I think the first ever adaptation of any Dr. Seuss book was the 1942 Merrie Melody cartoon, Horton Hatches the Egg. Directed by acclaimed LT director Bob Clampett, this short is remarkably faithful to the doc's original story while still implementing some humorous Warner Bros. Style antics to balance it all out.
Apparently, Clampett and his team didn't even produce a storyboard / script from scratch and instead used his own copy of the book as a blueprint for additional material to include, most of which are the kind of juvenile gags you'd see in any Clampett or Tex Avery cartoon during this time. Having said that, the primary focus of Horton the elephant being used to sit on an egg from a lazy irresponsible bird named Mayzie remains intact quite nicely. The initial themes of staying faithful to someone and maintaining trust in spite of being a laughing stock are still prevalent and thus make Horton a truly sympathetic lead. While there could be an argument about how Mayzie is portrayed from a feminist perspective, the idea that some people can be more responsible than the initial parent remains as timely as ever. Add in some humorous Looney Tunes content for extra levity and you've got the longest running WB short made in the Golden Age without it feeling long at all.
On a side note, the late Kent Rogers voiced Horton himself, and while the short is carried through Frank Graham's solid narration and Sara Berner's hysterical portrayal of Mayzie, his genuine emotional delivery makes Horton far more empathetic than the Doc and Bob Clampett already made him out to be. Rogers sadly parted this world not long after the cartoon was released, so hearing him as such an innocently devoted elephant really hits home. I only wish he could have done more beyond his work at Warner Bros and other studios, but we'll always have works like this to remember him by.
I don't think I have much else to say, but Horton Hatches the Egg still holds up today. It's a charming blend of two different styles, with Seuss's content and Clampett's humor stretching for miles. Definitely give it a watch if you might, I'm sure you'll find some value in this cartoon alright. I meant what I said, and I said what I meant, this short is worth the watch, 100 percent.
