Dog-proof cat-flaps?

[wheaten]

Are there any? Whn my dogs go off on one, they stick their heads out and break it, on second flap alrady this year (Staywell). Have now just had to put this one back together again (took half hour to do) as Floyd had 3 pieces wrapped around his head! I can't lock it as he'll just bash it so I've put a heavy bin in front of it but have to leave enough space for cats and he still gets through. Did try magnets but they don't work as door has a steel inner and h'll just bullet through that as well, vey determined!
Short of locking dogs in diferent rooms (they whine), any ideas?
Many thanks

[boxtops]

Have you looked at the catflaps which work off the cats' microchips? The flap wouldn't open unless it is programmed to the individual chip, so Floyd wouldn't be able to make the flap move (in theory). Otherwise, why not get a small dog flap? then everyone can get in and out!

[lankeela]

Get one that goes in glass, and put it in a window where the dog can't reach.