The OP asked if the Horse required DSON, I answered that it did. Also almost every product page associated with the release of the New horse and accessories does say “Compatible 3D Software DSON Importer for Poser, DAZ Studio 4.5” So really people shouldn’t be in any doubt that this is indeed a DSON product.
Whether you wish or do not wish to use DSON is up to you, but it really does not have anything to do with the question the OP asked.
Please try to keep the thread On Topic. Thankyou.