
Could be his not got the appitite at the moment.
I've had dogs in the past who haven't been hungery where there's been a sudden rise in the tempreture and don't eat for a day or two and started being picky. They soon picked up again when they got hungery. The fact that he ate wet food is because it smells better and seems more appealing to alot of dogs. bit like me and chocolate. I mgiht not be hungery so won't eat the ham sandwhich but give me a chocolate bar. although not hungery, will still eat it! :-D
Is he drinking normally and does he seem himself? I would not give him wet food (He will think if he doesn't eat he will get something better!) and give him a couple of days of his dry food to see if he will eat. also a trip to the vets won't do any harm if he starts looking under the weather, just for a check over :)
I would have thought it's just the weather and I know of some Vizsla's that arn't the best eaters in the world anyway.