr. Michael Adkesson, Vice President of Clinical Medicine for the C.Z.S., which manages the Brookfield Zoo. “It allows us to assess Hudson’s joints, internal organs, and overall health. The images provide us with a reference to monitor his health over time and can also be used to compare to other polar bears in the future if needed.”

The team that provided medical care to Hudson include a reproductive physiologist from the Cincinnati Zoo’s Linder Center for Conservation and Research of Endangered Wildlife.  It was this person who collected semen from Hudson.

The C.Z.S. stated, “Assisted reproductive techniques are still being developed in polar bears, but hold great promise for the overall population of this species in zoos. Polar bears breed seasonally and only produce one to two cubs per year, so there is a lot of interest in developing assisted reproductive techniques to aid the rate of successful breeding. The process of transporting semen is a lot easier than transferring bears between facilities and can also increase the chances of a female becoming pregnant.”

“The development of assisted reproductive techniques have aided the recovery of many endangered species,” stated Dr. Adkesson. “These techniques have worked well in developing sustainable populations of other endangered bears like the giant panda; we hope to someday see similar success with polar bears.”

After confirmation that the semen sample was viable, C.Z.S. veterinary staff inseminated Nan, the female polar bear at Brookfield Zoo.  Meanwhile, Cincinnati Zoo staff transported some of the semen harvested from Hudson to the Henry Vilas Zoo in Madison, Wisconsin to inseminate one of the females there.

“The remaining collected semen will be frozen for use in the future,” the C.Z.S. stated.  “With the future of the wild polar bear population being more and more threatened by climate change and the loss of arctic sea ice, it is crucial to do everything possible to ensure the survival of the species so that future generations are able to experience seeing these iconic North American mammals.”

Polar bears are currently listed as a vulnerable animal species on the Endangered Species Act of 1973, which was the enabling legislation for two agencies of the U.S. Government – the United States Fish and Wildlife Service and the National Marine Fisheries Service – to enforce the international Convention for International Trade in Endangered Species for Wild Flora and Fauna.  According to the International Union for Conservation of Nature (I.U.C.N.), conservation actions are necessary for the survival of polar bears.

01fc345b-ee82-4399-b751-db89b13e6ac5Figure 1 Credit: Chicago Zoological Society Caption: Chicago Zoological Society veterinary staff position Hudson, Brookfield Zoo’s 12-year-old male polar bear, in preparation for a CT scan.

74e3fb1f-c4fb-4cd2-a547-2972722d4045Figure 2 Credit: Chicago Zoological Society Caption: The Brookfield Zoo acquired a new table that interfaces with its CT scanner and can accommodates animals up to 2,200 pounds, including Hudson.  He weighs just over 1,000 pounds.

91e2fcfa-f43f-41aa-970e-de29d8b48348Figure 3 Credit: Chicago Zoological Society Caption: Dr. Marina Ivančić, veterinary radiologist for the Chicago Zoological Society, takes an ultrasound of Hudson, Brookfield Zoo’s twelve-year-old male polar bear, during a physical examination.


The C.Z.S. is a private, non-profit organization that operates Brookfield Zoo on property that belongs to the Forest Preserves of Cook County (formerly called the Forest Preserve District of Cook County).  The Website is www.CZS.org.  The Associations of Zoos and Aquariums (A.Z.A.) accredits the Brookfield Zoo (as well as the Lincoln Park Zoo and the Shedd Aquarium).

The Brookfield Zoo is located in west suburban Brookfield, Illinois, approximately fourteen miles west of downtown Chicago.  The address of the North Gate Main Entrance is 8400 31st Street, Brookfield, Illinois 60513.  This is on 31st Street, west of 1st Avenue (and thus the Des Plaines River).

The address of the South Gate Main Entrance is 3300 Golf Road, Brookfield, Illinois 60513.  This is west of Riverside Brookfield High School.  It is within walking distance of the Hollywood Stop on the Metra’s B.N.S.F. Railway, which runs between Chicago and Aurora.



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