Because moves are very limited in this level it is essential to start the level with a helpful board.
Before you make any moves, check the position and color of your blocks.
You will need to be able to drop a rotoblaster down three blocks (to break the mesh from the key)
And you will need (on the opposite side) to have a block the same color as the Pet carrier below it, in a position that you can get it down to the bottom row with the other rotoblaster directly on it.
This might sound complicated, but you will see it is the optimum board to play with, and if these factors are not there in the beginning, it isn't worth continuing.
Break the mesh off the center block with a rotoblaster, then unlock the key.
This should build up a balloon booster...use this to pop the color of the center Pet carrier.
Now the line blaster will be level with the second row of metal boxes and they can be destroyed.
Next, you need to get the other rotoblaster to the bottom row. Hopefully you will have the correct color block/s to do this (as checked before you started playing)
Once the bottom row is gone, it's just a matter of dropping the Pets ....and hoping you have enough moves left to do it!