Share 'Doggy Doors...What to do?'

I did an audit yesterday and found out that a single doggy door was responsible for 1,300 CFM50 of air leakage (in an already-leaky house...total leakage of 5,300 CFM50 and only 2,200 square feet of conditioned floor area). So, what to do about this doggy door? I could spent some time thinking of a clever way to address this, or do some research online, but I thought of y'all first, as the preem…