Food safety
Can dogs eat cheese?
Yes, but be careful
Excellent training currency, but rich and salty. Plenty of dogs don't handle dairy well.
How much
Pea-sized pieces, not a slice
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.