In every Terminator movie & TV series, you can see that dogs barking is an indication that a Terminator (of any model) is nearby. Many dogs bark in the presence of unknowns, but in the canon dogs bark even when a Terminator isn't in front of their eyes.
As I've seen in the news, dogs have forecast earthquakes a few rare times by using their ultrasound hearing abilities. But, I don't see why this can be reason a dog recognizes a Terminator's presence without seeing it. Terminators shouldn't produce ultrasound waves to give their presence away to the human resistance & also the human resistance uses magnetic mines, not unusual ultrasound detection machines.
Why exactly do dogs bark in the presence of Terminators?
Update (after @Thaddeus 's answer):
Strange smell of 'Meat+Metal' can't be the case because dogs bark at T-1000 too.