Thank you for your enquiry. Eating items from the ground (grazing) is quite a common issue for dogs, especially scent and flushing breeds. You are quite right to be concerned as many of the items your dog may show interest in could be dangerous if swallowed. I am happy to give you some general advice but have to assume that your dog is in good health and has had a check up by the vet before raising this question.
Firstly, we need to try and understand, why your dog is doing this? Is it boredom? If so, then we need to increase outdoor games and interaction with him. If not, then your dog could just like the texture or the taste of the items it is seeking to pick up. If this is the case then we need to lower the ‘reward’ value of these ‘objects’.
We can do this in one of three ways: –
1. Redirection: When your dog shows the first signs of wishing to interact, or pick up, an item then you get your dog’s attention on you, offer it something more appealing (i.e. a high value treat) and, after the treat has been taken, move (guide) away from the area of interest. Apart from instruction your dog to look at you there is no need to issue any further instruction when you are guiding your dog away. Once you are clear enough away from the area get your dog to sit and reward him for doing so then continue your walk maintaining distance from the area.
2. Lower value of the items: Another technique that can be used is to place on the ground something better for your dog that will reduce the ‘value’ of the items, or objects, your dog has shown interest in. You can do this be scatter feeding in the area and other areas. this will teach your dog that their is good stuff to be had in the ground (that you have provided) that will give him satisfaction greater than stones/pebbles on the ground. This game instantly reduces the value of items on the ground in favour of your treats and also creates some mental stimulation via the reward of playing the hunting game.
3. Scent hunting: Similar to scatter feeding you can, if your dog has a natural propensity to comprehensively sniff things, teach your dog scent hunting. This game, if your dog shows signs of engaging with and enjoying this activity, will transform the ground into a ‘treasure’ map to be explored with the discovery item set by you. Again, as with scatter feeding, all other items will have their ‘reward’ value reduced by comparison. There are scent clubs or scent training videos on You Tube, that will get you started in this.
I hope this helps. Let me know how you get on.