Cleveland Browns Urged To End Live-Mascot Tradition After Swagger Jr.'s Death

PETA's imploring the Cleveland Browns to do away with their live-mascot tradition following the death of their sideline dog ... telling TMZ Sports it believes the practice is harmful to animals.

Tracy Reiman -- PETA's executive vice president -- made the urging on Tuesday afternoon ... just hours after the NFL org. revealed its bullmastiff mascot, Swagger Jr., had passed away at five years old.

Reiman said in a statement that "generations of breeding for a certain look have left bullmastiffs prone to hip dysplasia, cancer, and life-threatening heart issues, among other painful conditions." She added that she believed Swagger Jr.'s death "should be seen as a damning indictment of an industry that deliberately churns out these doomed breathing-impaired breeds."

Reiman then implored the Browns to go a different route with their mascots in the future ... urging them to instead simply "adopt a logo featuring a brown mixed-breed dog from an undoubtedly overwhelmed local animal shelter."

Swagger Jr. worked the Browns' gamedays for nearly the entirety of his life ... after the pup's father, Swagger, had previously held the position from 2014-19.

The Browns said in a statement Tuesday morning they were saddened by the dog's passing, though they did not release a cause of death.