I had a JRT that was obsessed with any ball,I got her at 6wks old had all the jabs and started taking her out rabbiting/rating,she killed a few rats bolted a few rabbits,but as soon as we got home she went to look for her ball,walked around with it in her mouth all the time,she is now a year old and and living with my mum still chasing balls and sleeping at the foot of my mums bed it would rather do that then hunt,but if you where to hide her ball she would hunt for hrs till she found it
Thats just what she prefers, and that dog was supposedly from working parants just shows you never know w