A sitter cancelling mid-trip is not a remote possibility to worry about vaguely. Illness, family emergencies, and work crises land without regard for your itinerary, and the difference between a ruined trip and a managed problem is whether the replacement plan already exists on paper, in the hands of a person who agreed to it while calm.
Name the Backup Person, and Get a Real Agreement
Choose the backup for reliability and proximity rather than affection alone: someone local who knows your dog, can reach your home quickly, and can realistically take over feeding, walks, and medicines at short notice. Ask them directly and specifically, describing what taking over would actually involve and for how many days it could last, and treat anything short of a clear yes as a no. Name that person in the written plan, with their phone number at the top, and tell your sitter who they are, because the sitter is usually the one who must make the first call. A backup who learns of their role from a stranger's phone call during a crisis has been given a surprise, not a plan, and surprises get declined. Reconfirm the arrangement a few days before each trip, since willingness in spring may not survive a changed job or a new baby by autumn.
Their Own Copy, Keys, and Access
The backup needs everything the sitter has, held in advance rather than fetched during the handover: their own complete copy of the care instructions, including feeding, medicines with the initialled chart method, vet details, and your contact order; a working key or access arrangement they have actually tested on your door; and any codes, parking details, or alarm instructions the takeover requires. Walk them through the house once if they have not cared for your dog there before, showing where food, medicines, leads, and cleaning supplies live. The moment a cancellation lands is the wrong moment to discover that the spare key opens the porch but not the inner door, or that the instructions mention a cupboard the backup has never seen. Their copy should be identical to the sitter's, so whichever person is on duty, your dog's care reads the same.
The Activation Trigger and the Order of Calls
Write the trigger in plain terms: the plan activates the moment the sitter tells you, or tells the backup directly, that they cannot continue, for any reason, at any point in the trip. Do not leave the backup guessing whether a one-day problem counts or whether they should wait for you to decide from another time zone. Set out the order of calls beside the trigger: the sitter informs you and the backup, the backup confirms they are taking over and from when, and you confirm any cost arrangements. State what the backup may authorise in your absence, such as a vet visit for illness or injury, and how expenses will be settled, so a willing helper is never left weighing your dog's care against their own wallet.
The Boarding Fallback Behind the Backup
One person may not be able to cover every remaining day, so the written plan needs a second layer: a boarding facility that knows your dog, named with its phone number, its booking requirements, and a note of whether it can take him at short notice or holds an existing relationship with you. Record who would transport him there and what paperwork the facility needs, so the fallback is executable rather than aspirational. KinsLe eases that last handover as well, since the Pet Passport travels with your dog as his records packet, meaning the boarding facility gets his vet and vaccination details in full whether he arrives from your sitter, your backup, or you.