I phoned the vet's office and talked to the technician. She mentioned benedryl which is diphenhydramine that is often given to dogs and is an over the counter anti-histamine. I tend to take Fraser to the vet at any sign of anything really, and it's always been nothing in particular. However, he'll probably be at the vets later today as I don't want to be giving him over the counter drugs without knowing exactly what dosage. He was okay all night, no problem breathing and last evening only really started up when I put him outside for his late night pee and he started up immediately he was out the door. This morning when he woke up he started sneezing, but when he went outside, he started up the reverse sneezing. So it does seem related to air temperature or whatever's outside in the air that is stronger than in the house. I'm trying not to be such an anxious parent, but what the hey. He's my precious boy and not worth taking chances.