Kara Swindle was supposed to pick up her German Shepard, Irgo, at a cargo facility in Kansas City, Missouri, Tuesday afternoon, she told ABC News.
When she arrived, an employee told her a "beautiful Great Dane" was waiting.
She said that's when she started to worry about her dog.
Apparently, the airline's crew had mixed up Swindle's German Shepard with a Great Dane bound for Japan and sent both dogs to the wrong location.
"An error occurred during connections in Denver for two pets sent to the wrong destinations," United said in a statement. "We apologize for this mistake and are following up with the vendor kennel where they were kept overnight to understand what happened."
The airline said it's flying Irgo back to the U.S. in first class, according to Swindle.
This mix-up comes after a puppy died on a United flight Monday after a flight attendant ordered the owner to place the dog in the overhead bin.
Editor’s note: The spelling of Swindle’s last name has been corrected in this story.