How does pet damage scale?

I’ve been playing some pet builds and the damage scaling is unclear to me. A level 16 Hellhound has +180% pet damage. How does that add with other pet bonuses? Say I have another 50% from a devotion. I assume that’s just added to the 180%.

The Hellhound skill says that it does about 200 damage with the basic attack. But when it hits enemies, the actual damage is about 1500. I’m guessing that the listed damage is before any pet bonuses, including the bonus on the Hellhound skill itself?

My character for context: Sentinel, Level 30 (GD 1.2.1.6) - Grim Dawn Build Calculator