it seems that the term 'bunny' has been overloaded; here's one such usage:

Obs.
[perh. a. OF. bugne, beugne, var. forms of bigne, a swelling caused by a blow; cf. boine (dial.) under BOIN v.; also BUNION.]

A lump, hump, or swelling; spec. a soft watery swelling on the joints of animals.


dust lumps??