I have just been away on holiday with my dog and while away ran out of dog food. The person I used my friends dog food which my dog loved but after a couple of days he was sick in the evening and ever since has been sick every couple of nights. He was slightly unsettled being away from home so I presumed this was the cause. Since then I found out that I should have gradually changed the diet which I did not do. If it is the diet that has caused this upset what should I do to solve the problem?

has he had the runs aswell?
normally a change of food causes an upset tummy if its not done gradually. but ive never experienced a dog being sick because of change of food but maybe this new food was just to rich for his tummy

No runs. he had the runs on the previous diet which is one of the reasons why I changed. He has been totally well in himself other than the sickness. Not sure how you tell about the richness of the diet but the food is 'ruff and ready'

I would probably suspect it was the change in food that caused his sickness, particularly if he's well within himself apart from that.  Changing food so swiftly is often a cause of upset, be it out one end, the other and both if you're really lucky! :)  Try giving him some pro-biotic yoghurt to sooth his stomach and make sure he plenty of water-ofcourse if he continues being sick or you are at all concerned about him, you should consult your vet, but give him a few days and he'll more than likely settle back down once his tummy has! :)

HTH :)