I have 3 dogs (1 was 12 when I got her), 2 are Jack Russel x's and one is pure Jack Russell, They are all rescue dogs and non of them take any notice of my piggies. When I got my sugar gliders they were very interested in them but they soon learnt it was a no no and now they take no notice at all. The piggies are a new addition but not one of them has taken any notice. So with training I think any of them can learn. My friend had a lurcher who used to curl up with her rabbit and piggies. Another friend has 2 piggies and their JRT plays with them, he cleans them and the piggies climb on him. All dogs obviously have the potential but as long as they are trained and not left unsupervised any breed should be ok.