This is similar to what we know happens in the UK and Ireland too.

Another reason to never leave your dogs alone outside during the day (I would not use a flap if there's the remotest possibility someone can cut through or go over a fence), and never let them out 'just for a moment' to potty outside the house without accompanying them, leave tied outside a shop or in a car 'just for a moment', etc. These thefts are so tragic and there is a real market for selling your dog.