One column per dog, one row per fact
The layout that works for three dogs is a grid, not three separate pages. Put the dogs across the top as three columns, each headed by a clear photo, the dog's name in large type, and one identifying line such as color, size, and collar color, because in a multi-dog house the first sitter mistake is always feeding or medicating the wrong dog. Down the side, keep the same rows for every dog in the same order: food, amount and times, medicines, walk routine, vet, allergies or health flags, behavior quirks, and sleeping place.
Identical rows are the whole trick. A sitter reads down one column for the dog in front of her, and a vet reads across one row to compare all three dogs on the same fact. The moment one column grows extra paragraphs the others lack, scanning breaks down.
The facts a sitter reads first
A sitter's first hour runs on feeding, doors, and walks, so those rows must be exact. Write food by name and amount in the measure the sitter will actually use, such as two cups from the blue scoop, and say where each dog eats, because three dogs fed in the wrong places can mean guarding or stealing. Note which dog bolts through open gates, which one must be walked separately, and which one is frightened of thunder, deliveries, or the vacuum, with what actually helps.
Medicines belong high on the sheet, written exactly as the labels read, with the time each is given and what to do if a dose is refused, agreed with your vet beforehand. A sitter should never have to interpret handwriting on a bottle while a dog waits.
The facts a new vet reads first
A new veterinarian scanning the same sheet looks for a different layer: ages or birth dates, weights, vaccination status, microchip numbers, known conditions, past surgeries, and any reaction a dog has had to a medicine or sedation. Keep those rows factual and current. If one dog is the senior with a heart condition and another is the youngster with a sensitive stomach, the sheet should make that contrast obvious at a glance rather than burying it in identical-looking text.
Leave a blank dated line at the bottom of each column for whoever uses the sheet to add what happened: a refused meal, a limp noticed on a walk, a vaccine given at the visit. The sheet then returns to you as a record, not just an instruction card.
Keeping a three-dog sheet from going stale
Review the sheet whenever anything changes for any one dog: a new food, a finished course of medicine, a weight change the vet mentions. The failure mode of household sheets is quiet drift, where the sheet still describes last year's dogs. Date the sheet in the corner, replace it whole rather than scribbling corrections, and keep the previous version behind it so changes stay traceable.
Sharing that current one-page version through a KinsLe Care Pass lets a booked sitter open exactly the routines and key details she needs for the stay, while the sheet stays yours to update the moment one of the three dogs changes.