I had 2 older rats just over 3 years old. One has passed away. The other is still well and energetic. I do not want to commit to introducing another pair of rats for companionship at this time. It would mean another 3+ year commitment. I am offering him out of the cage time with me every day as well as daily time in the exercise ball. I am worried about the loss of companionship. Is anyone aware of a short term solution for companionship or a suitable surrogate partner?