This Trick Has Lost Its Cuteness

My 10-month old labrador pup has figured out a way to open two doors and let himself outdoors. Now this newfound skill would be worth applauding, except for the fact that he doesn't close the doors after himself.

Saturday morning was a case in point. I came downstairs around 5:00 AM and nearly froze to the floor. He had left the doors agape and the temperature outdoors was below minus 30 Celsius. Upon closing the doors I thought, well, if he wants to freeze his soon-to-be-surgically-removed testicles off, that's fine by me - I might even save on his airfare and veterinary fees.

I went back to bed, only to be awoken at 7:30 by a banging on the doors. By the time I got downstairs I met a rime-coated black lab bouncing around, exulting in his prodigious accomplishment of not only letting himself out, but letting himself back in.

Here is what he does: we have latched doors which are opened by pressing down on the latch, which raises a lever and unhooks the door from the strike plate. He had figured out how to open the door which swings outwards when he was only about 4 months: he simply gets up on his hind legs and bangs away at the latch until the door swings open under his weight. But the second door which swings inward until recently defeated him - the pressure he exerted upon the door would always close it before he could get out.

Here is the new approach he employs on the tricky inward swinging door. He now stands up completely straight on his hind legs, looking like lion rampant emblem on the old heraldic coat of arms. He still pounds away on the latch faster than Gene Krupa, but tries to pull the latch towards him. As soon as the door opens a crack, he gets down on this side to paw or nose the door wide enough to escape.

Before you start thinking he is some kind of wunderhund, I must report he is abysmally dull in all other respects: you throw a frisbee at him and he doesn't budge until it hits the floor, whereupon he starts kicking it around - most undignified for a retrieving dog.

So, what to do? I can't let a hyperactive pup let himself out whenever the mood strikes. Not only does this consume a huge amount of heating oil, but up here, loose dogs are often shot. A keyed deadbolt is not feasible either, since we would need seven sets of keys, one for each family member. And a conventional round doorknob is not available in the requisite size up here.

Any suggestions?