Thidwick the Big-Hearted Moose is a tale by Dr. Seuss, being one of his lesser-known works. It was published in 1948, fairly early in Seuss' career. It tells the story of Thidwick, an altruistic moose that attempts to help other forest creatures.
The book, as with almost every other Dr. Seuss books, starts with a simple premise, and a simple event: a tired bug wants to ride on Thidwick's antlers. Thidwick happily obliges, which leads to a selection of other animals deciding to hop a ride, which becomes more and more verbally and visually ridiculous as the story progresses. Then, as in other Dr. Seuss books, a climactic event happens, whereupon the situation is reset and the moral is learned.
One of the book's major differences from other of Seuss' works is the relative restraint of the drawings, both in the characters and landscape. While stylized, the animals are recognizably animals, instead of odd humanoids. The landscape is also a modest recreation of New England woods, instead of a colorful and physics-defying series of spires and canyons, as could be found in other Seuss works.
The moral of the book, if taken as a topical, political message, could be seen to be rather conservative, which is somewhat unusual for Seuss. The political message could be a denuciation of socialism and the welfare state, and could even be thought of as "Thidwick Shrugged". But it is also possibly to read the moral as a more general, non-political message about not letting people use you.
Both the art and the message might be due to this being an earlier work of Dr. Seuss, although I don't know enough about Seuss' political and personal life to make a judgment on that.
As I said after reading "I had trouble in getting to Solla Sollew", it is interesting to read a Seuss book without foreknowledge of what you are reading, and that was certainly the case with "Thidwick the Big-Hearted Moose", as well.