Edith Lombardo-Albach said she took the dog to New Jersey's Liberty Newark International Airport in January and handed him over to United Airlines workers to have him sent to join her husband and daughter Thursday in Phoenix, ABCNews.com reported Monday.
"They marked everything Phoenix, and put the tags on Phoenix," she said.
However, Lombardo-Albach said she got a call Thursday evening from the airline saying the 6-year-old English Springer Spaniel, Hendrix, had been placed on the wrong flight and was headed to Shannon, Ireland.
"I almost fainted," she said. "My husband and my daughter were already at the airport waiting for the dog."
Lombardo-Albach said United promised her Hendrix would be cared for and returned.
"They were going to have someone clean the dog, feed the dog, walk the dog, and then they were going to get the dog back on the plane and send him to Newark," she said.
"The dog had already gone seven hours to Ireland, and now the dog has a two-hour layover and then a seven-hour flight to Newark," Lombardo-Albach said. "I was insane."
Lombardo-Albach said she greeted Hendrix when he returned to Newark and spent time with him before he boarded the right plane to Phoenix.
United apologized for the incident and refunded Lombardo-Albach's money.
"We are reviewing the circumstances surrounding the situation and will take steps to prevent this from happening again," she said. "Hendrix's experience is not typical of the service we provide to the more than 100,000 pets who travel with us every year."