There are 4 dogs to find in Exophobia, one in each floor of the ship. When you find a dog, you can pet it by pressing the action button.

Petting all four dogs will unlock the 'Woof woof!' achievement.

Floor 1 - To the north side of the save point, use a charge shot to destroy the wall and reveal a secret area. Don't forget to pet!

Floor 2 - In the 101 chamber, use a charge shot to destroy the wall under the zero. Don't forget to pet!

Floor 3 - In the prison area, enter the cell and use a charge shot to destroy the wall to the east. Don't forget to pet!

Floor 4 - Use a charge shot to destroy the wall under the mirror. Don't forget to pet!