Blind in one eye, with an old injury to its left wing, Gladys Porter Zoo officials said the bird can fly short distances but it can't survive on its own.
The eagle's impaired vision make it unable to judge distances well and zoo staff fear it might be hit by a car if it is not quickly found.
The female bird is about 3 feet tall and weighs 10 pounds. It has a white head and tail, a dark chocolate brown body and yellowish beak.
Zoo officials are asking for help in finding and returning the eagle to their aviary, where it has lived since 2005.
The Florida Audubon Center for Birds of Prey in 2005 determined that the eagle was an unlikely candidate for release after it was admitted for treatment. They sent the bird to the zoo.
"We're not exactly sure where it is," zoo spokeswoman Cynthia Garza Galvan told the Brownsville Herald for its Friday online editions.
She said that the eagle is on a feeding schedule so they had hoped it would return when it got hungry but it hasn't yet.
Slideshow archive | ABC13 wireless | Headlines at a glance