Bully breeds are known to be incredibly sensitive to skin irritations. Was your dog exposed to any plants, cleaners, new food, vaccinations etc? Is there anything new in his environment? Just like people, dogs can get hives. They usually appear and then disappear within 24 hours. Dogs can be given Benadryl (2 mg per lb orally every eight hours), however I highly suggest seeing your vet to discuss this issue.
