First, sort out what he actually ate
Finding the baking tin open and the dog looking pleased calls for a quick inventory before any treat talk. Count what is left against what was in the tin if you can, and check the dates he could reach: were they the pitted baking kind, or whole dates with stones inside? A few pitted dates usually mean a sugary stomach upset at worst. Whole dates are a different conversation, because the stone inside each one does not digest, and stones are exactly the size to trouble a small or medium dog's intestines. Knowing roughly how many went down, and in what form, is the information your vet will ask for if you ring.
Dates are not raisins — but they are still sugar
Owners often panic because dates resemble the dried fruits that genuinely are dangerous to dogs. Dates themselves are not in that toxic group, which is reassuring after a raid. What they are is dense: natural sugars and fibre packed into a sticky chew. One date chopped over his dinner is a sweet garnish; a bellyful ferments its way to wind, loose stools and a dog bouncing off the walls at midnight. The stickiness also clings to teeth, one more reason dates belong in the rare-treat drawer rather than the daily rotation for any dog, and especially one watching his weight or managing blood-sugar concerns under vet care.
If you share one on purpose
Choose a pitted date, check it anyway by squeezing it open — stones hide in supposedly pitted fruit often enough — then chop it into small pieces so the sticky mass does not glue itself into one gummy mouthful. Offer the pieces mixed through his normal food or as a training novelty, not as a whole date handed over like a chew. One date for a medium dog, half for a small one, and not every day. If the chopped pieces have come straight from a cold tin, let them lose their chill for a few minutes — a cold, sticky lump is harder for a small dog to manage comfortably. Fresh water down afterwards, and a quick tooth check later is no bad thing for a dog who gets sticky treats.
After the pantry raid
For the next day, watch his stool, his appetite and his energy. Loose stools that settle within a day are the usual price of a sugar raid. Repeated vomiting, straining to pass anything, a tender or swelling belly, drooling or sudden quietness after eating fruit with stones are the signs that move this from wait-and-see to a vet call without delay, because an obstructed gut worsens by the hour. Then fix the pantry: a tin a nose can open will be opened again, so the baking shelf gets a latch, a higher shelf or a door that actually clicks shut.
A raid like this is household information, not just one person's discovery — the next feeder needs to know his stomach is already loaded before adding the usual treats. Logging the incident and the treat pause in KinsLe through Care Teams puts that note where everyone who feeds him will see it, with the day's duties adjusted until he is back to normal.