"What American Airlines is doing is discrimination," said attorney Reginald McKamie, Sr., who is representing Texas man Dana Holcomb in a case against the travel operator.
The search is underway for the family's beloved dog Logan.
"The safety and security of Delta people and our customers is always our top priority. We will always review and enhance our policies and procedures to ensure that Delta remains a leader in safety."
This latest incident came as airlines across the U.S. were cracking down on emotional support companions.
Dexter didn't make it on the plane, and neither will fake service animals.
This incident inspires a flurry of questions, and the answers are complicated.
Ryan Boylan saved the squirrel last year and named her Brutis.