From hummingbirds to bears, there is often something interesting (and a bit gory) on the steel tables in the necropsy laboratory.


Stacie Nellor handed a stainless steel bowl up to the first person in the front row of the viewing gallery. In the bowl was a feline abdomen that contained a large tumor. The specimen was passed among a group of two dozen students while Nellor explained the source of the cat’s abdominal bleeding: a rare disease called Factor XI Deficiency.

Nellor is a fourth-year veterinary student working in the necropsy lab where, among other things, she performs animal autopsies (called necropsies) under the supervision of a pathologist. Nellor saved the cat’s remains to present at the Wednesday morning necropsy rounds. The rounds are open to any student or staff of the Carlson College of Veterinary Medicine, and sometimes visitors on guided tours attend as well.

The necropsy lab is one of the busiest services at the Oregon Veterinary Diagnostic Laboratory (OVDL). In addition to educating students, pathologists perform necropsies for veterinarians, pet owners, and farmers, and work closely with many government agencies from Oregon Public Health to the U.S. Department of Agriculture.

Dr. Rob Bildfell is an OSU professor, a board-certified pathologist, and supervisor of the necropsy service. In his twenty years at the lab, he has seen a wide range of interesting cases involving many different species, and a lot of those came from the Oregon Department of Fish and Wildlife (ODFW).

From big bears to tiny hummingbirds, ODFW is interested in knowing why animals have died. “Typically they send us species that are of interest to their clientele, like deer, elk, and ducks,” says Bildfell.  “Or they may be concerned about disease transmission when an animal has had contact with humans, like a wild rabbit that a Good Samaritan has tried to help.”

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A small lab at OSU is a critical component of the state’s complex system that protects the public from rabies.


Wendy Black has been testing brain tissue, looking for rabies infection, for twenty-six years. She and fellow technicians process about 80 samples every week. They work for the Oregon Veterinary Diagnostic Laboratory (OVDL), the only lab in the state that does rabies testing.

The laboratory space for rabies testing resides in a seventy-year-old building on the western edge of the OSU campus. The faded, old linoleum on the floors is in stark contrast to state-of-the-art equipment set up throughout the building. Most of the rooms contain automated processers conducting sophisticated diagnostic testing, but the rabies lab follows a Center for Disease Control (CDC) protocol that has been the standard for decades, and it’s all done by hand.

When a dead bat comes into the OVDL, the first thing Wendy does is remove its brain. “We separate the cerebellum and brain stem; that’s where the concentration of rabies will be found.”

Wendy prepares a slice of brain tissue by fixing it to a slide then treating it with two different kinds of rabies antibodies. “Essentially, we have two different agents looking for the same thing,” she says. This is one of many steps they take to ensure accurate diagnosis.

The slide sits for thirty minutes, letting the animal tissue and antibodies incubate together, then Wendy uses a microscope to view the result. She looks at forty different tiny sections, searching for a grouping of bright green spots called ‘green apple granules’, the evidence of rabies. Her colleague duplicates the process with the same brain tissue to make sure they are not missing a low-level infection. There is absolutely no automation involved; it’s just people working efficiently, and time is a factor. “From the time of receipt to the time of reporting, we can usually get it done in 2-3 hours,” says Wendy. “We want no more than a 24-hour turn around, for peace of mind of the clients.”

Most rabies testing at the OVDL is done on dead bats (only about 30% is done on larger animals) and most of those bats come from the general public.  When a slide tests positive for rabies, the OVDL contacts the state veterinarian at the Oregon Health Authority, who notifies the county where the animal resided. He may also question the person who found the animal to determine if anyone was exposed and needs treatment, a process that involves many weeks of shots.

When a slide tests negative for rabies, Wendy quickly contacts the person who submitted the bat. “I like to call them personally with the negative result,” she says. “They might be worried about exposure to their pets and family, and it is nice to hear the sigh of relief in their voice.”

In cases where a dog or cat brings home a dead bat, or when a veterinarian suspects a pet’s neurological symptoms may be due to rabies, there is only one sad, stressful way to diagnose the disease: euthanize the animal and remove its brain. However, the CDC has recently developed a promising, new rabies test that uses tiny DNA samples instead of brain tissue. “It will be very sensitive,” says Wendy, “And the neat thing is they can use it on different kinds of samples, like saliva, so the animal would not have to be euthanized.”