[1] In English and many other European languages, the principal means of distinguishing between multiple third-person referents is using gender or (lack of) reflexive.
If the fox is the more important one, the sentence might look something like "the quick brown fox-PROX jumps-PROX>OBV the lazy dog-OBV", where PROX>OBV is verbal inflection indicating a proximate subject acting on an obviative object.
On the other hand, if the dog is the more important one, the sentence might look something like "the quick brown fox-OBV jumps-OBV>PROX the lazy dog-PROX", where OBV>PROX is verbal inflection indicating an obviative subject acting on a proximate object.
By contrast, an equivalent subsequent sentence in English, such as "and then he went away", would not necessarily indicate whether "he" is the fox or the dog.
[3] Obviate/proximate distinctions are common in some indigenous language families in northern North America.
Obviation is not overtly marked in Ingush but is implied, as certain constructions are impossible unless one referent has salience over another.