This levels asks you to rescue 33 Pets, in 40 moves!
Only one Pet falls each move.
This means you have only 7 moves to play that are not concentrated on getting a Pet to fall.
Pets tend to come if you use a bomb and are less likely to fall if you're only removing blocks or using the line blast booster.
Concentrate on the getting as many Pets on the board as you can.
Try to use the bombs as often as you can (to encourage Pets to fall) and blow up the blocks and metal blocks from between the Pandas.
Keep count of how many Pets you have as you play.
When you get to the high 20's start using the line blaster/s to remove the bottom rows.
It is not easy, but all 33 Pets can be saved without needing to use any boosters...or if you are lucky enough to have one, get all 33 Pets on board, and use a mega-bomb!