Friz (or "I.", of you will) Freleng's "Curtain Razor" was made around the time that Warner Brothers stopped populating their cartoons with humanoid "funny animals" and started using animated humans, except for series regulars like Bugs Bunny or Daffy Duck, or when the setting (e.g. a chicken farm) demands a certain type of animals (chickens, a guard dog, a fox or a weasel) as the main characters.
In this cartoon, Porky is a talent agent working for Goode and Korny, auditioning performers of various species.
Sometimes their species is an important part of the joke, sometimes it isn't. In the first category, we have a cricket or grasshopper with a loud, strong voice; a chicken who "lays an egg"; and a sheepdog with a flea circus. In the latter category we have the turtle with "a thousand voices"; the Crosby, Sinatra and Jolson birds; the goofy dog with the high-dive act... and, of course, the fox who blows himself up. We also have two humans... a two-headed guy who isn't in show business (he's the janitor) and "Cawford Coo" with his trained pigeons. Things get a bit blurred and confused: Porky thinks that the sheepdog (who walks on all fours, but enters by himself and speaks) is a "dog act" but doesn't assume the same of the high-diving bipedal dog in the bathing suit.
Contrast the two gags which Freleng would later re-use in 1957's "Show Biz Bugs. In the later cartoon, both the "Trained Pigeons" act and the "explosion" act were performed by Daffy Duck. But in "Curtain Razor", it was probably deliberate that one is performed by a human and one by a humanoid animal. It's probably better that "Crawford Coo" is a human, as the joke comes from the fact that the realistic pigeons behave just as real, untrained pigeons would (contrast the flea cricus in the same cartoon!) However, even though it isn't really important to the gag whether the guy who blows himself up is a fox or not, if the fox who blew himself up were human, it would probably be way too gruesome, and Freleng and his storymen may have decided that a gag like that should be left for imaginary beings like anthropomorphic animals, to keep it in the realm of the fantastic... no pun intended!