As in tinned, or do they eat dry stuff? And I thought they were meant to eat slugs we have lots of those!
When do they hibernate? Is it related to day length or temperature?
		
		
	 
They will eat either, moist is generally the first to go in our garden but they are partial to a bit of Iams too. It's best to try avoiding fish based cat food though some hogs tend to eat this also.
Hogs are insectivores (similar to moles and shrews) so prefer insects, catarpillars and worms, though they are carnivores, so will eat different meats. Regarding slugs etc, hogs are the gardener's friend as they do eat a lot of slugs but, slugs carry a parasite called lungworm (nemetode, I think) which will kill an infected, untreated hog. 
A hog will hibernate when it gets too cold to forage, so it is more related to temp than day length. a hog of less than 600 grams will probably not survive hibernation, so sticking some extra food out now could be a big help to your local population.
Hope this helps,
Mick