Pet Rescue Saga level 64 starts off with a bit of a puzzle, a brain teaser if you will. That's good news for us, since it means we can reliably clear the beginning part. I'll share a blow-by-blow guide for the first section and some tips for the bottom half in my Pet Rescue Saga level 64 guide!
Okay, let's get this top half cleared. Your first move should be tapping the bomb, and then the three blocks under the pet.
Now, on the right side clear all the matches you can, starting from the top. This should align the right hand spring with the two upper metal blocks.
Then, on the left side repeat the process from the top, but stop with two matches left. That way, the metal boxes won't shift down and to the left, and using one spring won't clear the other.
Use the spring on the right hand side to clear the top two metal boxes. This should also remove some blocks from the left hand column, which should allow you to move the left hand spring down further.
Use the left hand spring to clear the remaining metal box which is blocking the key.
Whew! OK, now you should see another line of metal boxes with springs. What you want to do here is move one of the springs down while keeping as many of the metal boxes as possible on the same line with the other spring. In my screenshot, I can do this by clearing the two blue blocks under the right hand spring, although sadly that will orphan one of the purple blocks. Perhaps I can fix that later...
Sadly, the rest of this level isn't as predictable. You've still got one spring left to use as you see fit, and probably what you will need to do is use it to clear the metal box in the center column. There are also a couple of balloons here that can help, but make sure you deal with as much of the mesh here before you pop them for maximum effect.
The ending of Pet Rescue Saga level 64 takes some luck to wrap it up, but since you can reliably repeat the top half of this level, it shouldn't take too many lives before the blocks align properly and you can save all four pets.