Fleischer/Famous Animation Studios artist, Chad Grothkopf, left comic book packaging studio, Funnies, Inc. in mid 1941, to form his new, own studio, to subcontract with Fawcett Comics, to produce all their funny animals series (starting with "Fawcett's Funny Animals). Along with himself (credited as Chad Grothkopf, "Chad", and "Alex Kotsky", his studio's other artists were: Bill Brady, Don Gunn, Al Jaffee, and Allen Ulmer. In the later years of that series(1949-54), it appears that he added a couple other artists, as based on the style of "Slinky Stinky", it doesn't appear to have been drawn by any of those artists I listed above. (unless it was Ullmer, whose work I don't know very well)
Link to the book:
Fawcett's Funny Animals 83