Bald Eagle Recovers from West Nile Virus

Apr 21, 2015 / Disease / eagle / Wildlife

[three veterinary students with an eagle]

After three weeks of treatment, the eagle was ready to leave the Wildlife Medical Clinic

The large bird discovered on the side of a gravel road in Effingham, Ill., was not moving much and didn’t seem to use its wings or legs. A closer look revealed that the bird was a bald eagle, the national bird. The eagle’s rescuers brought it to the Wildlife Medical Clinic at the University of Illinois Veterinary Teaching Hospital in Urbana, where a team of veterinary students assessed its condition. (In the photo, Malky Spektor, Melissa Giese, and Maddy Erba pose with their regal patient.)

“Bald eagles are found only in North America,” says Dr. Julia Whittington, medical director of the wildlife clinic. “They have a wingspan of six to eight feet and weigh between 10 and 14 pounds. The females are larger than the males. They can live up to 25 years in the wild, and their characteristic white heads and markings appear when they are about four years old.”

Fifty years ago, bald eagles were listed as endangered in some regions, including the southern half of Illinois. At that time, eagles were hunted for sport, and their numbers were decimated by pesticides, such as DDT, that they ingested in the fish they ate. However, conservation efforts were successful, and in 1999 the bald eagle was removed from protection under the Endangered Species Act.

“Today eagles are very common in Illinois, especially around the Illinois and Mississippi rivers,” says Dr. Whittington.

The eagle brought to the Wildlife Medical Clinic was dehydrated and had diarrhea. He could not hold himself up and did not exhibit the normal instinct to resist being handled by people, which was very concerning. The eagle was given fluids daily to combat the dehydration, and was tube fed to ensure he was getting appropriate calories, since he would not eat on his own.

It was difficult to tell what was causing his illness, but Dr. Whittington suspected West Nile virus. Birds of prey can acquire the virus from eating infected birds.

“Clinical signs associated with West Nile virus infection in birds range from unexplained death to eye disease to neurological problems such as dizziness, weakness or paralysis,” says Dr. Whittington. “The only treatment for a viral disease is to provide supportive care such as fluids and pain relievers to decrease the inflammation associated with infection.”

Recovery can take several weeks or months, and some of the neurological issues can be permanent.

After a few days of treatment the eagle began to stand on his own. He became feistier with the care team, showing he was regaining strength.

To determine a diagnosis, Dr. Kenneth Welle, an avian specialist at the Veterinary Teaching Hospital, completed a laparoscopic biopsy of the eagle’s spleen, liver, and kidney so that these tissues could be tested for West Nile virus.

“The tissues most commonly affected by this virus are the brain, the heart, and the kidney. We can’t safely biopsy the brain or heart, which leaves the kidney,” explains Dr. Whittington. “We also biopsied the liver and spleen because these blood-filtering organs provide information about other potential pathogens, such as bacteria.”

Immediate test results were inconclusive; the liver showed mild inflammation, indicating an infection. After a few days for processing, the test for West Nile virus came back positive.

After 12 days of supportive treatment, the eagle began eating food on his own. He was gaining strength daily and began exhibiting behavior appropriate for a wild bald eagle, such as vocalizing and fluffing his feathers to appear more threatening. Though this growing aggression made it difficult to treat the eagle, the care team was very happy to see him feeling better. Handling was kept to a minimum to keep the eagle as stress-free as possible.

After three weeks of treatment, the eagle was ready to leave the Wildlife Medical Clinic for a rehabilitation facility, where he was tested for flight and hunting capability before at last being released into the wild.

“The University of Illinois Wildlife Medical Clinic is a tremendous resource to the central Illinois community,” says Dr. Whittington. “By caring for injured and ill wildlife without cost to the presenter, we are able to help animals that would not otherwise receive care, with the goal of releasing them back to the wild. The animal’s needs are our priority, even if in some cases the appropriate care is a humane end to the animal’s suffering. Through clinic involvement, we give veterinary students valuable experiences that enhance their professional skills and career. We rely on financial contributions from the public to carry out this work.”

By Melissa Giese