In dogs , most reactions to insect venom are localized, i.e., swollen eyes, lips and ears (although I've seen some dachshunds where their entire body swelled!) On occasion, the reaction can be life threatening and involve their airway and can be a very frightening experience for the owner and pet. I would suggest (can't prescribe since I'm only licensed in NY) that all my beekeeping friends with dogs have over-the-counter(OTC) benedryl on hand. The dosage for dogs is 1 mg per pound given every 8 hours (write this on the box since human dosages don't apply to dogs) until signs subside, if you don't see a response in a few hours or conditions worsen, please see your veterinarian ASAP! Most OTC benedryl is 25 mg (check the label), so for a 70-ish pound Lab, give three capsules, three times a day. It pays to call your veterinarian to give them a heads up in case you're dog has other medical issues and should be seen. If nothing else, they can update your dogs records for future reference.
You're all right, most dogs are smart enough to avoid the bees after a sting. A few are repeat offenders - like some of us humans they are wooden-headed and never learn!
Hope this is helpful,
Steve