Pet Care Needed

We are looking for about 10 walks in the next number of months due to our dog walker taking vacation and having appointments. Would love to have someone on-hand to be "on-call" if we need someone to let our dog out/walk her (once every month or two) and be a potential overnight sitter at our condo. Tully is a 10-year-old boxer who is used to a walk 3 times a day with each walk averaging 15-20 min. At this point she is lower in her energy level as she's aging. We also have a cat.