In Kingdom Come: Deliverance 2, your canine companion, Mutt, disappears early on. This guide shows you how to find him.
Mutt's Location
While a side quest involves finding Mutt, here's a shortcut. He's near a wolf cave southwest of the Nomads' Camp, east of the river bathing spot. See the screenshot below for his precise location.

Fast travel to the Nomads' Camp. Follow the path southwest into the forest; this will lead you to the cave. You'll hear Mutt whining as you approach. He's in a clearing near the cave with some wolves.

Approaching triggers a cutscene, introducing Mutt's commands in battle. Fight or flee the wolves (fighting provides a skill-leveling opportunity). Afterward, Mutt is yours. Hold L1 (while facing him) to interact, feeding him or sending him home.
Finding Mutt During "The Invaders" Quest
You might discover the wolf cave during "The Invaders" quest, particularly if you interact with the Cumans. After drinking with them, following Vasko uphill for more liquor leads directly to the cave. This triggers the Mutt/wolves encounter, but doing this while drunk and possibly at night is considerably harder.
It's strongly recommended to rescue Mutt before continuing "The Invaders" quest. Managing wolves while drunk and in the dark is significantly more challenging.
This concludes the guide on finding Mutt in Kingdom Come: Deliverance 2. Check The Escapist for more game tips.