According to an incident report, a passenger identified as "Mr. Mundy," a current military service member, had an emotional support dog with him while boarding his flight from Atlanta to San Diego.
When Mundy and his 4-year-old chocolate lab-pointer mix took their seat next to another passenger identified as "Mr. Jackson," the dog allegedly attacked Jackson.
Jackson suffered multiple bites and was transported to the hospital in stable condition with severe injuries to his face, according to the report. The dog has been vaccinated for rabies.
In a statement, the airline confirmed the incident. "Prior to pushback of flight 1430, ATL-SAN, a passenger sustained a bite from another passenger's emotional support dog. The customer who was bitten was removed from the flight to receive medical attention.”
Passenger Bridget Maddox-Peoples told Fox affiliate WAGA, "There was a call for help, you could hear a dog growling and a bark and someone scream, 'I need help, there's a medical emergency!'"
Maddox-Peoples added that the man's face and shirt was covered in blood.
Delta later re-accommodated Mundy on another flight, but this time with the dog in a kennel, according to the airline.
It's unclear if Mundy is facing any charges. ABC News' attempts to reach Mundy and Jackson on Tuesday were unsuccessful.
ABC News' Erin Dooley, Henderson Hewes and Rachel Katz contributed to this report.