I have a nine week old GR puppy who, when awake, is into everything and I'm trying to dissuade her from chewing unsuitable things. Dug out the kong and looked into smearing simple things round the inside edges to keep her interested. Not done this before with such a young dog and don't want to overload her immature digestive system, although it seems fine on the diet of dead leaves and moss at the moment. I smeared a little bit of honey which she was thrilled about and plan to try low fat unsweetened yoghurt next time. Any hits and tips for such a youngster? Also worried about leaving bits of foods inside the kong, how do you clean the things?

I have used peanut butter or cream cheese, both of which the puppies (7 weeks onwards) and dogs love, to no ill effects.  Don't worry about cleaning them, the dogs do that for you - they love them, lol  :-)   Seriously though, I soak mine in water if there are areas the dogs miss.

Like Megslegs I have used cream cheese and peanut butter - just smearing a little all round the inside of the Kong.  The cream cheese you get in a tube works well.  Very popular!  I have also used part of the puppy's meals to fill the Kong.  I just soaked and then mashed up some of the kibble and packed it in.  (I still do this for my adult dog with a large heavy duty Kong and then freeze the whole thing for a little while to 'set' the filling.  He loves it and spends ages extracting all the filling).

I soak/rinse the Kongs and then put them on the top shelf of the dishwasher and they come out spotless.  I think Kongs are great.  Have fun!

Ah ha, dishwasher, of course. Why didn't I think of that!

Thanks Megslegs and Blay for the tips.