Royal Canin Jack Russell Terrier Adult is designed exclusively for purebred Jack Russell Terriers over 10 months. The Jack Russell Terrier has a strong and rectangular jaw, and the breed has large teeth that are set square to the jaws. The size, shape and texture of the kibble is designed to be easy for the Jack Russell Terrier to pick up and encourages chewing. Royal Canin provides an exclusive kibble for each breed - a concentration of technical expertise born from the unique knowledge of Royal Canin combined with the practical experience of breeders.