If your dog steals things, then don’t play, the idea is for your puppy to learn that taking your things is completely pointless because it doesn’t result in anything fun happening to them as a result. Provide physical and mental exercise, your dog might be stealing things because they are looking for something to do or for some interaction with you. Dogs need both physical and mental stimulation to prevent boredom. Make sure the stealing behaviour is not rewarded, dogs will repeat anything that works out well for them, so if your dog enjoys gaining your attention by stealing things, the best thing to do when they steal is to ignore them, as long as it is safe to do so. Simply wait until they lose interest and drop the item, then encourage them to do something else instead, such as play with a toy or enjoy a chew. If possible, try to avoid picking up the item straight away as you don’t want your dog to think it’s valuable because you appear to be desperate to have it.
Be prepared for things to get worse at first, when you start to ignore your dog for stealing things, you might find that they appear confused, especially if this behaviour would have previously resulted in you jumping up and chasing them in order to get the item back. A dog might try even harder to get the response they are expecting, so you might initially see your dog stealing more items. Always reward good behaviour, make sure you give your dog lots of praise and attention for good behaviours instead, like playing with their own toys or relaxing by themselves. Teach your dog to swap things, it can be useful to get your dog comfortable with swapping something they have for something they consider to be of equal or greater value.
When your dog takes something that’s valuable or that could harm them – for example, a packet of tablets – then try making a distraction that does not involve talking, touching or looking at them, you could walk out of the room to see if they follow you or make a noise by opening a door. Once your dog has dropped the item and moved away from it, get them involved in something else, scattering a handful of treats for them to sniff out in a different room will keep them pleasantly occupied so you can pop back and move the stolen item to a place of safety.