Food safety
Can dogs eat grapes, raisins, sultanas, currants?
No — don't give this
Can cause kidney failure in some dogs, and nobody can predict which dogs or what amount. That includes mince pies, fruit cake and granola.
If your dog has already eaten it
Any amount is a same-day vet call.
Being honest about this
Dogs differ, and amount matters — a crumb of something rich is not the same as half a packet. Treats of any kind should stay under a tenth of what your dog eats in a day. If you're unsure, your vet would far rather take the call.
Based on guidance from: Toxic food guidance for dogs — Animal Poison Line / VPIS
Sources & methodology