Would it be possible to use "лаются" and "кусаются" in this context to emphasize that you're talking about a general tendency? As in Собака кусает меня за руку ("The dog is biting my hand") vs. Осторожно, эта собака кусается ("Beware, this dog has a habit of biting").
For some reason, though, LOTS of English-language textbooks refer to the деепричастие as a "gerund" -- even though, as you say, the деепричастие is adverbial in nature, while the "gerund" is a noun in both English and Latin.
(Hmmm, from Googling, I find that in some Romance languages like French and Spanish, the Latin gerund eventually lost its noun-ish nature and developed an adverbial function. So presumably the influence of French explains why "gerund" is used for the деепричастие.)