My bouncy Jack Russell terrier gets a bit bored I think and keeps chasing the birds in the garden. He loves to have balls thrown for him but there's a limit to how long we can spend doing that! I feel like buying him some more toys/chews to keep him occupied, but he is very hard chewer. I don't want to break his teeth on things like Nyla bones or antlers, and he has a sensitive digestion so don't want to give him things like pizzles, any recommendations for interesting toys? Thanks.