Bonnie and Sam

My sister's elderly dogs, both are 14 and she has had them both since they were puppies. Unfortunately Bonnie is feeling her age, my sister doesn't know how long she has left. She can't walk far anymore. Sad to see beloved pets get old. But Bonnie always looks so happy when she sees anyone, so my sister feels that she is still enjoying her life at them moment, but knows as soon as she starts suffering then a hard phone call will have to be made. :(