Here is the full list of all 21 Little Dog achievements.
Collect 40 bones
Click on "Menu"
Click on "Play"
Click on "Exit"
Jump 100 times
Die 30 times from cliffs
Die 30 times from bat
Die 25 times from plants
To be at level 5 for more than three minutes
Reach level 12
Reach level 11
Reach level 10
Reach level 9
Reach level 8
Reach level 7
Reach level 6
Reach level 5
Reach level 4
Reach level 3
Reach level 2
First level started