Bertie Cosimo "the Jinx" Cow is an Anthropomorphic Cow
Bertie is a young cousin of Clarabelle Cow. He enjoys causing mischief, especially for Clarabelle and Horace whenever he visits them. For this reason, the two often call the little hellion "Bertie the Jinx" or simply "Jinx".
Behind the scenes
Bertie first appeared in 1940 in Cousin Bertie. Cosimo is his Italian name, however, in the 2016 English translation of Mickey's Inferno, he was still called Cosimo by Mickey Mouse. While the likely explanation for this is that the translaters were unfamiliar with the character, a possible in-universe explanation is that the character's middle name or nickname is Cosimo.