dustball

plural dustballs

1. A ball of dust.
2. archaicA ball of grain-dust formed in the intestine of a diseased horse.

   1 more example

   Long residence in lime districts had furnished the experience, that phosphatic calculi are not even as common as among the horses and ponies of coal-mines; and, further, that both phosphatic calculi, and more generally mixed or the dustball kind, are very prevalent in those pits, and even districts above ground, where no lime-water whatever can be obtained.

   1885, George Armatage, Every Man His Own Horse Doctor, page 336