John B. Taylor Ceramics, which later became Louisville Ceramics in 1971, produced dinnerware and art pottery as well as promotional items for other businesses. Tracing its beginning as a producer of stoneware to 1815, it was owned by John B. Taylor from 1938 to 1970 and is now known as Louisville Stoneware. It is probably worth mentioning that prior to 1944 Mary Ann Hadley worked for John B. Taylor as a decorator.
This piece is a large, heavy stoneware mug with a bridled horse head in low relief on one side. It doesn't seem to be part of any particular dinnerware set.
Replacements.com does have listed a blue and buff horse dinnerware set but the items pictured have a design that is vaguely reminiscent of the White Horse of Uffington and nothing like this mug.
This thick walled mug is made from Indiana clay that fires buff. The weight alone (1 lb 14 oz)would almost guarantee that it is a display item rather than intended for use as a drinking vessel. The applied glaze decoration has a deliberately rustic look. The thumb rest on the handle is designed and decorated to look like an English saddle with a cinch running under it. The green line that follows both sides of the handle ends in a stirrup.
The mug was made in a mold rather than hand built. The mold line runs up the handle and up the side of the mug opposite the handle. It isn't totally eradicated but there was some effort made it finish it nicely. To the right is the cobalt undergaze stamp used to mark the mug. This is probably the last mark used by this company prior to the take over and renaming of the company. From the examples found online, the dinnerware lines for the most part continued to be manufactured with only a change in the mark. When I posted this there was only one other mug like it to be found.